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-rw-r--r--block/Kconfig12
-rw-r--r--block/Kconfig.iosched30
-rw-r--r--block/Makefile3
-rw-r--r--block/bfq-cgroup.c1139
-rw-r--r--block/bfq-iosched.c5047
-rw-r--r--block/bfq-iosched.h941
-rw-r--r--block/bfq-wf2q.c1616
-rw-r--r--block/bio.c80
-rw-r--r--block/blk-cgroup.c123
-rw-r--r--block/blk-core.c143
-rw-r--r--block/blk-exec.c11
-rw-r--r--block/blk-flush.c5
-rw-r--r--block/blk-integrity.c24
-rw-r--r--block/blk-lib.c78
-rw-r--r--block/blk-merge.c17
-rw-r--r--block/blk-mq-debugfs.c331
-rw-r--r--block/blk-mq-pci.c2
-rw-r--r--block/blk-mq-sched.c272
-rw-r--r--block/blk-mq-sched.h43
-rw-r--r--block/blk-mq-sysfs.c61
-rw-r--r--block/blk-mq-tag.c5
-rw-r--r--block/blk-mq.c636
-rw-r--r--block/blk-mq.h18
-rw-r--r--block/blk-settings.c3
-rw-r--r--block/blk-stat.c323
-rw-r--r--block/blk-stat.h204
-rw-r--r--block/blk-sysfs.c84
-rw-r--r--block/blk-throttle.c985
-rw-r--r--block/blk-timeout.c1
-rw-r--r--block/blk-wbt.c95
-rw-r--r--block/blk-wbt.h16
-rw-r--r--block/blk.h15
-rw-r--r--block/bsg-lib.c8
-rw-r--r--block/bsg.c14
-rw-r--r--block/cfq-iosched.c17
-rw-r--r--block/compat_ioctl.c2
-rw-r--r--block/elevator.c129
-rw-r--r--block/genhd.c20
-rw-r--r--block/ioctl.c4
-rw-r--r--block/ioprio.c12
-rw-r--r--block/kyber-iosched.c719
-rw-r--r--block/partition-generic.c1
-rw-r--r--block/scsi_ioctl.c23
-rw-r--r--block/sed-opal.c153
-rw-r--r--block/t10-pi.c8
45 files changed, 12119 insertions, 1354 deletions
diff --git a/block/Kconfig b/block/Kconfig
index 93da7fc3f254..a8ad7e77db28 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -116,6 +116,18 @@ config BLK_DEV_THROTTLING
See Documentation/cgroups/blkio-controller.txt for more information.
+config BLK_DEV_THROTTLING_LOW
+ bool "Block throttling .low limit interface support (EXPERIMENTAL)"
+ depends on BLK_DEV_THROTTLING
+ default n
+ ---help---
+ Add .low limit interface for block throttling. The low limit is a best
+ effort limit to prioritize cgroups. Depending on the setting, the limit
+ can be used to protect cgroups in terms of bandwidth/iops and better
+ utilize disk resource.
+
+ Note, this is an experimental interface and could be changed someday.
+
config BLK_CMDLINE_PARSER
bool "Block device command line partition parser"
default n
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index 58fc8684788d..fd2cefa47d35 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -40,6 +40,7 @@ config CFQ_GROUP_IOSCHED
Enable group IO scheduling in CFQ.
choice
+
prompt "Default I/O scheduler"
default DEFAULT_CFQ
help
@@ -69,6 +70,35 @@ config MQ_IOSCHED_DEADLINE
---help---
MQ version of the deadline IO scheduler.
+config MQ_IOSCHED_KYBER
+ tristate "Kyber I/O scheduler"
+ default y
+ ---help---
+ The Kyber I/O scheduler is a low-overhead scheduler suitable for
+ multiqueue and other fast devices. Given target latencies for reads and
+ synchronous writes, it will self-tune queue depths to achieve that
+ goal.
+
+config IOSCHED_BFQ
+ tristate "BFQ I/O scheduler"
+ default n
+ ---help---
+ BFQ I/O scheduler for BLK-MQ. BFQ distributes the bandwidth of
+ of the device among all processes according to their weights,
+ regardless of the device parameters and with any workload. It
+ also guarantees a low latency to interactive and soft
+ real-time applications. Details in
+ Documentation/block/bfq-iosched.txt
+
+config BFQ_GROUP_IOSCHED
+ bool "BFQ hierarchical scheduling support"
+ depends on IOSCHED_BFQ && BLK_CGROUP
+ default n
+ ---help---
+
+ Enable hierarchical scheduling in BFQ, using the blkio
+ (cgroups-v1) or io (cgroups-v2) controller.
+
endmenu
endif
diff --git a/block/Makefile b/block/Makefile
index 081bb680789b..2b281cf258a0 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -20,6 +20,9 @@ obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o
+obj-$(CONFIG_MQ_IOSCHED_KYBER) += kyber-iosched.o
+bfq-y := bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
+obj-$(CONFIG_IOSCHED_BFQ) += bfq.o
obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o
obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
new file mode 100644
index 000000000000..c8a32fb345cf
--- /dev/null
+++ b/block/bfq-cgroup.c
@@ -0,0 +1,1139 @@
+/*
+ * cgroups support for the BFQ I/O scheduler.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/cgroup.h>
+#include <linux/elevator.h>
+#include <linux/ktime.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include <linux/sbitmap.h>
+#include <linux/delay.h>
+
+#include "bfq-iosched.h"
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+
+/* bfqg stats flags */
+enum bfqg_stats_flags {
+ BFQG_stats_waiting = 0,
+ BFQG_stats_idling,
+ BFQG_stats_empty,
+};
+
+#define BFQG_FLAG_FNS(name) \
+static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \
+{ \
+ stats->flags |= (1 << BFQG_stats_##name); \
+} \
+static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \
+{ \
+ stats->flags &= ~(1 << BFQG_stats_##name); \
+} \
+static int bfqg_stats_##name(struct bfqg_stats *stats) \
+{ \
+ return (stats->flags & (1 << BFQG_stats_##name)) != 0; \
+} \
+
+BFQG_FLAG_FNS(waiting)
+BFQG_FLAG_FNS(idling)
+BFQG_FLAG_FNS(empty)
+#undef BFQG_FLAG_FNS
+
+/* This should be called with the queue_lock held. */
+static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
+{
+ unsigned long long now;
+
+ if (!bfqg_stats_waiting(stats))
+ return;
+
+ now = sched_clock();
+ if (time_after64(now, stats->start_group_wait_time))
+ blkg_stat_add(&stats->group_wait_time,
+ now - stats->start_group_wait_time);
+ bfqg_stats_clear_waiting(stats);
+}
+
+/* This should be called with the queue_lock held. */
+static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
+ struct bfq_group *curr_bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ if (bfqg_stats_waiting(stats))
+ return;
+ if (bfqg == curr_bfqg)
+ return;
+ stats->start_group_wait_time = sched_clock();
+ bfqg_stats_mark_waiting(stats);
+}
+
+/* This should be called with the queue_lock held. */
+static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
+{
+ unsigned long long now;
+
+ if (!bfqg_stats_empty(stats))
+ return;
+
+ now = sched_clock();
+ if (time_after64(now, stats->start_empty_time))
+ blkg_stat_add(&stats->empty_time,
+ now - stats->start_empty_time);
+ bfqg_stats_clear_empty(stats);
+}
+
+void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
+{
+ blkg_stat_add(&bfqg->stats.dequeue, 1);
+}
+
+void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ if (blkg_rwstat_total(&stats->queued))
+ return;
+
+ /*
+ * group is already marked empty. This can happen if bfqq got new
+ * request in parent group and moved to this group while being added
+ * to service tree. Just ignore the event and move on.
+ */
+ if (bfqg_stats_empty(stats))
+ return;
+
+ stats->start_empty_time = sched_clock();
+ bfqg_stats_mark_empty(stats);
+}
+
+void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ if (bfqg_stats_idling(stats)) {
+ unsigned long long now = sched_clock();
+
+ if (time_after64(now, stats->start_idle_time))
+ blkg_stat_add(&stats->idle_time,
+ now - stats->start_idle_time);
+ bfqg_stats_clear_idling(stats);
+ }
+}
+
+void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ stats->start_idle_time = sched_clock();
+ bfqg_stats_mark_idling(stats);
+}
+
+void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+
+ blkg_stat_add(&stats->avg_queue_size_sum,
+ blkg_rwstat_total(&stats->queued));
+ blkg_stat_add(&stats->avg_queue_size_samples, 1);
+ bfqg_stats_update_group_wait_time(stats);
+}
+
+/*
+ * blk-cgroup policy-related handlers
+ * The following functions help in converting between blk-cgroup
+ * internal structures and BFQ-specific structures.
+ */
+
+static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
+{
+ return pd ? container_of(pd, struct bfq_group, pd) : NULL;
+}
+
+struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
+{
+ return pd_to_blkg(&bfqg->pd);
+}
+
+static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
+{
+ return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq));
+}
+
+/*
+ * bfq_group handlers
+ * The following functions help in navigating the bfq_group hierarchy
+ * by allowing to find the parent of a bfq_group or the bfq_group
+ * associated to a bfq_queue.
+ */
+
+static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
+{
+ struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
+
+ return pblkg ? blkg_to_bfqg(pblkg) : NULL;
+}
+
+struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *group_entity = bfqq->entity.parent;
+
+ return group_entity ? container_of(group_entity, struct bfq_group,
+ entity) :
+ bfqq->bfqd->root_group;
+}
+
+/*
+ * The following two functions handle get and put of a bfq_group by
+ * wrapping the related blk-cgroup hooks.
+ */
+
+static void bfqg_get(struct bfq_group *bfqg)
+{
+ return blkg_get(bfqg_to_blkg(bfqg));
+}
+
+void bfqg_put(struct bfq_group *bfqg)
+{
+ return blkg_put(bfqg_to_blkg(bfqg));
+}
+
+void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
+ unsigned int op)
+{
+ blkg_rwstat_add(&bfqg->stats.queued, op, 1);
+ bfqg_stats_end_empty_time(&bfqg->stats);
+ if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
+ bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
+}
+
+void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
+{
+ blkg_rwstat_add(&bfqg->stats.queued, op, -1);
+}
+
+void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
+{
+ blkg_rwstat_add(&bfqg->stats.merged, op, 1);
+}
+
+void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
+ uint64_t io_start_time, unsigned int op)
+{
+ struct bfqg_stats *stats = &bfqg->stats;
+ unsigned long long now = sched_clock();
+
+ if (time_after64(now, io_start_time))
+ blkg_rwstat_add(&stats->service_time, op,
+ now - io_start_time);
+ if (time_after64(io_start_time, start_time))
+ blkg_rwstat_add(&stats->wait_time, op,
+ io_start_time - start_time);
+}
+
+/* @stats = 0 */
+static void bfqg_stats_reset(struct bfqg_stats *stats)
+{
+ /* queued stats shouldn't be cleared */
+ blkg_rwstat_reset(&stats->merged);
+ blkg_rwstat_reset(&stats->service_time);
+ blkg_rwstat_reset(&stats->wait_time);
+ blkg_stat_reset(&stats->time);
+ blkg_stat_reset(&stats->avg_queue_size_sum);
+ blkg_stat_reset(&stats->avg_queue_size_samples);
+ blkg_stat_reset(&stats->dequeue);
+ blkg_stat_reset(&stats->group_wait_time);
+ blkg_stat_reset(&stats->idle_time);
+ blkg_stat_reset(&stats->empty_time);
+}
+
+/* @to += @from */
+static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
+{
+ if (!to || !from)
+ return;
+
+ /* queued stats shouldn't be cleared */
+ blkg_rwstat_add_aux(&to->merged, &from->merged);
+ blkg_rwstat_add_aux(&to->service_time, &from->service_time);
+ blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
+ blkg_stat_add_aux(&from->time, &from->time);
+ blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
+ blkg_stat_add_aux(&to->avg_queue_size_samples,
+ &from->avg_queue_size_samples);
+ blkg_stat_add_aux(&to->dequeue, &from->dequeue);
+ blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
+ blkg_stat_add_aux(&to->idle_time, &from->idle_time);
+ blkg_stat_add_aux(&to->empty_time, &from->empty_time);
+}
+
+/*
+ * Transfer @bfqg's stats to its parent's aux counts so that the ancestors'
+ * recursive stats can still account for the amount used by this bfqg after
+ * it's gone.
+ */
+static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
+{
+ struct bfq_group *parent;
+
+ if (!bfqg) /* root_group */
+ return;
+
+ parent = bfqg_parent(bfqg);
+
+ lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock);
+
+ if (unlikely(!parent))
+ return;
+
+ bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
+ bfqg_stats_reset(&bfqg->stats);
+}
+
+void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ if (bfqq) {
+ bfqq->ioprio = bfqq->new_ioprio;
+ bfqq->ioprio_class = bfqq->new_ioprio_class;
+ bfqg_get(bfqg);
+ }
+ entity->parent = bfqg->my_entity; /* NULL for root group */
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static void bfqg_stats_exit(struct bfqg_stats *stats)
+{
+ blkg_rwstat_exit(&stats->merged);
+ blkg_rwstat_exit(&stats->service_time);
+ blkg_rwstat_exit(&stats->wait_time);
+ blkg_rwstat_exit(&stats->queued);
+ blkg_stat_exit(&stats->time);
+ blkg_stat_exit(&stats->avg_queue_size_sum);
+ blkg_stat_exit(&stats->avg_queue_size_samples);
+ blkg_stat_exit(&stats->dequeue);
+ blkg_stat_exit(&stats->group_wait_time);
+ blkg_stat_exit(&stats->idle_time);
+ blkg_stat_exit(&stats->empty_time);
+}
+
+static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
+{
+ if (blkg_rwstat_init(&stats->merged, gfp) ||
+ blkg_rwstat_init(&stats->service_time, gfp) ||
+ blkg_rwstat_init(&stats->wait_time, gfp) ||
+ blkg_rwstat_init(&stats->queued, gfp) ||
+ blkg_stat_init(&stats->time, gfp) ||
+ blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
+ blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
+ blkg_stat_init(&stats->dequeue, gfp) ||
+ blkg_stat_init(&stats->group_wait_time, gfp) ||
+ blkg_stat_init(&stats->idle_time, gfp) ||
+ blkg_stat_init(&stats->empty_time, gfp)) {
+ bfqg_stats_exit(stats);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
+{
+ return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
+}
+
+static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
+{
+ return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
+}
+
+struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
+{
+ struct bfq_group_data *bgd;
+
+ bgd = kzalloc(sizeof(*bgd), gfp);
+ if (!bgd)
+ return NULL;
+ return &bgd->pd;
+}
+
+void bfq_cpd_init(struct blkcg_policy_data *cpd)
+{
+ struct bfq_group_data *d = cpd_to_bfqgd(cpd);
+
+ d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
+ CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
+}
+
+void bfq_cpd_free(struct blkcg_policy_data *cpd)
+{
+ kfree(cpd_to_bfqgd(cpd));
+}
+
+struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
+{
+ struct bfq_group *bfqg;
+
+ bfqg = kzalloc_node(sizeof(*bfqg), gfp, node);
+ if (!bfqg)
+ return NULL;
+
+ if (bfqg_stats_init(&bfqg->stats, gfp)) {
+ kfree(bfqg);
+ return NULL;
+ }
+
+ return &bfqg->pd;
+}
+
+void bfq_pd_init(struct blkg_policy_data *pd)
+{
+ struct blkcg_gq *blkg = pd_to_blkg(pd);
+ struct bfq_group *bfqg = blkg_to_bfqg(blkg);
+ struct bfq_data *bfqd = blkg->q->elevator->elevator_data;
+ struct bfq_entity *entity = &bfqg->entity;
+ struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg);
+
+ entity->orig_weight = entity->weight = entity->new_weight = d->weight;
+ entity->my_sched_data = &bfqg->sched_data;
+ bfqg->my_entity = entity; /*
+ * the root_group's will be set to NULL
+ * in bfq_init_queue()
+ */
+ bfqg->bfqd = bfqd;
+ bfqg->active_entities = 0;
+ bfqg->rq_pos_tree = RB_ROOT;
+}
+
+void bfq_pd_free(struct blkg_policy_data *pd)
+{
+ struct bfq_group *bfqg = pd_to_bfqg(pd);
+
+ bfqg_stats_exit(&bfqg->stats);
+ return kfree(bfqg);
+}
+
+void bfq_pd_reset_stats(struct blkg_policy_data *pd)
+{
+ struct bfq_group *bfqg = pd_to_bfqg(pd);
+
+ bfqg_stats_reset(&bfqg->stats);
+}
+
+static void bfq_group_set_parent(struct bfq_group *bfqg,
+ struct bfq_group *parent)
+{
+ struct bfq_entity *entity;
+
+ entity = &bfqg->entity;
+ entity->parent = parent->my_entity;
+ entity->sched_data = &parent->sched_data;
+}
+
+static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd,
+ struct blkcg *blkcg)
+{
+ struct blkcg_gq *blkg;
+
+ blkg = blkg_lookup(blkcg, bfqd->queue);
+ if (likely(blkg))
+ return blkg_to_bfqg(blkg);
+ return NULL;
+}
+
+struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
+ struct blkcg *blkcg)
+{
+ struct bfq_group *bfqg, *parent;
+ struct bfq_entity *entity;
+
+ bfqg = bfq_lookup_bfqg(bfqd, blkcg);
+
+ if (unlikely(!bfqg))
+ return NULL;
+
+ /*
+ * Update chain of bfq_groups as we might be handling a leaf group
+ * which, along with some of its relatives, has not been hooked yet
+ * to the private hierarchy of BFQ.
+ */
+ entity = &bfqg->entity;
+ for_each_entity(entity) {
+ bfqg = container_of(entity, struct bfq_group, entity);
+ if (bfqg != bfqd->root_group) {
+ parent = bfqg_parent(bfqg);
+ if (!parent)
+ parent = bfqd->root_group;
+ bfq_group_set_parent(bfqg, parent);
+ }
+ }
+
+ return bfqg;
+}
+
+/**
+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
+ * @bfqd: queue descriptor.
+ * @bfqq: the queue to move.
+ * @bfqg: the group to move to.
+ *
+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
+ * it on the new one. Avoid putting the entity on the old group idle tree.
+ *
+ * Must be called under the queue lock; the cgroup owning @bfqg must
+ * not disappear (by now this just means that we are called under
+ * rcu_read_lock()).
+ */
+void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_group *bfqg)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ /* If bfqq is empty, then bfq_bfqq_expire also invokes
+ * bfq_del_bfqq_busy, thereby removing bfqq and its entity
+ * from data structures related to current group. Otherwise we
+ * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
+ * we do below.
+ */
+ if (bfqq == bfqd->in_service_queue)
+ bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
+ false, BFQQE_PREEMPTED);
+
+ if (bfq_bfqq_busy(bfqq))
+ bfq_deactivate_bfqq(bfqd, bfqq, false, false);
+ else if (entity->on_st)
+ bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
+ bfqg_put(bfqq_group(bfqq));
+
+ /*
+ * Here we use a reference to bfqg. We don't need a refcounter
+ * as the cgroup reference will not be dropped, so that its
+ * destroy() callback will not be invoked.
+ */
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+ bfqg_get(bfqg);
+
+ if (bfq_bfqq_busy(bfqq)) {
+ bfq_pos_tree_add_move(bfqd, bfqq);
+ bfq_activate_bfqq(bfqd, bfqq);
+ }
+
+ if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+}
+
+/**
+ * __bfq_bic_change_cgroup - move @bic to @cgroup.
+ * @bfqd: the queue descriptor.
+ * @bic: the bic to move.
+ * @blkcg: the blk-cgroup to move to.
+ *
+ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller
+ * has to make sure that the reference to cgroup is valid across the call.
+ *
+ * NOTE: an alternative approach might have been to store the current
+ * cgroup in bfqq and getting a reference to it, reducing the lookup
+ * time here, at the price of slightly more complex code.
+ */
+static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
+ struct bfq_io_cq *bic,
+ struct blkcg *blkcg)
+{
+ struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
+ struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
+ struct bfq_group *bfqg;
+ struct bfq_entity *entity;
+
+ bfqg = bfq_find_set_group(bfqd, blkcg);
+
+ if (unlikely(!bfqg))
+ bfqg = bfqd->root_group;
+
+ if (async_bfqq) {
+ entity = &async_bfqq->entity;
+
+ if (entity->sched_data != &bfqg->sched_data) {
+ bic_set_bfqq(bic, NULL, 0);
+ bfq_log_bfqq(bfqd, async_bfqq,
+ "bic_change_group: %p %d",
+ async_bfqq, async_bfqq->ref);
+ bfq_put_queue(async_bfqq);
+ }
+ }
+
+ if (sync_bfqq) {
+ entity = &sync_bfqq->entity;
+ if (entity->sched_data != &bfqg->sched_data)
+ bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
+ }
+
+ return bfqg;
+}
+
+void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
+{
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+ struct bfq_group *bfqg = NULL;
+ uint64_t serial_nr;
+
+ rcu_read_lock();
+ serial_nr = bio_blkcg(bio)->css.serial_nr;
+
+ /*
+ * Check whether blkcg has changed. The condition may trigger
+ * spuriously on a newly created cic but there's no harm.
+ */
+ if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
+ goto out;
+
+ bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
+ bic->blkcg_serial_nr = serial_nr;
+out:
+ rcu_read_unlock();
+}
+
+/**
+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
+ * @st: the service tree being flushed.
+ */
+static void bfq_flush_idle_tree(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entity = st->first_idle;
+
+ for (; entity ; entity = st->first_idle)
+ __bfq_deactivate_entity(entity, false);
+}
+
+/**
+ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
+ * @bfqd: the device data structure with the root group.
+ * @entity: the entity to move.
+ */
+static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
+}
+
+/**
+ * bfq_reparent_active_entities - move to the root group all active
+ * entities.
+ * @bfqd: the device data structure with the root group.
+ * @bfqg: the group to move from.
+ * @st: the service tree with the entities.
+ *
+ * Needs queue_lock to be taken and reference to be valid over the call.
+ */
+static void bfq_reparent_active_entities(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ struct bfq_service_tree *st)
+{
+ struct rb_root *active = &st->active;
+ struct bfq_entity *entity = NULL;
+
+ if (!RB_EMPTY_ROOT(&st->active))
+ entity = bfq_entity_of(rb_first(active));
+
+ for (; entity ; entity = bfq_entity_of(rb_first(active)))
+ bfq_reparent_leaf_entity(bfqd, entity);
+
+ if (bfqg->sched_data.in_service_entity)
+ bfq_reparent_leaf_entity(bfqd,
+ bfqg->sched_data.in_service_entity);
+}
+
+/**
+ * bfq_pd_offline - deactivate the entity associated with @pd,
+ * and reparent its children entities.
+ * @pd: descriptor of the policy going offline.
+ *
+ * blkio already grabs the queue_lock for us, so no need to use
+ * RCU-based magic
+ */
+void bfq_pd_offline(struct blkg_policy_data *pd)
+{
+ struct bfq_service_tree *st;
+ struct bfq_group *bfqg = pd_to_bfqg(pd);
+ struct bfq_data *bfqd = bfqg->bfqd;
+ struct bfq_entity *entity = bfqg->my_entity;
+ unsigned long flags;
+ int i;
+
+ if (!entity) /* root group */
+ return;
+
+ spin_lock_irqsave(&bfqd->lock, flags);
+ /*
+ * Empty all service_trees belonging to this group before
+ * deactivating the group itself.
+ */
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
+ st = bfqg->sched_data.service_tree + i;
+
+ /*
+ * The idle tree may still contain bfq_queues belonging
+ * to exited task because they never migrated to a different
+ * cgroup from the one being destroyed now. No one else
+ * can access them so it's safe to act without any lock.
+ */
+ bfq_flush_idle_tree(st);
+
+ /*
+ * It may happen that some queues are still active
+ * (busy) upon group destruction (if the corresponding
+ * processes have been forced to terminate). We move
+ * all the leaf entities corresponding to these queues
+ * to the root_group.
+ * Also, it may happen that the group has an entity
+ * in service, which is disconnected from the active
+ * tree: it must be moved, too.
+ * There is no need to put the sync queues, as the
+ * scheduler has taken no reference.
+ */
+ bfq_reparent_active_entities(bfqd, bfqg, st);
+ }
+
+ __bfq_deactivate_entity(entity, false);
+ bfq_put_async_queues(bfqd, bfqg);
+
+ spin_unlock_irqrestore(&bfqd->lock, flags);
+ /*
+ * @blkg is going offline and will be ignored by
+ * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
+ * that they don't get lost. If IOs complete after this point, the
+ * stats for them will be lost. Oh well...
+ */
+ bfqg_stats_xfer_dead(bfqg);
+}
+
+void bfq_end_wr_async(struct bfq_data *bfqd)
+{
+ struct blkcg_gq *blkg;
+
+ list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
+ struct bfq_group *bfqg = blkg_to_bfqg(blkg);
+
+ bfq_end_wr_async_queues(bfqd, bfqg);
+ }
+ bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+}
+
+static int bfq_io_show_weight(struct seq_file *sf, void *v)
+{
+ struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
+ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
+ unsigned int val = 0;
+
+ if (bfqgd)
+ val = bfqgd->weight;
+
+ seq_printf(sf, "%u\n", val);
+
+ return 0;
+}
+
+static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
+ struct cftype *cftype,
+ u64 val)
+{
+ struct blkcg *blkcg = css_to_blkcg(css);
+ struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
+ struct blkcg_gq *blkg;
+ int ret = -ERANGE;
+
+ if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
+ return ret;
+
+ ret = 0;
+ spin_lock_irq(&blkcg->lock);
+ bfqgd->weight = (unsigned short)val;
+ hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
+ struct bfq_group *bfqg = blkg_to_bfqg(blkg);
+
+ if (!bfqg)
+ continue;
+ /*
+ * Setting the prio_changed flag of the entity
+ * to 1 with new_weight == weight would re-set
+ * the value of the weight to its ioprio mapping.
+ * Set the flag only if necessary.
+ */
+ if ((unsigned short)val != bfqg->entity.new_weight) {
+ bfqg->entity.new_weight = (unsigned short)val;
+ /*
+ * Make sure that the above new value has been
+ * stored in bfqg->entity.new_weight before
+ * setting the prio_changed flag. In fact,
+ * this flag may be read asynchronously (in
+ * critical sections protected by a different
+ * lock than that held here), and finding this
+ * flag set may cause the execution of the code
+ * for updating parameters whose value may
+ * depend also on bfqg->entity.new_weight (in
+ * __bfq_entity_update_weight_prio).
+ * This barrier makes sure that the new value
+ * of bfqg->entity.new_weight is correctly
+ * seen in that code.
+ */
+ smp_wmb();
+ bfqg->entity.prio_changed = 1;
+ }
+ }
+ spin_unlock_irq(&blkcg->lock);
+
+ return ret;
+}
+
+static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ u64 weight;
+ /* First unsigned long found in the file is used */
+ int ret = kstrtoull(strim(buf), 0, &weight);
+
+ if (ret)
+ return ret;
+
+ return bfq_io_set_weight_legacy(of_css(of), NULL, weight);
+}
+
+static int bfqg_print_stat(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
+ &blkcg_policy_bfq, seq_cft(sf)->private, false);
+ return 0;
+}
+
+static int bfqg_print_rwstat(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
+ &blkcg_policy_bfq, seq_cft(sf)->private, true);
+ return 0;
+}
+
+static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
+ &blkcg_policy_bfq, off);
+ return __blkg_prfill_u64(sf, pd, sum);
+}
+
+static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
+ &blkcg_policy_bfq,
+ off);
+ return __blkg_prfill_rwstat(sf, pd, &sum);
+}
+
+static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
+ seq_cft(sf)->private, false);
+ return 0;
+}
+
+static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
+ seq_cft(sf)->private, true);
+ return 0;
+}
+
+static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
+ int off)
+{
+ u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
+
+ return __blkg_prfill_u64(sf, pd, sum >> 9);
+}
+
+static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
+ return 0;
+}
+
+static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
+ offsetof(struct blkcg_gq, stat_bytes));
+ u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
+ atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
+
+ return __blkg_prfill_u64(sf, pd, sum >> 9);
+}
+
+static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
+ false);
+ return 0;
+}
+
+static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
+ struct blkg_policy_data *pd, int off)
+{
+ struct bfq_group *bfqg = pd_to_bfqg(pd);
+ u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
+ u64 v = 0;
+
+ if (samples) {
+ v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
+ v = div64_u64(v, samples);
+ }
+ __blkg_prfill_u64(sf, pd, v);
+ return 0;
+}
+
+/* print avg_queue_size */
+static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
+{
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
+ bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
+ 0, false);
+ return 0;
+}
+
+struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
+{
+ int ret;
+
+ ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
+ if (ret)
+ return NULL;
+
+ return blkg_to_bfqg(bfqd->queue->root_blkg);
+}
+
+struct blkcg_policy blkcg_policy_bfq = {
+ .dfl_cftypes = bfq_blkg_files,
+ .legacy_cftypes = bfq_blkcg_legacy_files,
+
+ .cpd_alloc_fn = bfq_cpd_alloc,
+ .cpd_init_fn = bfq_cpd_init,
+ .cpd_bind_fn = bfq_cpd_init,
+ .cpd_free_fn = bfq_cpd_free,
+
+ .pd_alloc_fn = bfq_pd_alloc,
+ .pd_init_fn = bfq_pd_init,
+ .pd_offline_fn = bfq_pd_offline,
+ .pd_free_fn = bfq_pd_free,
+ .pd_reset_stats_fn = bfq_pd_reset_stats,
+};
+
+struct cftype bfq_blkcg_legacy_files[] = {
+ {
+ .name = "bfq.weight",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = bfq_io_show_weight,
+ .write_u64 = bfq_io_set_weight_legacy,
+ },
+
+ /* statistics, covers only the tasks in the bfqg */
+ {
+ .name = "bfq.time",
+ .private = offsetof(struct bfq_group, stats.time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.sectors",
+ .seq_show = bfqg_print_stat_sectors,
+ },
+ {
+ .name = "bfq.io_service_bytes",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_bytes,
+ },
+ {
+ .name = "bfq.io_serviced",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_ios,
+ },
+ {
+ .name = "bfq.io_service_time",
+ .private = offsetof(struct bfq_group, stats.service_time),
+ .seq_show = bfqg_print_rwstat,
+ },
+ {
+ .name = "bfq.io_wait_time",
+ .private = offsetof(struct bfq_group, stats.wait_time),
+ .seq_show = bfqg_print_rwstat,
+ },
+ {
+ .name = "bfq.io_merged",
+ .private = offsetof(struct bfq_group, stats.merged),
+ .seq_show = bfqg_print_rwstat,
+ },
+ {
+ .name = "bfq.io_queued",
+ .private = offsetof(struct bfq_group, stats.queued),
+ .seq_show = bfqg_print_rwstat,
+ },
+
+ /* the same statictics which cover the bfqg and its descendants */
+ {
+ .name = "bfq.time_recursive",
+ .private = offsetof(struct bfq_group, stats.time),
+ .seq_show = bfqg_print_stat_recursive,
+ },
+ {
+ .name = "bfq.sectors_recursive",
+ .seq_show = bfqg_print_stat_sectors_recursive,
+ },
+ {
+ .name = "bfq.io_service_bytes_recursive",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_bytes_recursive,
+ },
+ {
+ .name = "bfq.io_serviced_recursive",
+ .private = (unsigned long)&blkcg_policy_bfq,
+ .seq_show = blkg_print_stat_ios_recursive,
+ },
+ {
+ .name = "bfq.io_service_time_recursive",
+ .private = offsetof(struct bfq_group, stats.service_time),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.io_wait_time_recursive",
+ .private = offsetof(struct bfq_group, stats.wait_time),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.io_merged_recursive",
+ .private = offsetof(struct bfq_group, stats.merged),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.io_queued_recursive",
+ .private = offsetof(struct bfq_group, stats.queued),
+ .seq_show = bfqg_print_rwstat_recursive,
+ },
+ {
+ .name = "bfq.avg_queue_size",
+ .seq_show = bfqg_print_avg_queue_size,
+ },
+ {
+ .name = "bfq.group_wait_time",
+ .private = offsetof(struct bfq_group, stats.group_wait_time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.idle_time",
+ .private = offsetof(struct bfq_group, stats.idle_time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.empty_time",
+ .private = offsetof(struct bfq_group, stats.empty_time),
+ .seq_show = bfqg_print_stat,
+ },
+ {
+ .name = "bfq.dequeue",
+ .private = offsetof(struct bfq_group, stats.dequeue),
+ .seq_show = bfqg_print_stat,
+ },
+ { } /* terminate */
+};
+
+struct cftype bfq_blkg_files[] = {
+ {
+ .name = "bfq.weight",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = bfq_io_show_weight,
+ .write = bfq_io_set_weight,
+ },
+ {} /* terminate */
+};
+
+#else /* CONFIG_BFQ_GROUP_IOSCHED */
+
+void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
+ unsigned int op) { }
+void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
+void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
+void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
+ uint64_t io_start_time, unsigned int op) { }
+void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
+void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
+void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
+void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
+void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
+
+void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_group *bfqg) {}
+
+void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ if (bfqq) {
+ bfqq->ioprio = bfqq->new_ioprio;
+ bfqq->ioprio_class = bfqq->new_ioprio_class;
+ }
+ entity->sched_data = &bfqg->sched_data;
+}
+
+void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
+
+void bfq_end_wr_async(struct bfq_data *bfqd)
+{
+ bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+}
+
+struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg *blkcg)
+{
+ return bfqd->root_group;
+}
+
+struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
+{
+ return bfqq->bfqd->root_group;
+}
+
+struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ int i;
+
+ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
+ if (!bfqg)
+ return NULL;
+
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ return bfqg;
+}
+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
new file mode 100644
index 000000000000..bd8499ef157c
--- /dev/null
+++ b/block/bfq-iosched.c
@@ -0,0 +1,5047 @@
+/*
+ * Budget Fair Queueing (BFQ) I/O scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ * Arianna Avanzini <avanzini@google.com>
+ *
+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * BFQ is a proportional-share I/O scheduler, with some extra
+ * low-latency capabilities. BFQ also supports full hierarchical
+ * scheduling through cgroups. Next paragraphs provide an introduction
+ * on BFQ inner workings. Details on BFQ benefits, usage and
+ * limitations can be found in Documentation/block/bfq-iosched.txt.
+ *
+ * BFQ is a proportional-share storage-I/O scheduling algorithm based
+ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
+ * budgets, measured in number of sectors, to processes instead of
+ * time slices. The device is not granted to the in-service process
+ * for a given time slice, but until it has exhausted its assigned
+ * budget. This change from the time to the service domain enables BFQ
+ * to distribute the device throughput among processes as desired,
+ * without any distortion due to throughput fluctuations, or to device
+ * internal queueing. BFQ uses an ad hoc internal scheduler, called
+ * B-WF2Q+, to schedule processes according to their budgets. More
+ * precisely, BFQ schedules queues associated with processes. Each
+ * process/queue is assigned a user-configurable weight, and B-WF2Q+
+ * guarantees that each queue receives a fraction of the throughput
+ * proportional to its weight. Thanks to the accurate policy of
+ * B-WF2Q+, BFQ can afford to assign high budgets to I/O-bound
+ * processes issuing sequential requests (to boost the throughput),
+ * and yet guarantee a low latency to interactive and soft real-time
+ * applications.
+ *
+ * In particular, to provide these low-latency guarantees, BFQ
+ * explicitly privileges the I/O of two classes of time-sensitive
+ * applications: interactive and soft real-time. This feature enables
+ * BFQ to provide applications in these classes with a very low
+ * latency. Finally, BFQ also features additional heuristics for
+ * preserving both a low latency and a high throughput on NCQ-capable,
+ * rotational or flash-based devices, and to get the job done quickly
+ * for applications consisting in many I/O-bound processes.
+ *
+ * BFQ is described in [1], where also a reference to the initial, more
+ * theoretical paper on BFQ can be found. The interested reader can find
+ * in the latter paper full details on the main algorithm, as well as
+ * formulas of the guarantees and formal proofs of all the properties.
+ * With respect to the version of BFQ presented in these papers, this
+ * implementation adds a few more heuristics, such as the one that
+ * guarantees a low latency to soft real-time applications, and a
+ * hierarchical extension based on H-WF2Q+.
+ *
+ * B-WF2Q+ is based on WF2Q+, which is described in [2], together with
+ * H-WF2Q+, while the augmented tree used here to implement B-WF2Q+
+ * with O(log N) complexity derives from the one introduced with EEVDF
+ * in [3].
+ *
+ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
+ * Scheduler", Proceedings of the First Workshop on Mobile System
+ * Technologies (MST-2015), May 2015.
+ * http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
+ *
+ * [2] Jon C.R. Bennett and H. Zhang, "Hierarchical Packet Fair Queueing
+ * Algorithms", IEEE/ACM Transactions on Networking, 5(5):675-689,
+ * Oct 1997.
+ *
+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
+ *
+ * [3] I. Stoica and H. Abdel-Wahab, "Earliest Eligible Virtual Deadline
+ * First: A Flexible and Accurate Mechanism for Proportional Share
+ * Resource Allocation", technical report.
+ *
+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/cgroup.h>
+#include <linux/elevator.h>
+#include <linux/ktime.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include <linux/sbitmap.h>
+#include <linux/delay.h>
+
+#include "blk.h"
+#include "blk-mq.h"
+#include "blk-mq-tag.h"
+#include "blk-mq-sched.h"
+#include "bfq-iosched.h"
+
+#define BFQ_BFQQ_FNS(name) \
+void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ __set_bit(BFQQF_##name, &(bfqq)->flags); \
+} \
+void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ __clear_bit(BFQQF_##name, &(bfqq)->flags); \
+} \
+int bfq_bfqq_##name(const struct bfq_queue *bfqq) \
+{ \
+ return test_bit(BFQQF_##name, &(bfqq)->flags); \
+}
+
+BFQ_BFQQ_FNS(just_created);
+BFQ_BFQQ_FNS(busy);
+BFQ_BFQQ_FNS(wait_request);
+BFQ_BFQQ_FNS(non_blocking_wait_rq);
+BFQ_BFQQ_FNS(fifo_expire);
+BFQ_BFQQ_FNS(idle_window);
+BFQ_BFQQ_FNS(sync);
+BFQ_BFQQ_FNS(IO_bound);
+BFQ_BFQQ_FNS(in_large_burst);
+BFQ_BFQQ_FNS(coop);
+BFQ_BFQQ_FNS(split_coop);
+BFQ_BFQQ_FNS(softrt_update);
+#undef BFQ_BFQQ_FNS \
+
+/* Expiration time of sync (0) and async (1) requests, in ns. */
+static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
+
+/* Maximum backwards seek (magic number lifted from CFQ), in KiB. */
+static const int bfq_back_max = 16 * 1024;
+
+/* Penalty of a backwards seek, in number of sectors. */
+static const int bfq_back_penalty = 2;
+
+/* Idling period duration, in ns. */
+static u64 bfq_slice_idle = NSEC_PER_SEC / 125;
+
+/* Minimum number of assigned budgets for which stats are safe to compute. */
+static const int bfq_stats_min_budgets = 194;
+
+/* Default maximum budget values, in sectors and number of requests. */
+static const int bfq_default_max_budget = 16 * 1024;
+
+/*
+ * Async to sync throughput distribution is controlled as follows:
+ * when an async request is served, the entity is charged the number
+ * of sectors of the request, multiplied by the factor below
+ */
+static const int bfq_async_charge_factor = 10;
+
+/* Default timeout values, in jiffies, approximating CFQ defaults. */
+const int bfq_timeout = HZ / 8;
+
+static struct kmem_cache *bfq_pool;
+
+/* Below this threshold (in ns), we consider thinktime immediate. */
+#define BFQ_MIN_TT (2 * NSEC_PER_MSEC)
+
+/* hw_tag detection: parallel requests threshold and min samples needed. */
+#define BFQ_HW_QUEUE_THRESHOLD 4
+#define BFQ_HW_QUEUE_SAMPLES 32
+
+#define BFQQ_SEEK_THR (sector_t)(8 * 100)
+#define BFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
+#define BFQQ_CLOSE_THR (sector_t)(8 * 1024)
+#define BFQQ_SEEKY(bfqq) (hweight32(bfqq->seek_history) > 32/8)
+
+/* Min number of samples required to perform peak-rate update */
+#define BFQ_RATE_MIN_SAMPLES 32
+/* Min observation time interval required to perform a peak-rate update (ns) */
+#define BFQ_RATE_MIN_INTERVAL (300*NSEC_PER_MSEC)
+/* Target observation time interval for a peak-rate update (ns) */
+#define BFQ_RATE_REF_INTERVAL NSEC_PER_SEC
+
+/* Shift used for peak rate fixed precision calculations. */
+#define BFQ_RATE_SHIFT 16
+
+/*
+ * By default, BFQ computes the duration of the weight raising for
+ * interactive applications automatically, using the following formula:
+ * duration = (R / r) * T, where r is the peak rate of the device, and
+ * R and T are two reference parameters.
+ * In particular, R is the peak rate of the reference device (see below),
+ * and T is a reference time: given the systems that are likely to be
+ * installed on the reference device according to its speed class, T is
+ * about the maximum time needed, under BFQ and while reading two files in
+ * parallel, to load typical large applications on these systems.
+ * In practice, the slower/faster the device at hand is, the more/less it
+ * takes to load applications with respect to the reference device.
+ * Accordingly, the longer/shorter BFQ grants weight raising to interactive
+ * applications.
+ *
+ * BFQ uses four different reference pairs (R, T), depending on:
+ * . whether the device is rotational or non-rotational;
+ * . whether the device is slow, such as old or portable HDDs, as well as
+ * SD cards, or fast, such as newer HDDs and SSDs.
+ *
+ * The device's speed class is dynamically (re)detected in
+ * bfq_update_peak_rate() every time the estimated peak rate is updated.
+ *
+ * In the following definitions, R_slow[0]/R_fast[0] and
+ * T_slow[0]/T_fast[0] are the reference values for a slow/fast
+ * rotational device, whereas R_slow[1]/R_fast[1] and
+ * T_slow[1]/T_fast[1] are the reference values for a slow/fast
+ * non-rotational device. Finally, device_speed_thresh are the
+ * thresholds used to switch between speed classes. The reference
+ * rates are not the actual peak rates of the devices used as a
+ * reference, but slightly lower values. The reason for using these
+ * slightly lower values is that the peak-rate estimator tends to
+ * yield slightly lower values than the actual peak rate (it can yield
+ * the actual peak rate only if there is only one process doing I/O,
+ * and the process does sequential I/O).
+ *
+ * Both the reference peak rates and the thresholds are measured in
+ * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
+ */
+static int R_slow[2] = {1000, 10700};
+static int R_fast[2] = {14000, 33000};
+/*
+ * To improve readability, a conversion function is used to initialize the
+ * following arrays, which entails that they can be initialized only in a
+ * function.
+ */
+static int T_slow[2];
+static int T_fast[2];
+static int device_speed_thresh[2];
+
+#define RQ_BIC(rq) ((struct bfq_io_cq *) (rq)->elv.priv[0])
+#define RQ_BFQQ(rq) ((rq)->elv.priv[1])
+
+struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
+{
+ return bic->bfqq[is_sync];
+}
+
+void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync)
+{
+ bic->bfqq[is_sync] = bfqq;
+}
+
+struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
+{
+ return bic->icq.q->elevator->elevator_data;
+}
+
+/**
+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
+ * @icq: the iocontext queue.
+ */
+static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
+{
+ /* bic->icq is the first member, %NULL will convert to %NULL */
+ return container_of(icq, struct bfq_io_cq, icq);
+}
+
+/**
+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
+ * @bfqd: the lookup key.
+ * @ioc: the io_context of the process doing I/O.
+ * @q: the request queue.
+ */
+static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
+ struct io_context *ioc,
+ struct request_queue *q)
+{
+ if (ioc) {
+ unsigned long flags;
+ struct bfq_io_cq *icq;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ icq = icq_to_bic(ioc_lookup_icq(ioc, q));
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return icq;
+ }
+
+ return NULL;
+}
+
+/*
+ * Scheduler run of queue, if there are requests pending and no one in the
+ * driver that will restart queueing.
+ */
+void bfq_schedule_dispatch(struct bfq_data *bfqd)
+{
+ if (bfqd->queued != 0) {
+ bfq_log(bfqd, "schedule dispatch");
+ blk_mq_run_hw_queues(bfqd->queue, true);
+ }
+}
+
+#define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
+#define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
+
+#define bfq_sample_valid(samples) ((samples) > 80)
+
+/*
+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
+ * We choose the request that is closesr to the head right now. Distance
+ * behind the head is penalized and only allowed to a certain extent.
+ */
+static struct request *bfq_choose_req(struct bfq_data *bfqd,
+ struct request *rq1,
+ struct request *rq2,
+ sector_t last)
+{
+ sector_t s1, s2, d1 = 0, d2 = 0;
+ unsigned long back_max;
+#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */
+#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */
+ unsigned int wrap = 0; /* bit mask: requests behind the disk head? */
+
+ if (!rq1 || rq1 == rq2)
+ return rq2;
+ if (!rq2)
+ return rq1;
+
+ if (rq_is_sync(rq1) && !rq_is_sync(rq2))
+ return rq1;
+ else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
+ return rq2;
+ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
+ return rq1;
+ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
+ return rq2;
+
+ s1 = blk_rq_pos(rq1);
+ s2 = blk_rq_pos(rq2);
+
+ /*
+ * By definition, 1KiB is 2 sectors.
+ */
+ back_max = bfqd->bfq_back_max * 2;
+
+ /*
+ * Strict one way elevator _except_ in the case where we allow
+ * short backward seeks which are biased as twice the cost of a
+ * similar forward seek.
+ */
+ if (s1 >= last)
+ d1 = s1 - last;
+ else if (s1 + back_max >= last)
+ d1 = (last - s1) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ1_WRAP;
+
+ if (s2 >= last)
+ d2 = s2 - last;
+ else if (s2 + back_max >= last)
+ d2 = (last - s2) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ2_WRAP;
+
+ /* Found required data */
+
+ /*
+ * By doing switch() on the bit mask "wrap" we avoid having to
+ * check two variables for all permutations: --> faster!
+ */
+ switch (wrap) {
+ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
+ if (d1 < d2)
+ return rq1;
+ else if (d2 < d1)
+ return rq2;
+
+ if (s1 >= s2)
+ return rq1;
+ else
+ return rq2;
+
+ case BFQ_RQ2_WRAP:
+ return rq1;
+ case BFQ_RQ1_WRAP:
+ return rq2;
+ case BFQ_RQ1_WRAP|BFQ_RQ2_WRAP: /* both rqs wrapped */
+ default:
+ /*
+ * Since both rqs are wrapped,
+ * start with the one that's further behind head
+ * (--> only *one* back seek required),
+ * since back seek takes more time than forward.
+ */
+ if (s1 <= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+}
+
+static struct bfq_queue *
+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
+ sector_t sector, struct rb_node **ret_parent,
+ struct rb_node ***rb_link)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *bfqq = NULL;
+
+ parent = NULL;
+ p = &root->rb_node;
+ while (*p) {
+ struct rb_node **n;
+
+ parent = *p;
+ bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+
+ /*
+ * Sort strictly based on sector. Smallest to the left,
+ * largest to the right.
+ */
+ if (sector > blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_right;
+ else if (sector < blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_left;
+ else
+ break;
+ p = n;
+ bfqq = NULL;
+ }
+
+ *ret_parent = parent;
+ if (rb_link)
+ *rb_link = p;
+
+ bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
+ (unsigned long long)sector,
+ bfqq ? bfqq->pid : 0);
+
+ return bfqq;
+}
+
+void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *__bfqq;
+
+ if (bfqq->pos_root) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+
+ if (bfq_class_idle(bfqq))
+ return;
+ if (!bfqq->next_rq)
+ return;
+
+ bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
+ blk_rq_pos(bfqq->next_rq), &parent, &p);
+ if (!__bfqq) {
+ rb_link_node(&bfqq->pos_node, parent, p);
+ rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
+ } else
+ bfqq->pos_root = NULL;
+}
+
+/*
+ * Tell whether there are active queues or groups with differentiated weights.
+ */
+static bool bfq_differentiated_weights(struct bfq_data *bfqd)
+{
+ /*
+ * For weights to differ, at least one of the trees must contain
+ * at least two nodes.
+ */
+ return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
+ (bfqd->queue_weights_tree.rb_node->rb_left ||
+ bfqd->queue_weights_tree.rb_node->rb_right)
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ ) ||
+ (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
+ (bfqd->group_weights_tree.rb_node->rb_left ||
+ bfqd->group_weights_tree.rb_node->rb_right)
+#endif
+ );
+}
+
+/*
+ * The following function returns true if every queue must receive the
+ * same share of the throughput (this condition is used when deciding
+ * whether idling may be disabled, see the comments in the function
+ * bfq_bfqq_may_idle()).
+ *
+ * Such a scenario occurs when:
+ * 1) all active queues have the same weight,
+ * 2) all active groups at the same level in the groups tree have the same
+ * weight,
+ * 3) all active groups at the same level in the groups tree have the same
+ * number of children.
+ *
+ * Unfortunately, keeping the necessary state for evaluating exactly the
+ * above symmetry conditions would be quite complex and time-consuming.
+ * Therefore this function evaluates, instead, the following stronger
+ * sub-conditions, for which it is much easier to maintain the needed
+ * state:
+ * 1) all active queues have the same weight,
+ * 2) all active groups have the same weight,
+ * 3) all active groups have at most one active child each.
+ * In particular, the last two conditions are always true if hierarchical
+ * support and the cgroups interface are not enabled, thus no state needs
+ * to be maintained in this case.
+ */
+static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
+{
+ return !bfq_differentiated_weights(bfqd);
+}
+
+/*
+ * If the weight-counter tree passed as input contains no counter for
+ * the weight of the input entity, then add that counter; otherwise just
+ * increment the existing counter.
+ *
+ * Note that weight-counter trees contain few nodes in mostly symmetric
+ * scenarios. For example, if all queues have the same weight, then the
+ * weight-counter tree for the queues may contain at most one node.
+ * This holds even if low_latency is on, because weight-raised queues
+ * are not inserted in the tree.
+ * In most scenarios, the rate at which nodes are created/destroyed
+ * should be low too.
+ */
+void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
+ struct rb_root *root)
+{
+ struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+ /*
+ * Do not insert if the entity is already associated with a
+ * counter, which happens if:
+ * 1) the entity is associated with a queue,
+ * 2) a request arrival has caused the queue to become both
+ * non-weight-raised, and hence change its weight, and
+ * backlogged; in this respect, each of the two events
+ * causes an invocation of this function,
+ * 3) this is the invocation of this function caused by the
+ * second event. This second invocation is actually useless,
+ * and we handle this fact by exiting immediately. More
+ * efficient or clearer solutions might possibly be adopted.
+ */
+ if (entity->weight_counter)
+ return;
+
+ while (*new) {
+ struct bfq_weight_counter *__counter = container_of(*new,
+ struct bfq_weight_counter,
+ weights_node);
+ parent = *new;
+
+ if (entity->weight == __counter->weight) {
+ entity->weight_counter = __counter;
+ goto inc_counter;
+ }
+ if (entity->weight < __counter->weight)
+ new = &((*new)->rb_left);
+ else
+ new = &((*new)->rb_right);
+ }
+
+ entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
+ GFP_ATOMIC);
+
+ /*
+ * In the unlucky event of an allocation failure, we just
+ * exit. This will cause the weight of entity to not be
+ * considered in bfq_differentiated_weights, which, in its
+ * turn, causes the scenario to be deemed wrongly symmetric in
+ * case entity's weight would have been the only weight making
+ * the scenario asymmetric. On the bright side, no unbalance
+ * will however occur when entity becomes inactive again (the
+ * invocation of this function is triggered by an activation
+ * of entity). In fact, bfq_weights_tree_remove does nothing
+ * if !entity->weight_counter.
+ */
+ if (unlikely(!entity->weight_counter))
+ return;
+
+ entity->weight_counter->weight = entity->weight;
+ rb_link_node(&entity->weight_counter->weights_node, parent, new);
+ rb_insert_color(&entity->weight_counter->weights_node, root);
+
+inc_counter:
+ entity->weight_counter->num_active++;
+}
+
+/*
+ * Decrement the weight counter associated with the entity, and, if the
+ * counter reaches 0, remove the counter from the tree.
+ * See the comments to the function bfq_weights_tree_add() for considerations
+ * about overhead.
+ */
+void bfq_weights_tree_remove(struct bfq_data *bfqd, struct bfq_entity *entity,
+ struct rb_root *root)
+{
+ if (!entity->weight_counter)
+ return;
+
+ entity->weight_counter->num_active--;
+ if (entity->weight_counter->num_active > 0)
+ goto reset_entity_pointer;
+
+ rb_erase(&entity->weight_counter->weights_node, root);
+ kfree(entity->weight_counter);
+
+reset_entity_pointer:
+ entity->weight_counter = NULL;
+}
+
+/*
+ * Return expired entry, or NULL to just start from scratch in rbtree.
+ */
+static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
+ struct request *last)
+{
+ struct request *rq;
+
+ if (bfq_bfqq_fifo_expire(bfqq))
+ return NULL;
+
+ bfq_mark_bfqq_fifo_expire(bfqq);
+
+ rq = rq_entry_fifo(bfqq->fifo.next);
+
+ if (rq == last || ktime_get_ns() < rq->fifo_time)
+ return NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "check_fifo: returned %p", rq);
+ return rq;
+}
+
+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *last)
+{
+ struct rb_node *rbnext = rb_next(&last->rb_node);
+ struct rb_node *rbprev = rb_prev(&last->rb_node);
+ struct request *next, *prev = NULL;
+
+ /* Follow expired path, else get first next available. */
+ next = bfq_check_fifo(bfqq, last);
+ if (next)
+ return next;
+
+ if (rbprev)
+ prev = rb_entry_rq(rbprev);
+
+ if (rbnext)
+ next = rb_entry_rq(rbnext);
+ else {
+ rbnext = rb_first(&bfqq->sort_list);
+ if (rbnext && rbnext != &last->rb_node)
+ next = rb_entry_rq(rbnext);
+ }
+
+ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
+}
+
+/* see the definition of bfq_async_charge_factor for details */
+static unsigned long bfq_serv_to_charge(struct request *rq,
+ struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1)
+ return blk_rq_sectors(rq);
+
+ /*
+ * If there are no weight-raised queues, then amplify service
+ * by just the async charge factor; otherwise amplify service
+ * by twice the async charge factor, to further reduce latency
+ * for weight-raised queues.
+ */
+ if (bfqq->bfqd->wr_busy_queues == 0)
+ return blk_rq_sectors(rq) * bfq_async_charge_factor;
+
+ return blk_rq_sectors(rq) * 2 * bfq_async_charge_factor;
+}
+
+/**
+ * bfq_updated_next_req - update the queue after a new next_rq selection.
+ * @bfqd: the device data the queue belongs to.
+ * @bfqq: the queue to update.
+ *
+ * If the first request of a queue changes we make sure that the queue
+ * has enough budget to serve at least its first request (if the
+ * request has grown). We do this because if the queue has not enough
+ * budget for its first request, it has to go through two dispatch
+ * rounds to actually get it dispatched.
+ */
+static void bfq_updated_next_req(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct request *next_rq = bfqq->next_rq;
+ unsigned long new_budget;
+
+ if (!next_rq)
+ return;
+
+ if (bfqq == bfqd->in_service_queue)
+ /*
+ * In order not to break guarantees, budgets cannot be
+ * changed after an entity has been selected.
+ */
+ return;
+
+ new_budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ if (entity->budget != new_budget) {
+ entity->budget = new_budget;
+ bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
+ new_budget);
+ bfq_requeue_bfqq(bfqd, bfqq);
+ }
+}
+
+static void
+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
+{
+ if (bic->saved_idle_window)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+
+ if (bic->saved_IO_bound)
+ bfq_mark_bfqq_IO_bound(bfqq);
+ else
+ bfq_clear_bfqq_IO_bound(bfqq);
+
+ bfqq->ttime = bic->saved_ttime;
+ bfqq->wr_coeff = bic->saved_wr_coeff;
+ bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
+ bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
+ bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
+
+ if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
+ time_is_before_jiffies(bfqq->last_wr_start_finish +
+ bfqq->wr_cur_max_time))) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "resume state: switching off wr");
+
+ bfqq->wr_coeff = 1;
+ }
+
+ /* make sure weight will be updated, however we got here */
+ bfqq->entity.prio_changed = 1;
+}
+
+static int bfqq_process_refs(struct bfq_queue *bfqq)
+{
+ return bfqq->ref - bfqq->allocated - bfqq->entity.on_st;
+}
+
+/* Empty burst list and add just bfqq (see comments on bfq_handle_burst) */
+static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_queue *item;
+ struct hlist_node *n;
+
+ hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
+ hlist_del_init(&item->burst_list_node);
+ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+ bfqd->burst_size = 1;
+ bfqd->burst_parent_entity = bfqq->entity.parent;
+}
+
+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ /* Increment burst size to take into account also bfqq */
+ bfqd->burst_size++;
+
+ if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
+ struct bfq_queue *pos, *bfqq_item;
+ struct hlist_node *n;
+
+ /*
+ * Enough queues have been activated shortly after each
+ * other to consider this burst as large.
+ */
+ bfqd->large_burst = true;
+
+ /*
+ * We can now mark all queues in the burst list as
+ * belonging to a large burst.
+ */
+ hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
+ burst_list_node)
+ bfq_mark_bfqq_in_large_burst(bfqq_item);
+ bfq_mark_bfqq_in_large_burst(bfqq);
+
+ /*
+ * From now on, and until the current burst finishes, any
+ * new queue being activated shortly after the last queue
+ * was inserted in the burst can be immediately marked as
+ * belonging to a large burst. So the burst list is not
+ * needed any more. Remove it.
+ */
+ hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
+ burst_list_node)
+ hlist_del_init(&pos->burst_list_node);
+ } else /*
+ * Burst not yet large: add bfqq to the burst list. Do
+ * not increment the ref counter for bfqq, because bfqq
+ * is removed from the burst list before freeing bfqq
+ * in put_queue.
+ */
+ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+}
+
+/*
+ * If many queues belonging to the same group happen to be created
+ * shortly after each other, then the processes associated with these
+ * queues have typically a common goal. In particular, bursts of queue
+ * creations are usually caused by services or applications that spawn
+ * many parallel threads/processes. Examples are systemd during boot,
+ * or git grep. To help these processes get their job done as soon as
+ * possible, it is usually better to not grant either weight-raising
+ * or device idling to their queues.
+ *
+ * In this comment we describe, firstly, the reasons why this fact
+ * holds, and, secondly, the next function, which implements the main
+ * steps needed to properly mark these queues so that they can then be
+ * treated in a different way.
+ *
+ * The above services or applications benefit mostly from a high
+ * throughput: the quicker the requests of the activated queues are
+ * cumulatively served, the sooner the target job of these queues gets
+ * completed. As a consequence, weight-raising any of these queues,
+ * which also implies idling the device for it, is almost always
+ * counterproductive. In most cases it just lowers throughput.
+ *
+ * On the other hand, a burst of queue creations may be caused also by
+ * the start of an application that does not consist of a lot of
+ * parallel I/O-bound threads. In fact, with a complex application,
+ * several short processes may need to be executed to start-up the
+ * application. In this respect, to start an application as quickly as
+ * possible, the best thing to do is in any case to privilege the I/O
+ * related to the application with respect to all other
+ * I/O. Therefore, the best strategy to start as quickly as possible
+ * an application that causes a burst of queue creations is to
+ * weight-raise all the queues created during the burst. This is the
+ * exact opposite of the best strategy for the other type of bursts.
+ *
+ * In the end, to take the best action for each of the two cases, the
+ * two types of bursts need to be distinguished. Fortunately, this
+ * seems relatively easy, by looking at the sizes of the bursts. In
+ * particular, we found a threshold such that only bursts with a
+ * larger size than that threshold are apparently caused by
+ * services or commands such as systemd or git grep. For brevity,
+ * hereafter we call just 'large' these bursts. BFQ *does not*
+ * weight-raise queues whose creation occurs in a large burst. In
+ * addition, for each of these queues BFQ performs or does not perform
+ * idling depending on which choice boosts the throughput more. The
+ * exact choice depends on the device and request pattern at
+ * hand.
+ *
+ * Unfortunately, false positives may occur while an interactive task
+ * is starting (e.g., an application is being started). The
+ * consequence is that the queues associated with the task do not
+ * enjoy weight raising as expected. Fortunately these false positives
+ * are very rare. They typically occur if some service happens to
+ * start doing I/O exactly when the interactive task starts.
+ *
+ * Turning back to the next function, it implements all the steps
+ * needed to detect the occurrence of a large burst and to properly
+ * mark all the queues belonging to it (so that they can then be
+ * treated in a different way). This goal is achieved by maintaining a
+ * "burst list" that holds, temporarily, the queues that belong to the
+ * burst in progress. The list is then used to mark these queues as
+ * belonging to a large burst if the burst does become large. The main
+ * steps are the following.
+ *
+ * . when the very first queue is created, the queue is inserted into the
+ * list (as it could be the first queue in a possible burst)
+ *
+ * . if the current burst has not yet become large, and a queue Q that does
+ * not yet belong to the burst is activated shortly after the last time
+ * at which a new queue entered the burst list, then the function appends
+ * Q to the burst list
+ *
+ * . if, as a consequence of the previous step, the burst size reaches
+ * the large-burst threshold, then
+ *
+ * . all the queues in the burst list are marked as belonging to a
+ * large burst
+ *
+ * . the burst list is deleted; in fact, the burst list already served
+ * its purpose (keeping temporarily track of the queues in a burst,
+ * so as to be able to mark them as belonging to a large burst in the
+ * previous sub-step), and now is not needed any more
+ *
+ * . the device enters a large-burst mode
+ *
+ * . if a queue Q that does not belong to the burst is created while
+ * the device is in large-burst mode and shortly after the last time
+ * at which a queue either entered the burst list or was marked as
+ * belonging to the current large burst, then Q is immediately marked
+ * as belonging to a large burst.
+ *
+ * . if a queue Q that does not belong to the burst is created a while
+ * later, i.e., not shortly after, than the last time at which a queue
+ * either entered the burst list or was marked as belonging to the
+ * current large burst, then the current burst is deemed as finished and:
+ *
+ * . the large-burst mode is reset if set
+ *
+ * . the burst list is emptied
+ *
+ * . Q is inserted in the burst list, as Q may be the first queue
+ * in a possible new burst (then the burst list contains just Q
+ * after this step).
+ */
+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ /*
+ * If bfqq is already in the burst list or is part of a large
+ * burst, or finally has just been split, then there is
+ * nothing else to do.
+ */
+ if (!hlist_unhashed(&bfqq->burst_list_node) ||
+ bfq_bfqq_in_large_burst(bfqq) ||
+ time_is_after_eq_jiffies(bfqq->split_time +
+ msecs_to_jiffies(10)))
+ return;
+
+ /*
+ * If bfqq's creation happens late enough, or bfqq belongs to
+ * a different group than the burst group, then the current
+ * burst is finished, and related data structures must be
+ * reset.
+ *
+ * In this respect, consider the special case where bfqq is
+ * the very first queue created after BFQ is selected for this
+ * device. In this case, last_ins_in_burst and
+ * burst_parent_entity are not yet significant when we get
+ * here. But it is easy to verify that, whether or not the
+ * following condition is true, bfqq will end up being
+ * inserted into the burst list. In particular the list will
+ * happen to contain only bfqq. And this is exactly what has
+ * to happen, as bfqq may be the first queue of the first
+ * burst.
+ */
+ if (time_is_before_jiffies(bfqd->last_ins_in_burst +
+ bfqd->bfq_burst_interval) ||
+ bfqq->entity.parent != bfqd->burst_parent_entity) {
+ bfqd->large_burst = false;
+ bfq_reset_burst_list(bfqd, bfqq);
+ goto end;
+ }
+
+ /*
+ * If we get here, then bfqq is being activated shortly after the
+ * last queue. So, if the current burst is also large, we can mark
+ * bfqq as belonging to this large burst immediately.
+ */
+ if (bfqd->large_burst) {
+ bfq_mark_bfqq_in_large_burst(bfqq);
+ goto end;
+ }
+
+ /*
+ * If we get here, then a large-burst state has not yet been
+ * reached, but bfqq is being activated shortly after the last
+ * queue. Then we add bfqq to the burst.
+ */
+ bfq_add_to_burst(bfqd, bfqq);
+end:
+ /*
+ * At this point, bfqq either has been added to the current
+ * burst or has caused the current burst to terminate and a
+ * possible new burst to start. In particular, in the second
+ * case, bfqq has become the first queue in the possible new
+ * burst. In both cases last_ins_in_burst needs to be moved
+ * forward.
+ */
+ bfqd->last_ins_in_burst = jiffies;
+}
+
+static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ return entity->budget - entity->service;
+}
+
+/*
+ * If enough samples have been computed, return the current max budget
+ * stored in bfqd, which is dynamically updated according to the
+ * estimated disk peak rate; otherwise return the default max budget
+ */
+static int bfq_max_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < bfq_stats_min_budgets)
+ return bfq_default_max_budget;
+ else
+ return bfqd->bfq_max_budget;
+}
+
+/*
+ * Return min budget, which is a fraction of the current or default
+ * max budget (trying with 1/32)
+ */
+static int bfq_min_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < bfq_stats_min_budgets)
+ return bfq_default_max_budget / 32;
+ else
+ return bfqd->bfq_max_budget / 32;
+}
+
+/*
+ * The next function, invoked after the input queue bfqq switches from
+ * idle to busy, updates the budget of bfqq. The function also tells
+ * whether the in-service queue should be expired, by returning
+ * true. The purpose of expiring the in-service queue is to give bfqq
+ * the chance to possibly preempt the in-service queue, and the reason
+ * for preempting the in-service queue is to achieve one of the two
+ * goals below.
+ *
+ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
+ * expired because it has remained idle. In particular, bfqq may have
+ * expired for one of the following two reasons:
+ *
+ * - BFQQE_NO_MORE_REQUESTS bfqq did not enjoy any device idling
+ * and did not make it to issue a new request before its last
+ * request was served;
+ *
+ * - BFQQE_TOO_IDLE bfqq did enjoy device idling, but did not issue
+ * a new request before the expiration of the idling-time.
+ *
+ * Even if bfqq has expired for one of the above reasons, the process
+ * associated with the queue may be however issuing requests greedily,
+ * and thus be sensitive to the bandwidth it receives (bfqq may have
+ * remained idle for other reasons: CPU high load, bfqq not enjoying
+ * idling, I/O throttling somewhere in the path from the process to
+ * the I/O scheduler, ...). But if, after every expiration for one of
+ * the above two reasons, bfqq has to wait for the service of at least
+ * one full budget of another queue before being served again, then
+ * bfqq is likely to get a much lower bandwidth or resource time than
+ * its reserved ones. To address this issue, two countermeasures need
+ * to be taken.
+ *
+ * First, the budget and the timestamps of bfqq need to be updated in
+ * a special way on bfqq reactivation: they need to be updated as if
+ * bfqq did not remain idle and did not expire. In fact, if they are
+ * computed as if bfqq expired and remained idle until reactivation,
+ * then the process associated with bfqq is treated as if, instead of
+ * being greedy, it stopped issuing requests when bfqq remained idle,
+ * and restarts issuing requests only on this reactivation. In other
+ * words, the scheduler does not help the process recover the "service
+ * hole" between bfqq expiration and reactivation. As a consequence,
+ * the process receives a lower bandwidth than its reserved one. In
+ * contrast, to recover this hole, the budget must be updated as if
+ * bfqq was not expired at all before this reactivation, i.e., it must
+ * be set to the value of the remaining budget when bfqq was
+ * expired. Along the same line, timestamps need to be assigned the
+ * value they had the last time bfqq was selected for service, i.e.,
+ * before last expiration. Thus timestamps need to be back-shifted
+ * with respect to their normal computation (see [1] for more details
+ * on this tricky aspect).
+ *
+ * Secondly, to allow the process to recover the hole, the in-service
+ * queue must be expired too, to give bfqq the chance to preempt it
+ * immediately. In fact, if bfqq has to wait for a full budget of the
+ * in-service queue to be completed, then it may become impossible to
+ * let the process recover the hole, even if the back-shifted
+ * timestamps of bfqq are lower than those of the in-service queue. If
+ * this happens for most or all of the holes, then the process may not
+ * receive its reserved bandwidth. In this respect, it is worth noting
+ * that, being the service of outstanding requests unpreemptible, a
+ * little fraction of the holes may however be unrecoverable, thereby
+ * causing a little loss of bandwidth.
+ *
+ * The last important point is detecting whether bfqq does need this
+ * bandwidth recovery. In this respect, the next function deems the
+ * process associated with bfqq greedy, and thus allows it to recover
+ * the hole, if: 1) the process is waiting for the arrival of a new
+ * request (which implies that bfqq expired for one of the above two
+ * reasons), and 2) such a request has arrived soon. The first
+ * condition is controlled through the flag non_blocking_wait_rq,
+ * while the second through the flag arrived_in_time. If both
+ * conditions hold, then the function computes the budget in the
+ * above-described special way, and signals that the in-service queue
+ * should be expired. Timestamp back-shifting is done later in
+ * __bfq_activate_entity.
+ *
+ * 2. Reduce latency. Even if timestamps are not backshifted to let
+ * the process associated with bfqq recover a service hole, bfqq may
+ * however happen to have, after being (re)activated, a lower finish
+ * timestamp than the in-service queue. That is, the next budget of
+ * bfqq may have to be completed before the one of the in-service
+ * queue. If this is the case, then preempting the in-service queue
+ * allows this goal to be achieved, apart from the unpreemptible,
+ * outstanding requests mentioned above.
+ *
+ * Unfortunately, regardless of which of the above two goals one wants
+ * to achieve, service trees need first to be updated to know whether
+ * the in-service queue must be preempted. To have service trees
+ * correctly updated, the in-service queue must be expired and
+ * rescheduled, and bfqq must be scheduled too. This is one of the
+ * most costly operations (in future versions, the scheduling
+ * mechanism may be re-designed in such a way to make it possible to
+ * know whether preemption is needed without needing to update service
+ * trees). In addition, queue preemptions almost always cause random
+ * I/O, and thus loss of throughput. Because of these facts, the next
+ * function adopts the following simple scheme to avoid both costly
+ * operations and too frequent preemptions: it requests the expiration
+ * of the in-service queue (unconditionally) only for queues that need
+ * to recover a hole, or that either are weight-raised or deserve to
+ * be weight-raised.
+ */
+static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ bool arrived_in_time,
+ bool wr_or_deserves_wr)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) {
+ /*
+ * We do not clear the flag non_blocking_wait_rq here, as
+ * the latter is used in bfq_activate_bfqq to signal
+ * that timestamps need to be back-shifted (and is
+ * cleared right after).
+ */
+
+ /*
+ * In next assignment we rely on that either
+ * entity->service or entity->budget are not updated
+ * on expiration if bfqq is empty (see
+ * __bfq_bfqq_recalc_budget). Thus both quantities
+ * remain unchanged after such an expiration, and the
+ * following statement therefore assigns to
+ * entity->budget the remaining budget on such an
+ * expiration. For clarity, entity->service is not
+ * updated on expiration in any case, and, in normal
+ * operation, is reset only when bfqq is selected for
+ * service (see bfq_get_next_queue).
+ */
+ entity->budget = min_t(unsigned long,
+ bfq_bfqq_budget_left(bfqq),
+ bfqq->max_budget);
+
+ return true;
+ }
+
+ entity->budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(bfqq->next_rq, bfqq));
+ bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
+ return wr_or_deserves_wr;
+}
+
+static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
+{
+ u64 dur;
+
+ if (bfqd->bfq_wr_max_time > 0)
+ return bfqd->bfq_wr_max_time;
+
+ dur = bfqd->RT_prod;
+ do_div(dur, bfqd->peak_rate);
+
+ /*
+ * Limit duration between 3 and 13 seconds. Tests show that
+ * higher values than 13 seconds often yield the opposite of
+ * the desired result, i.e., worsen responsiveness by letting
+ * non-interactive and non-soft-real-time applications
+ * preserve weight raising for a too long time interval.
+ *
+ * On the other end, lower values than 3 seconds make it
+ * difficult for most interactive tasks to complete their jobs
+ * before weight-raising finishes.
+ */
+ if (dur > msecs_to_jiffies(13000))
+ dur = msecs_to_jiffies(13000);
+ else if (dur < msecs_to_jiffies(3000))
+ dur = msecs_to_jiffies(3000);
+
+ return dur;
+}
+
+static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ unsigned int old_wr_coeff,
+ bool wr_or_deserves_wr,
+ bool interactive,
+ bool in_burst,
+ bool soft_rt)
+{
+ if (old_wr_coeff == 1 && wr_or_deserves_wr) {
+ /* start a weight-raising period */
+ if (interactive) {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ } else {
+ bfqq->wr_start_at_switch_to_srt = jiffies;
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff *
+ BFQ_SOFTRT_WEIGHT_FACTOR;
+ bfqq->wr_cur_max_time =
+ bfqd->bfq_wr_rt_max_time;
+ }
+
+ /*
+ * If needed, further reduce budget to make sure it is
+ * close to bfqq's backlog, so as to reduce the
+ * scheduling-error component due to a too large
+ * budget. Do not care about throughput consequences,
+ * but only about latency. Finally, do not assign a
+ * too small budget either, to avoid increasing
+ * latency by causing too frequent expirations.
+ */
+ bfqq->entity.budget = min_t(unsigned long,
+ bfqq->entity.budget,
+ 2 * bfq_min_budget(bfqd));
+ } else if (old_wr_coeff > 1) {
+ if (interactive) { /* update wr coeff and duration */
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ } else if (in_burst)
+ bfqq->wr_coeff = 1;
+ else if (soft_rt) {
+ /*
+ * The application is now or still meeting the
+ * requirements for being deemed soft rt. We
+ * can then correctly and safely (re)charge
+ * the weight-raising duration for the
+ * application with the weight-raising
+ * duration for soft rt applications.
+ *
+ * In particular, doing this recharge now, i.e.,
+ * before the weight-raising period for the
+ * application finishes, reduces the probability
+ * of the following negative scenario:
+ * 1) the weight of a soft rt application is
+ * raised at startup (as for any newly
+ * created application),
+ * 2) since the application is not interactive,
+ * at a certain time weight-raising is
+ * stopped for the application,
+ * 3) at that time the application happens to
+ * still have pending requests, and hence
+ * is destined to not have a chance to be
+ * deemed soft rt before these requests are
+ * completed (see the comments to the
+ * function bfq_bfqq_softrt_next_start()
+ * for details on soft rt detection),
+ * 4) these pending requests experience a high
+ * latency because the application is not
+ * weight-raised while they are pending.
+ */
+ if (bfqq->wr_cur_max_time !=
+ bfqd->bfq_wr_rt_max_time) {
+ bfqq->wr_start_at_switch_to_srt =
+ bfqq->last_wr_start_finish;
+
+ bfqq->wr_cur_max_time =
+ bfqd->bfq_wr_rt_max_time;
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff *
+ BFQ_SOFTRT_WEIGHT_FACTOR;
+ }
+ bfqq->last_wr_start_finish = jiffies;
+ }
+ }
+}
+
+static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ return bfqq->dispatched == 0 &&
+ time_is_before_jiffies(
+ bfqq->budget_timeout +
+ bfqd->bfq_wr_min_idle_time);
+}
+
+static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ int old_wr_coeff,
+ struct request *rq,
+ bool *interactive)
+{
+ bool soft_rt, in_burst, wr_or_deserves_wr,
+ bfqq_wants_to_preempt,
+ idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
+ /*
+ * See the comments on
+ * bfq_bfqq_update_budg_for_activation for
+ * details on the usage of the next variable.
+ */
+ arrived_in_time = ktime_get_ns() <=
+ bfqq->ttime.last_end_request +
+ bfqd->bfq_slice_idle * 3;
+
+ bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags);
+
+ /*
+ * bfqq deserves to be weight-raised if:
+ * - it is sync,
+ * - it does not belong to a large burst,
+ * - it has been idle for enough time or is soft real-time,
+ * - is linked to a bfq_io_cq (it is not shared in any sense).
+ */
+ in_burst = bfq_bfqq_in_large_burst(bfqq);
+ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
+ !in_burst &&
+ time_is_before_jiffies(bfqq->soft_rt_next_start);
+ *interactive = !in_burst && idle_for_long_time;
+ wr_or_deserves_wr = bfqd->low_latency &&
+ (bfqq->wr_coeff > 1 ||
+ (bfq_bfqq_sync(bfqq) &&
+ bfqq->bic && (*interactive || soft_rt)));
+
+ /*
+ * Using the last flag, update budget and check whether bfqq
+ * may want to preempt the in-service queue.
+ */
+ bfqq_wants_to_preempt =
+ bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
+ arrived_in_time,
+ wr_or_deserves_wr);
+
+ /*
+ * If bfqq happened to be activated in a burst, but has been
+ * idle for much more than an interactive queue, then we
+ * assume that, in the overall I/O initiated in the burst, the
+ * I/O associated with bfqq is finished. So bfqq does not need
+ * to be treated as a queue belonging to a burst
+ * anymore. Accordingly, we reset bfqq's in_large_burst flag
+ * if set, and remove bfqq from the burst list if it's
+ * there. We do not decrement burst_size, because the fact
+ * that bfqq does not need to belong to the burst list any
+ * more does not invalidate the fact that bfqq was created in
+ * a burst.
+ */
+ if (likely(!bfq_bfqq_just_created(bfqq)) &&
+ idle_for_long_time &&
+ time_is_before_jiffies(
+ bfqq->budget_timeout +
+ msecs_to_jiffies(10000))) {
+ hlist_del_init(&bfqq->burst_list_node);
+ bfq_clear_bfqq_in_large_burst(bfqq);
+ }
+
+ bfq_clear_bfqq_just_created(bfqq);
+
+
+ if (!bfq_bfqq_IO_bound(bfqq)) {
+ if (arrived_in_time) {
+ bfqq->requests_within_timer++;
+ if (bfqq->requests_within_timer >=
+ bfqd->bfq_requests_within_timer)
+ bfq_mark_bfqq_IO_bound(bfqq);
+ } else
+ bfqq->requests_within_timer = 0;
+ }
+
+ if (bfqd->low_latency) {
+ if (unlikely(time_is_after_jiffies(bfqq->split_time)))
+ /* wraparound */
+ bfqq->split_time =
+ jiffies - bfqd->bfq_wr_min_idle_time - 1;
+
+ if (time_is_before_jiffies(bfqq->split_time +
+ bfqd->bfq_wr_min_idle_time)) {
+ bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
+ old_wr_coeff,
+ wr_or_deserves_wr,
+ *interactive,
+ in_burst,
+ soft_rt);
+
+ if (old_wr_coeff != bfqq->wr_coeff)
+ bfqq->entity.prio_changed = 1;
+ }
+ }
+
+ bfqq->last_idle_bklogged = jiffies;
+ bfqq->service_from_backlogged = 0;
+ bfq_clear_bfqq_softrt_update(bfqq);
+
+ bfq_add_bfqq_busy(bfqd, bfqq);
+
+ /*
+ * Expire in-service queue only if preemption may be needed
+ * for guarantees. In this respect, the function
+ * next_queue_may_preempt just checks a simple, necessary
+ * condition, and not a sufficient condition based on
+ * timestamps. In fact, for the latter condition to be
+ * evaluated, timestamps would need first to be updated, and
+ * this operation is quite costly (see the comments on the
+ * function bfq_bfqq_update_budg_for_activation).
+ */
+ if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
+ bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff &&
+ next_queue_may_preempt(bfqd))
+ bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
+ false, BFQQE_PREEMPTED);
+}
+
+static void bfq_add_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *next_rq, *prev;
+ unsigned int old_wr_coeff = bfqq->wr_coeff;
+ bool interactive = false;
+
+ bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq));
+ bfqq->queued[rq_is_sync(rq)]++;
+ bfqd->queued++;
+
+ elv_rb_add(&bfqq->sort_list, rq);
+
+ /*
+ * Check if this request is a better next-serve candidate.
+ */
+ prev = bfqq->next_rq;
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
+ bfqq->next_rq = next_rq;
+
+ /*
+ * Adjust priority tree position, if next_rq changes.
+ */
+ if (prev != bfqq->next_rq)
+ bfq_pos_tree_add_move(bfqd, bfqq);
+
+ if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
+ bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
+ rq, &interactive);
+ else {
+ if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
+ time_is_before_jiffies(
+ bfqq->last_wr_start_finish +
+ bfqd->bfq_wr_min_inter_arr_async)) {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+
+ bfqd->wr_busy_queues++;
+ bfqq->entity.prio_changed = 1;
+ }
+ if (prev != bfqq->next_rq)
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ /*
+ * Assign jiffies to last_wr_start_finish in the following
+ * cases:
+ *
+ * . if bfqq is not going to be weight-raised, because, for
+ * non weight-raised queues, last_wr_start_finish stores the
+ * arrival time of the last request; as of now, this piece
+ * of information is used only for deciding whether to
+ * weight-raise async queues
+ *
+ * . if bfqq is not weight-raised, because, if bfqq is now
+ * switching to weight-raised, then last_wr_start_finish
+ * stores the time when weight-raising starts
+ *
+ * . if bfqq is interactive, because, regardless of whether
+ * bfqq is currently weight-raised, the weight-raising
+ * period must start or restart (this case is considered
+ * separately because it is not detected by the above
+ * conditions, if bfqq is already weight-raised)
+ *
+ * last_wr_start_finish has to be updated also if bfqq is soft
+ * real-time, because the weight-raising period is constantly
+ * restarted on idle-to-busy transitions for these queues, but
+ * this is already done in bfq_bfqq_handle_idle_busy_switch if
+ * needed.
+ */
+ if (bfqd->low_latency &&
+ (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
+ bfqq->last_wr_start_finish = jiffies;
+}
+
+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
+ struct bio *bio,
+ struct request_queue *q)
+{
+ struct bfq_queue *bfqq = bfqd->bio_bfqq;
+
+
+ if (bfqq)
+ return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
+
+ return NULL;
+}
+
+static sector_t get_sdist(sector_t last_pos, struct request *rq)
+{
+ if (last_pos)
+ return abs(blk_rq_pos(rq) - last_pos);
+
+ return 0;
+}
+
+#if 0 /* Still not clear if we can do without next two functions */
+static void bfq_activate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ bfqd->rq_in_driver++;
+}
+
+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ bfqd->rq_in_driver--;
+}
+#endif
+
+static void bfq_remove_request(struct request_queue *q,
+ struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ const int sync = rq_is_sync(rq);
+
+ if (bfqq->next_rq == rq) {
+ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ if (rq->queuelist.prev != &rq->queuelist)
+ list_del_init(&rq->queuelist);
+ bfqq->queued[sync]--;
+ bfqd->queued--;
+ elv_rb_del(&bfqq->sort_list, rq);
+
+ elv_rqhash_del(q, rq);
+ if (q->last_merge == rq)
+ q->last_merge = NULL;
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ bfqq->next_rq = NULL;
+
+ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
+ bfq_del_bfqq_busy(bfqd, bfqq, false);
+ /*
+ * bfqq emptied. In normal operation, when
+ * bfqq is empty, bfqq->entity.service and
+ * bfqq->entity.budget must contain,
+ * respectively, the service received and the
+ * budget used last time bfqq emptied. These
+ * facts do not hold in this case, as at least
+ * this last removal occurred while bfqq is
+ * not in service. To avoid inconsistencies,
+ * reset both bfqq->entity.service and
+ * bfqq->entity.budget, if bfqq has still a
+ * process that may issue I/O requests to it.
+ */
+ bfqq->entity.budget = bfqq->entity.service = 0;
+ }
+
+ /*
+ * Remove queue from request-position tree as it is empty.
+ */
+ if (bfqq->pos_root) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+ }
+
+ if (rq->cmd_flags & REQ_META)
+ bfqq->meta_pending--;
+
+ bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
+}
+
+static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
+{
+ struct request_queue *q = hctx->queue;
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct request *free = NULL;
+ /*
+ * bfq_bic_lookup grabs the queue_lock: invoke it now and
+ * store its return value for later use, to avoid nesting
+ * queue_lock inside the bfqd->lock. We assume that the bic
+ * returned by bfq_bic_lookup does not go away before
+ * bfqd->lock is taken.
+ */
+ struct bfq_io_cq *bic = bfq_bic_lookup(bfqd, current->io_context, q);
+ bool ret;
+
+ spin_lock_irq(&bfqd->lock);
+
+ if (bic)
+ bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
+ else
+ bfqd->bio_bfqq = NULL;
+ bfqd->bio_bic = bic;
+
+ ret = blk_mq_sched_try_merge(q, bio, &free);
+
+ if (free)
+ blk_mq_free_request(free);
+ spin_unlock_irq(&bfqd->lock);
+
+ return ret;
+}
+
+static int bfq_request_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct request *__rq;
+
+ __rq = bfq_find_rq_fmerge(bfqd, bio, q);
+ if (__rq && elv_bio_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+
+ return ELEVATOR_NO_MERGE;
+}
+
+static void bfq_request_merged(struct request_queue *q, struct request *req,
+ enum elv_merge type)
+{
+ if (type == ELEVATOR_FRONT_MERGE &&
+ rb_prev(&req->rb_node) &&
+ blk_rq_pos(req) <
+ blk_rq_pos(container_of(rb_prev(&req->rb_node),
+ struct request, rb_node))) {
+ struct bfq_queue *bfqq = RQ_BFQQ(req);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *prev, *next_rq;
+
+ /* Reposition request in its sort_list */
+ elv_rb_del(&bfqq->sort_list, req);
+ elv_rb_add(&bfqq->sort_list, req);
+
+ /* Choose next request to be served for bfqq */
+ prev = bfqq->next_rq;
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
+ bfqd->last_position);
+ bfqq->next_rq = next_rq;
+ /*
+ * If next_rq changes, update both the queue's budget to
+ * fit the new request and the queue's position in its
+ * rq_pos_tree.
+ */
+ if (prev != bfqq->next_rq) {
+ bfq_updated_next_req(bfqd, bfqq);
+ bfq_pos_tree_add_move(bfqd, bfqq);
+ }
+ }
+}
+
+static void bfq_requests_merged(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
+
+ if (!RB_EMPTY_NODE(&rq->rb_node))
+ goto end;
+ spin_lock_irq(&bfqq->bfqd->lock);
+
+ /*
+ * If next and rq belong to the same bfq_queue and next is older
+ * than rq, then reposition rq in the fifo (by substituting next
+ * with rq). Otherwise, if next and rq belong to different
+ * bfq_queues, never reposition rq: in fact, we would have to
+ * reposition it with respect to next's position in its own fifo,
+ * which would most certainly be too expensive with respect to
+ * the benefits.
+ */
+ if (bfqq == next_bfqq &&
+ !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
+ next->fifo_time < rq->fifo_time) {
+ list_del_init(&rq->queuelist);
+ list_replace_init(&next->queuelist, &rq->queuelist);
+ rq->fifo_time = next->fifo_time;
+ }
+
+ if (bfqq->next_rq == next)
+ bfqq->next_rq = rq;
+
+ bfq_remove_request(q, next);
+
+ spin_unlock_irq(&bfqq->bfqd->lock);
+end:
+ bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
+}
+
+/* Must be called with bfqq != NULL */
+static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_busy(bfqq))
+ bfqq->bfqd->wr_busy_queues--;
+ bfqq->wr_coeff = 1;
+ bfqq->wr_cur_max_time = 0;
+ bfqq->last_wr_start_finish = jiffies;
+ /*
+ * Trigger a weight change on the next invocation of
+ * __bfq_entity_update_weight_prio.
+ */
+ bfqq->entity.prio_changed = 1;
+}
+
+void bfq_end_wr_async_queues(struct bfq_data *bfqd,
+ struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ if (bfqg->async_bfqq[i][j])
+ bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
+ if (bfqg->async_idle_bfqq)
+ bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
+}
+
+static void bfq_end_wr(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+
+ spin_lock_irq(&bfqd->lock);
+
+ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
+ bfq_bfqq_end_wr(bfqq);
+ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
+ bfq_bfqq_end_wr(bfqq);
+ bfq_end_wr_async(bfqd);
+
+ spin_unlock_irq(&bfqd->lock);
+}
+
+static sector_t bfq_io_struct_pos(void *io_struct, bool request)
+{
+ if (request)
+ return blk_rq_pos(io_struct);
+ else
+ return ((struct bio *)io_struct)->bi_iter.bi_sector;
+}
+
+static int bfq_rq_close_to_sector(void *io_struct, bool request,
+ sector_t sector)
+{
+ return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
+ BFQQ_CLOSE_THR;
+}
+
+static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ sector_t sector)
+{
+ struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
+ struct rb_node *parent, *node;
+ struct bfq_queue *__bfqq;
+
+ if (RB_EMPTY_ROOT(root))
+ return NULL;
+
+ /*
+ * First, if we find a request starting at the end of the last
+ * request, choose it.
+ */
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
+ if (__bfqq)
+ return __bfqq;
+
+ /*
+ * If the exact sector wasn't found, the parent of the NULL leaf
+ * will contain the closest sector (rq_pos_tree sorted by
+ * next_request position).
+ */
+ __bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
+ return __bfqq;
+
+ if (blk_rq_pos(__bfqq->next_rq) < sector)
+ node = rb_next(&__bfqq->pos_node);
+ else
+ node = rb_prev(&__bfqq->pos_node);
+ if (!node)
+ return NULL;
+
+ __bfqq = rb_entry(node, struct bfq_queue, pos_node);
+ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
+ return __bfqq;
+
+ return NULL;
+}
+
+static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
+ struct bfq_queue *cur_bfqq,
+ sector_t sector)
+{
+ struct bfq_queue *bfqq;
+
+ /*
+ * We shall notice if some of the queues are cooperating,
+ * e.g., working closely on the same area of the device. In
+ * that case, we can group them together and: 1) don't waste
+ * time idling, and 2) serve the union of their requests in
+ * the best possible order for throughput.
+ */
+ bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
+ if (!bfqq || bfqq == cur_bfqq)
+ return NULL;
+
+ return bfqq;
+}
+
+static struct bfq_queue *
+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+{
+ int process_refs, new_process_refs;
+ struct bfq_queue *__bfqq;
+
+ /*
+ * If there are no process references on the new_bfqq, then it is
+ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
+ * may have dropped their last reference (not just their last process
+ * reference).
+ */
+ if (!bfqq_process_refs(new_bfqq))
+ return NULL;
+
+ /* Avoid a circular list and skip interim queue merges. */
+ while ((__bfqq = new_bfqq->new_bfqq)) {
+ if (__bfqq == bfqq)
+ return NULL;
+ new_bfqq = __bfqq;
+ }
+
+ process_refs = bfqq_process_refs(bfqq);
+ new_process_refs = bfqq_process_refs(new_bfqq);
+ /*
+ * If the process for the bfqq has gone away, there is no
+ * sense in merging the queues.
+ */
+ if (process_refs == 0 || new_process_refs == 0)
+ return NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
+ new_bfqq->pid);
+
+ /*
+ * Merging is just a redirection: the requests of the process
+ * owning one of the two queues are redirected to the other queue.
+ * The latter queue, in its turn, is set as shared if this is the
+ * first time that the requests of some process are redirected to
+ * it.
+ *
+ * We redirect bfqq to new_bfqq and not the opposite, because
+ * we are in the context of the process owning bfqq, thus we
+ * have the io_cq of this process. So we can immediately
+ * configure this io_cq to redirect the requests of the
+ * process to new_bfqq. In contrast, the io_cq of new_bfqq is
+ * not available any more (new_bfqq->bic == NULL).
+ *
+ * Anyway, even in case new_bfqq coincides with the in-service
+ * queue, redirecting requests the in-service queue is the
+ * best option, as we feed the in-service queue with new
+ * requests close to the last request served and, by doing so,
+ * are likely to increase the throughput.
+ */
+ bfqq->new_bfqq = new_bfqq;
+ new_bfqq->ref += process_refs;
+ return new_bfqq;
+}
+
+static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
+ struct bfq_queue *new_bfqq)
+{
+ if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
+ (bfqq->ioprio_class != new_bfqq->ioprio_class))
+ return false;
+
+ /*
+ * If either of the queues has already been detected as seeky,
+ * then merging it with the other queue is unlikely to lead to
+ * sequential I/O.
+ */
+ if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
+ return false;
+
+ /*
+ * Interleaved I/O is known to be done by (some) applications
+ * only for reads, so it does not make sense to merge async
+ * queues.
+ */
+ if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
+ return false;
+
+ return true;
+}
+
+/*
+ * If this function returns true, then bfqq cannot be merged. The idea
+ * is that true cooperation happens very early after processes start
+ * to do I/O. Usually, late cooperations are just accidental false
+ * positives. In case bfqq is weight-raised, such false positives
+ * would evidently degrade latency guarantees for bfqq.
+ */
+static bool wr_from_too_long(struct bfq_queue *bfqq)
+{
+ return bfqq->wr_coeff > 1 &&
+ time_is_before_jiffies(bfqq->last_wr_start_finish +
+ msecs_to_jiffies(100));
+}
+
+/*
+ * Attempt to schedule a merge of bfqq with the currently in-service
+ * queue or with a close queue among the scheduled queues. Return
+ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
+ * structure otherwise.
+ *
+ * The OOM queue is not allowed to participate to cooperation: in fact, since
+ * the requests temporarily redirected to the OOM queue could be redirected
+ * again to dedicated queues at any time, the state needed to correctly
+ * handle merging with the OOM queue would be quite complex and expensive
+ * to maintain. Besides, in such a critical condition as an out of memory,
+ * the benefits of queue merging may be little relevant, or even negligible.
+ *
+ * Weight-raised queues can be merged only if their weight-raising
+ * period has just started. In fact cooperating processes are usually
+ * started together. Thus, with this filter we avoid false positives
+ * that would jeopardize low-latency guarantees.
+ *
+ * WARNING: queue merging may impair fairness among non-weight raised
+ * queues, for at least two reasons: 1) the original weight of a
+ * merged queue may change during the merged state, 2) even being the
+ * weight the same, a merged queue may be bloated with many more
+ * requests than the ones produced by its originally-associated
+ * process.
+ */
+static struct bfq_queue *
+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ void *io_struct, bool request)
+{
+ struct bfq_queue *in_service_bfqq, *new_bfqq;
+
+ if (bfqq->new_bfqq)
+ return bfqq->new_bfqq;
+
+ if (!io_struct ||
+ wr_from_too_long(bfqq) ||
+ unlikely(bfqq == &bfqd->oom_bfqq))
+ return NULL;
+
+ /* If there is only one backlogged queue, don't search. */
+ if (bfqd->busy_queues == 1)
+ return NULL;
+
+ in_service_bfqq = bfqd->in_service_queue;
+
+ if (!in_service_bfqq || in_service_bfqq == bfqq
+ || wr_from_too_long(in_service_bfqq) ||
+ unlikely(in_service_bfqq == &bfqd->oom_bfqq))
+ goto check_scheduled;
+
+ if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
+ bfqq->entity.parent == in_service_bfqq->entity.parent &&
+ bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
+ new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
+ if (new_bfqq)
+ return new_bfqq;
+ }
+ /*
+ * Check whether there is a cooperator among currently scheduled
+ * queues. The only thing we need is that the bio/request is not
+ * NULL, as we need it to establish whether a cooperator exists.
+ */
+check_scheduled:
+ new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
+ bfq_io_struct_pos(io_struct, request));
+
+ if (new_bfqq && !wr_from_too_long(new_bfqq) &&
+ likely(new_bfqq != &bfqd->oom_bfqq) &&
+ bfq_may_be_close_cooperator(bfqq, new_bfqq))
+ return bfq_setup_merge(bfqq, new_bfqq);
+
+ return NULL;
+}
+
+static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
+{
+ struct bfq_io_cq *bic = bfqq->bic;
+
+ /*
+ * If !bfqq->bic, the queue is already shared or its requests
+ * have already been redirected to a shared queue; both idle window
+ * and weight raising state have already been saved. Do nothing.
+ */
+ if (!bic)
+ return;
+
+ bic->saved_ttime = bfqq->ttime;
+ bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
+ bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
+ bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
+ bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
+ bic->saved_wr_coeff = bfqq->wr_coeff;
+ bic->saved_wr_start_at_switch_to_srt = bfqq->wr_start_at_switch_to_srt;
+ bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
+ bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
+}
+
+static void
+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
+ struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+{
+ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
+ (unsigned long)new_bfqq->pid);
+ /* Save weight raising and idle window of the merged queues */
+ bfq_bfqq_save_state(bfqq);
+ bfq_bfqq_save_state(new_bfqq);
+ if (bfq_bfqq_IO_bound(bfqq))
+ bfq_mark_bfqq_IO_bound(new_bfqq);
+ bfq_clear_bfqq_IO_bound(bfqq);
+
+ /*
+ * If bfqq is weight-raised, then let new_bfqq inherit
+ * weight-raising. To reduce false positives, neglect the case
+ * where bfqq has just been created, but has not yet made it
+ * to be weight-raised (which may happen because EQM may merge
+ * bfqq even before bfq_add_request is executed for the first
+ * time for bfqq). Handling this case would however be very
+ * easy, thanks to the flag just_created.
+ */
+ if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
+ new_bfqq->wr_coeff = bfqq->wr_coeff;
+ new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
+ new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
+ new_bfqq->wr_start_at_switch_to_srt =
+ bfqq->wr_start_at_switch_to_srt;
+ if (bfq_bfqq_busy(new_bfqq))
+ bfqd->wr_busy_queues++;
+ new_bfqq->entity.prio_changed = 1;
+ }
+
+ if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
+ bfqq->wr_coeff = 1;
+ bfqq->entity.prio_changed = 1;
+ if (bfq_bfqq_busy(bfqq))
+ bfqd->wr_busy_queues--;
+ }
+
+ bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
+ bfqd->wr_busy_queues);
+
+ /*
+ * Merge queues (that is, let bic redirect its requests to new_bfqq)
+ */
+ bic_set_bfqq(bic, new_bfqq, 1);
+ bfq_mark_bfqq_coop(new_bfqq);
+ /*
+ * new_bfqq now belongs to at least two bics (it is a shared queue):
+ * set new_bfqq->bic to NULL. bfqq either:
+ * - does not belong to any bic any more, and hence bfqq->bic must
+ * be set to NULL, or
+ * - is a queue whose owning bics have already been redirected to a
+ * different queue, hence the queue is destined to not belong to
+ * any bic soon and bfqq->bic is already NULL (therefore the next
+ * assignment causes no harm).
+ */
+ new_bfqq->bic = NULL;
+ bfqq->bic = NULL;
+ /* release process reference to bfqq */
+ bfq_put_queue(bfqq);
+}
+
+static bool bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ bool is_sync = op_is_sync(bio->bi_opf);
+ struct bfq_queue *bfqq = bfqd->bio_bfqq, *new_bfqq;
+
+ /*
+ * Disallow merge of a sync bio into an async request.
+ */
+ if (is_sync && !rq_is_sync(rq))
+ return false;
+
+ /*
+ * Lookup the bfqq that this bio will be queued with. Allow
+ * merge only if rq is queued there.
+ */
+ if (!bfqq)
+ return false;
+
+ /*
+ * We take advantage of this function to perform an early merge
+ * of the queues of possible cooperating processes.
+ */
+ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
+ if (new_bfqq) {
+ /*
+ * bic still points to bfqq, then it has not yet been
+ * redirected to some other bfq_queue, and a queue
+ * merge beween bfqq and new_bfqq can be safely
+ * fulfillled, i.e., bic can be redirected to new_bfqq
+ * and bfqq can be put.
+ */
+ bfq_merge_bfqqs(bfqd, bfqd->bio_bic, bfqq,
+ new_bfqq);
+ /*
+ * If we get here, bio will be queued into new_queue,
+ * so use new_bfqq to decide whether bio and rq can be
+ * merged.
+ */
+ bfqq = new_bfqq;
+
+ /*
+ * Change also bqfd->bio_bfqq, as
+ * bfqd->bio_bic now points to new_bfqq, and
+ * this function may be invoked again (and then may
+ * use again bqfd->bio_bfqq).
+ */
+ bfqd->bio_bfqq = bfqq;
+ }
+
+ return bfqq == RQ_BFQQ(rq);
+}
+
+/*
+ * Set the maximum time for the in-service queue to consume its
+ * budget. This prevents seeky processes from lowering the throughput.
+ * In practice, a time-slice service scheme is used with seeky
+ * processes.
+ */
+static void bfq_set_budget_timeout(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ unsigned int timeout_coeff;
+
+ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
+ timeout_coeff = 1;
+ else
+ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
+
+ bfqd->last_budget_start = ktime_get();
+
+ bfqq->budget_timeout = jiffies +
+ bfqd->bfq_timeout * timeout_coeff;
+}
+
+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ if (bfqq) {
+ bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
+ bfq_clear_bfqq_fifo_expire(bfqq);
+
+ bfqd->budgets_assigned = (bfqd->budgets_assigned * 7 + 256) / 8;
+
+ if (time_is_before_jiffies(bfqq->last_wr_start_finish) &&
+ bfqq->wr_coeff > 1 &&
+ bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
+ time_is_before_jiffies(bfqq->budget_timeout)) {
+ /*
+ * For soft real-time queues, move the start
+ * of the weight-raising period forward by the
+ * time the queue has not received any
+ * service. Otherwise, a relatively long
+ * service delay is likely to cause the
+ * weight-raising period of the queue to end,
+ * because of the short duration of the
+ * weight-raising period of a soft real-time
+ * queue. It is worth noting that this move
+ * is not so dangerous for the other queues,
+ * because soft real-time queues are not
+ * greedy.
+ *
+ * To not add a further variable, we use the
+ * overloaded field budget_timeout to
+ * determine for how long the queue has not
+ * received service, i.e., how much time has
+ * elapsed since the queue expired. However,
+ * this is a little imprecise, because
+ * budget_timeout is set to jiffies if bfqq
+ * not only expires, but also remains with no
+ * request.
+ */
+ if (time_after(bfqq->budget_timeout,
+ bfqq->last_wr_start_finish))
+ bfqq->last_wr_start_finish +=
+ jiffies - bfqq->budget_timeout;
+ else
+ bfqq->last_wr_start_finish = jiffies;
+ }
+
+ bfq_set_budget_timeout(bfqd, bfqq);
+ bfq_log_bfqq(bfqd, bfqq,
+ "set_in_service_queue, cur-budget = %d",
+ bfqq->entity.budget);
+ }
+
+ bfqd->in_service_queue = bfqq;
+}
+
+/*
+ * Get and set a new queue for service.
+ */
+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
+
+ __bfq_set_in_service_queue(bfqd, bfqq);
+ return bfqq;
+}
+
+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->in_service_queue;
+ u32 sl;
+
+ bfq_mark_bfqq_wait_request(bfqq);
+
+ /*
+ * We don't want to idle for seeks, but we do want to allow
+ * fair distribution of slice time for a process doing back-to-back
+ * seeks. So allow a little bit of time for him to submit a new rq.
+ */
+ sl = bfqd->bfq_slice_idle;
+ /*
+ * Unless the queue is being weight-raised or the scenario is
+ * asymmetric, grant only minimum idle time if the queue
+ * is seeky. A long idling is preserved for a weight-raised
+ * queue, or, more in general, in an asymmetric scenario,
+ * because a long idling is needed for guaranteeing to a queue
+ * its reserved share of the throughput (in particular, it is
+ * needed if the queue has a higher weight than some other
+ * queue).
+ */
+ if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
+ bfq_symmetric_scenario(bfqd))
+ sl = min_t(u64, sl, BFQ_MIN_TT);
+
+ bfqd->last_idling_start = ktime_get();
+ hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl),
+ HRTIMER_MODE_REL);
+ bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
+}
+
+/*
+ * In autotuning mode, max_budget is dynamically recomputed as the
+ * amount of sectors transferred in timeout at the estimated peak
+ * rate. This enables BFQ to utilize a full timeslice with a full
+ * budget, even if the in-service queue is served at peak rate. And
+ * this maximises throughput with sequential workloads.
+ */
+static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
+{
+ return (u64)bfqd->peak_rate * USEC_PER_MSEC *
+ jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT;
+}
+
+/*
+ * Update parameters related to throughput and responsiveness, as a
+ * function of the estimated peak rate. See comments on
+ * bfq_calc_max_budget(), and on T_slow and T_fast arrays.
+ */
+static void update_thr_responsiveness_params(struct bfq_data *bfqd)
+{
+ int dev_type = blk_queue_nonrot(bfqd->queue);
+
+ if (bfqd->bfq_user_max_budget == 0)
+ bfqd->bfq_max_budget =
+ bfq_calc_max_budget(bfqd);
+
+ if (bfqd->device_speed == BFQ_BFQD_FAST &&
+ bfqd->peak_rate < device_speed_thresh[dev_type]) {
+ bfqd->device_speed = BFQ_BFQD_SLOW;
+ bfqd->RT_prod = R_slow[dev_type] *
+ T_slow[dev_type];
+ } else if (bfqd->device_speed == BFQ_BFQD_SLOW &&
+ bfqd->peak_rate > device_speed_thresh[dev_type]) {
+ bfqd->device_speed = BFQ_BFQD_FAST;
+ bfqd->RT_prod = R_fast[dev_type] *
+ T_fast[dev_type];
+ }
+
+ bfq_log(bfqd,
+"dev_type %s dev_speed_class = %s (%llu sects/sec), thresh %llu setcs/sec",
+ dev_type == 0 ? "ROT" : "NONROT",
+ bfqd->device_speed == BFQ_BFQD_FAST ? "FAST" : "SLOW",
+ bfqd->device_speed == BFQ_BFQD_FAST ?
+ (USEC_PER_SEC*(u64)R_fast[dev_type])>>BFQ_RATE_SHIFT :
+ (USEC_PER_SEC*(u64)R_slow[dev_type])>>BFQ_RATE_SHIFT,
+ (USEC_PER_SEC*(u64)device_speed_thresh[dev_type])>>
+ BFQ_RATE_SHIFT);
+}
+
+static void bfq_reset_rate_computation(struct bfq_data *bfqd,
+ struct request *rq)
+{
+ if (rq != NULL) { /* new rq dispatch now, reset accordingly */
+ bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns();
+ bfqd->peak_rate_samples = 1;
+ bfqd->sequential_samples = 0;
+ bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size =
+ blk_rq_sectors(rq);
+ } else /* no new rq dispatched, just reset the number of samples */
+ bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
+
+ bfq_log(bfqd,
+ "reset_rate_computation at end, sample %u/%u tot_sects %llu",
+ bfqd->peak_rate_samples, bfqd->sequential_samples,
+ bfqd->tot_sectors_dispatched);
+}
+
+static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
+{
+ u32 rate, weight, divisor;
+
+ /*
+ * For the convergence property to hold (see comments on
+ * bfq_update_peak_rate()) and for the assessment to be
+ * reliable, a minimum number of samples must be present, and
+ * a minimum amount of time must have elapsed. If not so, do
+ * not compute new rate. Just reset parameters, to get ready
+ * for a new evaluation attempt.
+ */
+ if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
+ bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL)
+ goto reset_computation;
+
+ /*
+ * If a new request completion has occurred after last
+ * dispatch, then, to approximate the rate at which requests
+ * have been served by the device, it is more precise to
+ * extend the observation interval to the last completion.
+ */
+ bfqd->delta_from_first =
+ max_t(u64, bfqd->delta_from_first,
+ bfqd->last_completion - bfqd->first_dispatch);
+
+ /*
+ * Rate computed in sects/usec, and not sects/nsec, for
+ * precision issues.
+ */
+ rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT,
+ div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
+
+ /*
+ * Peak rate not updated if:
+ * - the percentage of sequential dispatches is below 3/4 of the
+ * total, and rate is below the current estimated peak rate
+ * - rate is unreasonably high (> 20M sectors/sec)
+ */
+ if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 &&
+ rate <= bfqd->peak_rate) ||
+ rate > 20<<BFQ_RATE_SHIFT)
+ goto reset_computation;
+
+ /*
+ * We have to update the peak rate, at last! To this purpose,
+ * we use a low-pass filter. We compute the smoothing constant
+ * of the filter as a function of the 'weight' of the new
+ * measured rate.
+ *
+ * As can be seen in next formulas, we define this weight as a
+ * quantity proportional to how sequential the workload is,
+ * and to how long the observation time interval is.
+ *
+ * The weight runs from 0 to 8. The maximum value of the
+ * weight, 8, yields the minimum value for the smoothing
+ * constant. At this minimum value for the smoothing constant,
+ * the measured rate contributes for half of the next value of
+ * the estimated peak rate.
+ *
+ * So, the first step is to compute the weight as a function
+ * of how sequential the workload is. Note that the weight
+ * cannot reach 9, because bfqd->sequential_samples cannot
+ * become equal to bfqd->peak_rate_samples, which, in its
+ * turn, holds true because bfqd->sequential_samples is not
+ * incremented for the first sample.
+ */
+ weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples;
+
+ /*
+ * Second step: further refine the weight as a function of the
+ * duration of the observation interval.
+ */
+ weight = min_t(u32, 8,
+ div_u64(weight * bfqd->delta_from_first,
+ BFQ_RATE_REF_INTERVAL));
+
+ /*
+ * Divisor ranging from 10, for minimum weight, to 2, for
+ * maximum weight.
+ */
+ divisor = 10 - weight;
+
+ /*
+ * Finally, update peak rate:
+ *
+ * peak_rate = peak_rate * (divisor-1) / divisor + rate / divisor
+ */
+ bfqd->peak_rate *= divisor-1;
+ bfqd->peak_rate /= divisor;
+ rate /= divisor; /* smoothing constant alpha = 1/divisor */
+
+ bfqd->peak_rate += rate;
+ update_thr_responsiveness_params(bfqd);
+
+reset_computation:
+ bfq_reset_rate_computation(bfqd, rq);
+}
+
+/*
+ * Update the read/write peak rate (the main quantity used for
+ * auto-tuning, see update_thr_responsiveness_params()).
+ *
+ * It is not trivial to estimate the peak rate (correctly): because of
+ * the presence of sw and hw queues between the scheduler and the
+ * device components that finally serve I/O requests, it is hard to
+ * say exactly when a given dispatched request is served inside the
+ * device, and for how long. As a consequence, it is hard to know
+ * precisely at what rate a given set of requests is actually served
+ * by the device.
+ *
+ * On the opposite end, the dispatch time of any request is trivially
+ * available, and, from this piece of information, the "dispatch rate"
+ * of requests can be immediately computed. So, the idea in the next
+ * function is to use what is known, namely request dispatch times
+ * (plus, when useful, request completion times), to estimate what is
+ * unknown, namely in-device request service rate.
+ *
+ * The main issue is that, because of the above facts, the rate at
+ * which a certain set of requests is dispatched over a certain time
+ * interval can vary greatly with respect to the rate at which the
+ * same requests are then served. But, since the size of any
+ * intermediate queue is limited, and the service scheme is lossless
+ * (no request is silently dropped), the following obvious convergence
+ * property holds: the number of requests dispatched MUST become
+ * closer and closer to the number of requests completed as the
+ * observation interval grows. This is the key property used in
+ * the next function to estimate the peak service rate as a function
+ * of the observed dispatch rate. The function assumes to be invoked
+ * on every request dispatch.
+ */
+static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
+{
+ u64 now_ns = ktime_get_ns();
+
+ if (bfqd->peak_rate_samples == 0) { /* first dispatch */
+ bfq_log(bfqd, "update_peak_rate: goto reset, samples %d",
+ bfqd->peak_rate_samples);
+ bfq_reset_rate_computation(bfqd, rq);
+ goto update_last_values; /* will add one sample */
+ }
+
+ /*
+ * Device idle for very long: the observation interval lasting
+ * up to this dispatch cannot be a valid observation interval
+ * for computing a new peak rate (similarly to the late-
+ * completion event in bfq_completed_request()). Go to
+ * update_rate_and_reset to have the following three steps
+ * taken:
+ * - close the observation interval at the last (previous)
+ * request dispatch or completion
+ * - compute rate, if possible, for that observation interval
+ * - start a new observation interval with this dispatch
+ */
+ if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
+ bfqd->rq_in_driver == 0)
+ goto update_rate_and_reset;
+
+ /* Update sampling information */
+ bfqd->peak_rate_samples++;
+
+ if ((bfqd->rq_in_driver > 0 ||
+ now_ns - bfqd->last_completion < BFQ_MIN_TT)
+ && get_sdist(bfqd->last_position, rq) < BFQQ_SEEK_THR)
+ bfqd->sequential_samples++;
+
+ bfqd->tot_sectors_dispatched += blk_rq_sectors(rq);
+
+ /* Reset max observed rq size every 32 dispatches */
+ if (likely(bfqd->peak_rate_samples % 32))
+ bfqd->last_rq_max_size =
+ max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size);
+ else
+ bfqd->last_rq_max_size = blk_rq_sectors(rq);
+
+ bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
+
+ /* Target observation interval not yet reached, go on sampling */
+ if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL)
+ goto update_last_values;
+
+update_rate_and_reset:
+ bfq_update_rate_reset(bfqd, rq);
+update_last_values:
+ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
+ bfqd->last_dispatch = now_ns;
+}
+
+/*
+ * Remove request from internal lists.
+ */
+static void bfq_dispatch_remove(struct request_queue *q, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ /*
+ * For consistency, the next instruction should have been
+ * executed after removing the request from the queue and
+ * dispatching it. We execute instead this instruction before
+ * bfq_remove_request() (and hence introduce a temporary
+ * inconsistency), for efficiency. In fact, should this
+ * dispatch occur for a non in-service bfqq, this anticipated
+ * increment prevents two counters related to bfqq->dispatched
+ * from risking to be, first, uselessly decremented, and then
+ * incremented again when the (new) value of bfqq->dispatched
+ * happens to be taken into account.
+ */
+ bfqq->dispatched++;
+ bfq_update_peak_rate(q->elevator->elevator_data, rq);
+
+ bfq_remove_request(q, rq);
+}
+
+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ /*
+ * If this bfqq is shared between multiple processes, check
+ * to make sure that those processes are still issuing I/Os
+ * within the mean seek distance. If not, it may be time to
+ * break the queues apart again.
+ */
+ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
+ bfq_mark_bfqq_split_coop(bfqq);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ if (bfqq->dispatched == 0)
+ /*
+ * Overloading budget_timeout field to store
+ * the time at which the queue remains with no
+ * backlog and no outstanding request; used by
+ * the weight-raising mechanism.
+ */
+ bfqq->budget_timeout = jiffies;
+
+ bfq_del_bfqq_busy(bfqd, bfqq, true);
+ } else {
+ bfq_requeue_bfqq(bfqd, bfqq);
+ /*
+ * Resort priority tree of potential close cooperators.
+ */
+ bfq_pos_tree_add_move(bfqd, bfqq);
+ }
+
+ /*
+ * All in-service entities must have been properly deactivated
+ * or requeued before executing the next function, which
+ * resets all in-service entites as no more in service.
+ */
+ __bfq_bfqd_reset_in_service(bfqd);
+}
+
+/**
+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
+ * @bfqd: device data.
+ * @bfqq: queue to update.
+ * @reason: reason for expiration.
+ *
+ * Handle the feedback on @bfqq budget at queue expiration.
+ * See the body for detailed comments.
+ */
+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ enum bfqq_expiration reason)
+{
+ struct request *next_rq;
+ int budget, min_budget;
+
+ min_budget = bfq_min_budget(bfqd);
+
+ if (bfqq->wr_coeff == 1)
+ budget = bfqq->max_budget;
+ else /*
+ * Use a constant, low budget for weight-raised queues,
+ * to help achieve a low latency. Keep it slightly higher
+ * than the minimum possible budget, to cause a little
+ * bit fewer expirations.
+ */
+ budget = 2 * min_budget;
+
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
+ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
+ budget, bfq_min_budget(bfqd));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
+ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
+
+ if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
+ switch (reason) {
+ /*
+ * Caveat: in all the following cases we trade latency
+ * for throughput.
+ */
+ case BFQQE_TOO_IDLE:
+ /*
+ * This is the only case where we may reduce
+ * the budget: if there is no request of the
+ * process still waiting for completion, then
+ * we assume (tentatively) that the timer has
+ * expired because the batch of requests of
+ * the process could have been served with a
+ * smaller budget. Hence, betting that
+ * process will behave in the same way when it
+ * becomes backlogged again, we reduce its
+ * next budget. As long as we guess right,
+ * this budget cut reduces the latency
+ * experienced by the process.
+ *
+ * However, if there are still outstanding
+ * requests, then the process may have not yet
+ * issued its next request just because it is
+ * still waiting for the completion of some of
+ * the still outstanding ones. So in this
+ * subcase we do not reduce its budget, on the
+ * contrary we increase it to possibly boost
+ * the throughput, as discussed in the
+ * comments to the BUDGET_TIMEOUT case.
+ */
+ if (bfqq->dispatched > 0) /* still outstanding reqs */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ else {
+ if (budget > 5 * min_budget)
+ budget -= 4 * min_budget;
+ else
+ budget = min_budget;
+ }
+ break;
+ case BFQQE_BUDGET_TIMEOUT:
+ /*
+ * We double the budget here because it gives
+ * the chance to boost the throughput if this
+ * is not a seeky process (and has bumped into
+ * this timeout because of, e.g., ZBR).
+ */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ break;
+ case BFQQE_BUDGET_EXHAUSTED:
+ /*
+ * The process still has backlog, and did not
+ * let either the budget timeout or the disk
+ * idling timeout expire. Hence it is not
+ * seeky, has a short thinktime and may be
+ * happy with a higher budget too. So
+ * definitely increase the budget of this good
+ * candidate to boost the disk throughput.
+ */
+ budget = min(budget * 4, bfqd->bfq_max_budget);
+ break;
+ case BFQQE_NO_MORE_REQUESTS:
+ /*
+ * For queues that expire for this reason, it
+ * is particularly important to keep the
+ * budget close to the actual service they
+ * need. Doing so reduces the timestamp
+ * misalignment problem described in the
+ * comments in the body of
+ * __bfq_activate_entity. In fact, suppose
+ * that a queue systematically expires for
+ * BFQQE_NO_MORE_REQUESTS and presents a
+ * new request in time to enjoy timestamp
+ * back-shifting. The larger the budget of the
+ * queue is with respect to the service the
+ * queue actually requests in each service
+ * slot, the more times the queue can be
+ * reactivated with the same virtual finish
+ * time. It follows that, even if this finish
+ * time is pushed to the system virtual time
+ * to reduce the consequent timestamp
+ * misalignment, the queue unjustly enjoys for
+ * many re-activations a lower finish time
+ * than all newly activated queues.
+ *
+ * The service needed by bfqq is measured
+ * quite precisely by bfqq->entity.service.
+ * Since bfqq does not enjoy device idling,
+ * bfqq->entity.service is equal to the number
+ * of sectors that the process associated with
+ * bfqq requested to read/write before waiting
+ * for request completions, or blocking for
+ * other reasons.
+ */
+ budget = max_t(int, bfqq->entity.service, min_budget);
+ break;
+ default:
+ return;
+ }
+ } else if (!bfq_bfqq_sync(bfqq)) {
+ /*
+ * Async queues get always the maximum possible
+ * budget, as for them we do not care about latency
+ * (in addition, their ability to dispatch is limited
+ * by the charging factor).
+ */
+ budget = bfqd->bfq_max_budget;
+ }
+
+ bfqq->max_budget = budget;
+
+ if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
+ !bfqd->bfq_user_max_budget)
+ bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
+
+ /*
+ * If there is still backlog, then assign a new budget, making
+ * sure that it is large enough for the next request. Since
+ * the finish time of bfqq must be kept in sync with the
+ * budget, be sure to call __bfq_bfqq_expire() *after* this
+ * update.
+ *
+ * If there is no backlog, then no need to update the budget;
+ * it will be updated on the arrival of a new request.
+ */
+ next_rq = bfqq->next_rq;
+ if (next_rq)
+ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+
+ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
+ next_rq ? blk_rq_sectors(next_rq) : 0,
+ bfqq->entity.budget);
+}
+
+/*
+ * Return true if the process associated with bfqq is "slow". The slow
+ * flag is used, in addition to the budget timeout, to reduce the
+ * amount of service provided to seeky processes, and thus reduce
+ * their chances to lower the throughput. More details in the comments
+ * on the function bfq_bfqq_expire().
+ *
+ * An important observation is in order: as discussed in the comments
+ * on the function bfq_update_peak_rate(), with devices with internal
+ * queues, it is hard if ever possible to know when and for how long
+ * an I/O request is processed by the device (apart from the trivial
+ * I/O pattern where a new request is dispatched only after the
+ * previous one has been completed). This makes it hard to evaluate
+ * the real rate at which the I/O requests of each bfq_queue are
+ * served. In fact, for an I/O scheduler like BFQ, serving a
+ * bfq_queue means just dispatching its requests during its service
+ * slot (i.e., until the budget of the queue is exhausted, or the
+ * queue remains idle, or, finally, a timeout fires). But, during the
+ * service slot of a bfq_queue, around 100 ms at most, the device may
+ * be even still processing requests of bfq_queues served in previous
+ * service slots. On the opposite end, the requests of the in-service
+ * bfq_queue may be completed after the service slot of the queue
+ * finishes.
+ *
+ * Anyway, unless more sophisticated solutions are used
+ * (where possible), the sum of the sizes of the requests dispatched
+ * during the service slot of a bfq_queue is probably the only
+ * approximation available for the service received by the bfq_queue
+ * during its service slot. And this sum is the quantity used in this
+ * function to evaluate the I/O speed of a process.
+ */
+static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool compensate, enum bfqq_expiration reason,
+ unsigned long *delta_ms)
+{
+ ktime_t delta_ktime;
+ u32 delta_usecs;
+ bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
+
+ if (!bfq_bfqq_sync(bfqq))
+ return false;
+
+ if (compensate)
+ delta_ktime = bfqd->last_idling_start;
+ else
+ delta_ktime = ktime_get();
+ delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
+ delta_usecs = ktime_to_us(delta_ktime);
+
+ /* don't use too short time intervals */
+ if (delta_usecs < 1000) {
+ if (blk_queue_nonrot(bfqd->queue))
+ /*
+ * give same worst-case guarantees as idling
+ * for seeky
+ */
+ *delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC;
+ else /* charge at least one seek */
+ *delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
+
+ return slow;
+ }
+
+ *delta_ms = delta_usecs / USEC_PER_MSEC;
+
+ /*
+ * Use only long (> 20ms) intervals to filter out excessive
+ * spikes in service rate estimation.
+ */
+ if (delta_usecs > 20000) {
+ /*
+ * Caveat for rotational devices: processes doing I/O
+ * in the slower disk zones tend to be slow(er) even
+ * if not seeky. In this respect, the estimated peak
+ * rate is likely to be an average over the disk
+ * surface. Accordingly, to not be too harsh with
+ * unlucky processes, a process is deemed slow only if
+ * its rate has been lower than half of the estimated
+ * peak rate.
+ */
+ slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow);
+
+ return slow;
+}
+
+/*
+ * To be deemed as soft real-time, an application must meet two
+ * requirements. First, the application must not require an average
+ * bandwidth higher than the approximate bandwidth required to playback or
+ * record a compressed high-definition video.
+ * The next function is invoked on the completion of the last request of a
+ * batch, to compute the next-start time instant, soft_rt_next_start, such
+ * that, if the next request of the application does not arrive before
+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
+ *
+ * The second requirement is that the request pattern of the application is
+ * isochronous, i.e., that, after issuing a request or a batch of requests,
+ * the application stops issuing new requests until all its pending requests
+ * have been completed. After that, the application may issue a new batch,
+ * and so on.
+ * For this reason the next function is invoked to compute
+ * soft_rt_next_start only for applications that meet this requirement,
+ * whereas soft_rt_next_start is set to infinity for applications that do
+ * not.
+ *
+ * Unfortunately, even a greedy application may happen to behave in an
+ * isochronous way if the CPU load is high. In fact, the application may
+ * stop issuing requests while the CPUs are busy serving other processes,
+ * then restart, then stop again for a while, and so on. In addition, if
+ * the disk achieves a low enough throughput with the request pattern
+ * issued by the application (e.g., because the request pattern is random
+ * and/or the device is slow), then the application may meet the above
+ * bandwidth requirement too. To prevent such a greedy application to be
+ * deemed as soft real-time, a further rule is used in the computation of
+ * soft_rt_next_start: soft_rt_next_start must be higher than the current
+ * time plus the maximum time for which the arrival of a request is waited
+ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
+ * This filters out greedy applications, as the latter issue instead their
+ * next request as soon as possible after the last one has been completed
+ * (in contrast, when a batch of requests is completed, a soft real-time
+ * application spends some time processing data).
+ *
+ * Unfortunately, the last filter may easily generate false positives if
+ * only bfqd->bfq_slice_idle is used as a reference time interval and one
+ * or both the following cases occur:
+ * 1) HZ is so low that the duration of a jiffy is comparable to or higher
+ * than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
+ * HZ=100.
+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
+ * for a while, then suddenly 'jump' by several units to recover the lost
+ * increments. This seems to happen, e.g., inside virtual machines.
+ * To address this issue, we do not use as a reference time interval just
+ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
+ * particular we add the minimum number of jiffies for which the filter
+ * seems to be quite precise also in embedded systems and KVM/QEMU virtual
+ * machines.
+ */
+static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ return max(bfqq->last_idle_bklogged +
+ HZ * bfqq->service_from_backlogged /
+ bfqd->bfq_wr_max_softrt_rate,
+ jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
+}
+
+/*
+ * Return the farthest future time instant according to jiffies
+ * macros.
+ */
+static unsigned long bfq_greatest_from_now(void)
+{
+ return jiffies + MAX_JIFFY_OFFSET;
+}
+
+/*
+ * Return the farthest past time instant according to jiffies
+ * macros.
+ */
+static unsigned long bfq_smallest_from_now(void)
+{
+ return jiffies - MAX_JIFFY_OFFSET;
+}
+
+/**
+ * bfq_bfqq_expire - expire a queue.
+ * @bfqd: device owning the queue.
+ * @bfqq: the queue to expire.
+ * @compensate: if true, compensate for the time spent idling.
+ * @reason: the reason causing the expiration.
+ *
+ * If the process associated with bfqq does slow I/O (e.g., because it
+ * issues random requests), we charge bfqq with the time it has been
+ * in service instead of the service it has received (see
+ * bfq_bfqq_charge_time for details on how this goal is achieved). As
+ * a consequence, bfqq will typically get higher timestamps upon
+ * reactivation, and hence it will be rescheduled as if it had
+ * received more service than what it has actually received. In the
+ * end, bfqq receives less service in proportion to how slowly its
+ * associated process consumes its budgets (and hence how seriously it
+ * tends to lower the throughput). In addition, this time-charging
+ * strategy guarantees time fairness among slow processes. In
+ * contrast, if the process associated with bfqq is not slow, we
+ * charge bfqq exactly with the service it has received.
+ *
+ * Charging time to the first type of queues and the exact service to
+ * the other has the effect of using the WF2Q+ policy to schedule the
+ * former on a timeslice basis, without violating service domain
+ * guarantees among the latter.
+ */
+void bfq_bfqq_expire(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ bool compensate,
+ enum bfqq_expiration reason)
+{
+ bool slow;
+ unsigned long delta = 0;
+ struct bfq_entity *entity = &bfqq->entity;
+ int ref;
+
+ /*
+ * Check whether the process is slow (see bfq_bfqq_is_slow).
+ */
+ slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
+
+ /*
+ * Increase service_from_backlogged before next statement,
+ * because the possible next invocation of
+ * bfq_bfqq_charge_time would likely inflate
+ * entity->service. In contrast, service_from_backlogged must
+ * contain real service, to enable the soft real-time
+ * heuristic to correctly compute the bandwidth consumed by
+ * bfqq.
+ */
+ bfqq->service_from_backlogged += entity->service;
+
+ /*
+ * As above explained, charge slow (typically seeky) and
+ * timed-out queues with the time and not the service
+ * received, to favor sequential workloads.
+ *
+ * Processes doing I/O in the slower disk zones will tend to
+ * be slow(er) even if not seeky. Therefore, since the
+ * estimated peak rate is actually an average over the disk
+ * surface, these processes may timeout just for bad luck. To
+ * avoid punishing them, do not charge time to processes that
+ * succeeded in consuming at least 2/3 of their budget. This
+ * allows BFQ to preserve enough elasticity to still perform
+ * bandwidth, and not time, distribution with little unlucky
+ * or quasi-sequential processes.
+ */
+ if (bfqq->wr_coeff == 1 &&
+ (slow ||
+ (reason == BFQQE_BUDGET_TIMEOUT &&
+ bfq_bfqq_budget_left(bfqq) >= entity->budget / 3)))
+ bfq_bfqq_charge_time(bfqd, bfqq, delta);
+
+ if (reason == BFQQE_TOO_IDLE &&
+ entity->service <= 2 * entity->budget / 10)
+ bfq_clear_bfqq_IO_bound(bfqq);
+
+ if (bfqd->low_latency && bfqq->wr_coeff == 1)
+ bfqq->last_wr_start_finish = jiffies;
+
+ if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
+ RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ /*
+ * If we get here, and there are no outstanding
+ * requests, then the request pattern is isochronous
+ * (see the comments on the function
+ * bfq_bfqq_softrt_next_start()). Thus we can compute
+ * soft_rt_next_start. If, instead, the queue still
+ * has outstanding requests, then we have to wait for
+ * the completion of all the outstanding requests to
+ * discover whether the request pattern is actually
+ * isochronous.
+ */
+ if (bfqq->dispatched == 0)
+ bfqq->soft_rt_next_start =
+ bfq_bfqq_softrt_next_start(bfqd, bfqq);
+ else {
+ /*
+ * The application is still waiting for the
+ * completion of one or more requests:
+ * prevent it from possibly being incorrectly
+ * deemed as soft real-time by setting its
+ * soft_rt_next_start to infinity. In fact,
+ * without this assignment, the application
+ * would be incorrectly deemed as soft
+ * real-time if:
+ * 1) it issued a new request before the
+ * completion of all its in-flight
+ * requests, and
+ * 2) at that time, its soft_rt_next_start
+ * happened to be in the past.
+ */
+ bfqq->soft_rt_next_start =
+ bfq_greatest_from_now();
+ /*
+ * Schedule an update of soft_rt_next_start to when
+ * the task may be discovered to be isochronous.
+ */
+ bfq_mark_bfqq_softrt_update(bfqq);
+ }
+ }
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "expire (%d, slow %d, num_disp %d, idle_win %d)", reason,
+ slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq));
+
+ /*
+ * Increase, decrease or leave budget unchanged according to
+ * reason.
+ */
+ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
+ ref = bfqq->ref;
+ __bfq_bfqq_expire(bfqd, bfqq);
+
+ /* mark bfqq as waiting a request only if a bic still points to it */
+ if (ref > 1 && !bfq_bfqq_busy(bfqq) &&
+ reason != BFQQE_BUDGET_TIMEOUT &&
+ reason != BFQQE_BUDGET_EXHAUSTED)
+ bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
+}
+
+/*
+ * Budget timeout is not implemented through a dedicated timer, but
+ * just checked on request arrivals and completions, as well as on
+ * idle timer expirations.
+ */
+static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
+{
+ return time_is_before_eq_jiffies(bfqq->budget_timeout);
+}
+
+/*
+ * If we expire a queue that is actively waiting (i.e., with the
+ * device idled) for the arrival of a new request, then we may incur
+ * the timestamp misalignment problem described in the body of the
+ * function __bfq_activate_entity. Hence we return true only if this
+ * condition does not hold, or if the queue is slow enough to deserve
+ * only to be kicked off for preserving a high throughput.
+ */
+static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "may_budget_timeout: wait_request %d left %d timeout %d",
+ bfq_bfqq_wait_request(bfqq),
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3,
+ bfq_bfqq_budget_timeout(bfqq));
+
+ return (!bfq_bfqq_wait_request(bfqq) ||
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)
+ &&
+ bfq_bfqq_budget_timeout(bfqq);
+}
+
+/*
+ * For a queue that becomes empty, device idling is allowed only if
+ * this function returns true for the queue. As a consequence, since
+ * device idling plays a critical role in both throughput boosting and
+ * service guarantees, the return value of this function plays a
+ * critical role in both these aspects as well.
+ *
+ * In a nutshell, this function returns true only if idling is
+ * beneficial for throughput or, even if detrimental for throughput,
+ * idling is however necessary to preserve service guarantees (low
+ * latency, desired throughput distribution, ...). In particular, on
+ * NCQ-capable devices, this function tries to return false, so as to
+ * help keep the drives' internal queues full, whenever this helps the
+ * device boost the throughput without causing any service-guarantee
+ * issue.
+ *
+ * In more detail, the return value of this function is obtained by,
+ * first, computing a number of boolean variables that take into
+ * account throughput and service-guarantee issues, and, then,
+ * combining these variables in a logical expression. Most of the
+ * issues taken into account are not trivial. We discuss these issues
+ * individually while introducing the variables.
+ */
+static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+ bool idling_boosts_thr, idling_boosts_thr_without_issues,
+ idling_needed_for_service_guarantees,
+ asymmetric_scenario;
+
+ if (bfqd->strict_guarantees)
+ return true;
+
+ /*
+ * The next variable takes into account the cases where idling
+ * boosts the throughput.
+ *
+ * The value of the variable is computed considering, first, that
+ * idling is virtually always beneficial for the throughput if:
+ * (a) the device is not NCQ-capable, or
+ * (b) regardless of the presence of NCQ, the device is rotational
+ * and the request pattern for bfqq is I/O-bound and sequential.
+ *
+ * Secondly, and in contrast to the above item (b), idling an
+ * NCQ-capable flash-based device would not boost the
+ * throughput even with sequential I/O; rather it would lower
+ * the throughput in proportion to how fast the device
+ * is. Accordingly, the next variable is true if any of the
+ * above conditions (a) and (b) is true, and, in particular,
+ * happens to be false if bfqd is an NCQ-capable flash-based
+ * device.
+ */
+ idling_boosts_thr = !bfqd->hw_tag ||
+ (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
+ bfq_bfqq_idle_window(bfqq));
+
+ /*
+ * The value of the next variable,
+ * idling_boosts_thr_without_issues, is equal to that of
+ * idling_boosts_thr, unless a special case holds. In this
+ * special case, described below, idling may cause problems to
+ * weight-raised queues.
+ *
+ * When the request pool is saturated (e.g., in the presence
+ * of write hogs), if the processes associated with
+ * non-weight-raised queues ask for requests at a lower rate,
+ * then processes associated with weight-raised queues have a
+ * higher probability to get a request from the pool
+ * immediately (or at least soon) when they need one. Thus
+ * they have a higher probability to actually get a fraction
+ * of the device throughput proportional to their high
+ * weight. This is especially true with NCQ-capable drives,
+ * which enqueue several requests in advance, and further
+ * reorder internally-queued requests.
+ *
+ * For this reason, we force to false the value of
+ * idling_boosts_thr_without_issues if there are weight-raised
+ * busy queues. In this case, and if bfqq is not weight-raised,
+ * this guarantees that the device is not idled for bfqq (if,
+ * instead, bfqq is weight-raised, then idling will be
+ * guaranteed by another variable, see below). Combined with
+ * the timestamping rules of BFQ (see [1] for details), this
+ * behavior causes bfqq, and hence any sync non-weight-raised
+ * queue, to get a lower number of requests served, and thus
+ * to ask for a lower number of requests from the request
+ * pool, before the busy weight-raised queues get served
+ * again. This often mitigates starvation problems in the
+ * presence of heavy write workloads and NCQ, thereby
+ * guaranteeing a higher application and system responsiveness
+ * in these hostile scenarios.
+ */
+ idling_boosts_thr_without_issues = idling_boosts_thr &&
+ bfqd->wr_busy_queues == 0;
+
+ /*
+ * There is then a case where idling must be performed not
+ * for throughput concerns, but to preserve service
+ * guarantees.
+ *
+ * To introduce this case, we can note that allowing the drive
+ * to enqueue more than one request at a time, and hence
+ * delegating de facto final scheduling decisions to the
+ * drive's internal scheduler, entails loss of control on the
+ * actual request service order. In particular, the critical
+ * situation is when requests from different processes happen
+ * to be present, at the same time, in the internal queue(s)
+ * of the drive. In such a situation, the drive, by deciding
+ * the service order of the internally-queued requests, does
+ * determine also the actual throughput distribution among
+ * these processes. But the drive typically has no notion or
+ * concern about per-process throughput distribution, and
+ * makes its decisions only on a per-request basis. Therefore,
+ * the service distribution enforced by the drive's internal
+ * scheduler is likely to coincide with the desired
+ * device-throughput distribution only in a completely
+ * symmetric scenario where:
+ * (i) each of these processes must get the same throughput as
+ * the others;
+ * (ii) all these processes have the same I/O pattern
+ (either sequential or random).
+ * In fact, in such a scenario, the drive will tend to treat
+ * the requests of each of these processes in about the same
+ * way as the requests of the others, and thus to provide
+ * each of these processes with about the same throughput
+ * (which is exactly the desired throughput distribution). In
+ * contrast, in any asymmetric scenario, device idling is
+ * certainly needed to guarantee that bfqq receives its
+ * assigned fraction of the device throughput (see [1] for
+ * details).
+ *
+ * We address this issue by controlling, actually, only the
+ * symmetry sub-condition (i), i.e., provided that
+ * sub-condition (i) holds, idling is not performed,
+ * regardless of whether sub-condition (ii) holds. In other
+ * words, only if sub-condition (i) holds, then idling is
+ * allowed, and the device tends to be prevented from queueing
+ * many requests, possibly of several processes. The reason
+ * for not controlling also sub-condition (ii) is that we
+ * exploit preemption to preserve guarantees in case of
+ * symmetric scenarios, even if (ii) does not hold, as
+ * explained in the next two paragraphs.
+ *
+ * Even if a queue, say Q, is expired when it remains idle, Q
+ * can still preempt the new in-service queue if the next
+ * request of Q arrives soon (see the comments on
+ * bfq_bfqq_update_budg_for_activation). If all queues and
+ * groups have the same weight, this form of preemption,
+ * combined with the hole-recovery heuristic described in the
+ * comments on function bfq_bfqq_update_budg_for_activation,
+ * are enough to preserve a correct bandwidth distribution in
+ * the mid term, even without idling. In fact, even if not
+ * idling allows the internal queues of the device to contain
+ * many requests, and thus to reorder requests, we can rather
+ * safely assume that the internal scheduler still preserves a
+ * minimum of mid-term fairness. The motivation for using
+ * preemption instead of idling is that, by not idling,
+ * service guarantees are preserved without minimally
+ * sacrificing throughput. In other words, both a high
+ * throughput and its desired distribution are obtained.
+ *
+ * More precisely, this preemption-based, idleless approach
+ * provides fairness in terms of IOPS, and not sectors per
+ * second. This can be seen with a simple example. Suppose
+ * that there are two queues with the same weight, but that
+ * the first queue receives requests of 8 sectors, while the
+ * second queue receives requests of 1024 sectors. In
+ * addition, suppose that each of the two queues contains at
+ * most one request at a time, which implies that each queue
+ * always remains idle after it is served. Finally, after
+ * remaining idle, each queue receives very quickly a new
+ * request. It follows that the two queues are served
+ * alternatively, preempting each other if needed. This
+ * implies that, although both queues have the same weight,
+ * the queue with large requests receives a service that is
+ * 1024/8 times as high as the service received by the other
+ * queue.
+ *
+ * On the other hand, device idling is performed, and thus
+ * pure sector-domain guarantees are provided, for the
+ * following queues, which are likely to need stronger
+ * throughput guarantees: weight-raised queues, and queues
+ * with a higher weight than other queues. When such queues
+ * are active, sub-condition (i) is false, which triggers
+ * device idling.
+ *
+ * According to the above considerations, the next variable is
+ * true (only) if sub-condition (i) holds. To compute the
+ * value of this variable, we not only use the return value of
+ * the function bfq_symmetric_scenario(), but also check
+ * whether bfqq is being weight-raised, because
+ * bfq_symmetric_scenario() does not take into account also
+ * weight-raised queues (see comments on
+ * bfq_weights_tree_add()).
+ *
+ * As a side note, it is worth considering that the above
+ * device-idling countermeasures may however fail in the
+ * following unlucky scenario: if idling is (correctly)
+ * disabled in a time period during which all symmetry
+ * sub-conditions hold, and hence the device is allowed to
+ * enqueue many requests, but at some later point in time some
+ * sub-condition stops to hold, then it may become impossible
+ * to let requests be served in the desired order until all
+ * the requests already queued in the device have been served.
+ */
+ asymmetric_scenario = bfqq->wr_coeff > 1 ||
+ !bfq_symmetric_scenario(bfqd);
+
+ /*
+ * Finally, there is a case where maximizing throughput is the
+ * best choice even if it may cause unfairness toward
+ * bfqq. Such a case is when bfqq became active in a burst of
+ * queue activations. Queues that became active during a large
+ * burst benefit only from throughput, as discussed in the
+ * comments on bfq_handle_burst. Thus, if bfqq became active
+ * in a burst and not idling the device maximizes throughput,
+ * then the device must no be idled, because not idling the
+ * device provides bfqq and all other queues in the burst with
+ * maximum benefit. Combining this and the above case, we can
+ * now establish when idling is actually needed to preserve
+ * service guarantees.
+ */
+ idling_needed_for_service_guarantees =
+ asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq);
+
+ /*
+ * We have now all the components we need to compute the return
+ * value of the function, which is true only if both the following
+ * conditions hold:
+ * 1) bfqq is sync, because idling make sense only for sync queues;
+ * 2) idling either boosts the throughput (without issues), or
+ * is necessary to preserve service guarantees.
+ */
+ return bfq_bfqq_sync(bfqq) &&
+ (idling_boosts_thr_without_issues ||
+ idling_needed_for_service_guarantees);
+}
+
+/*
+ * If the in-service queue is empty but the function bfq_bfqq_may_idle
+ * returns true, then:
+ * 1) the queue must remain in service and cannot be expired, and
+ * 2) the device must be idled to wait for the possible arrival of a new
+ * request for the queue.
+ * See the comments on the function bfq_bfqq_may_idle for the reasons
+ * why performing device idling is the best choice to boost the throughput
+ * and preserve service guarantees when bfq_bfqq_may_idle itself
+ * returns true.
+ */
+static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 &&
+ bfq_bfqq_may_idle(bfqq);
+}
+
+/*
+ * Select a queue for service. If we have a current queue in service,
+ * check whether to continue servicing it, or retrieve and set a new one.
+ */
+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+ struct request *next_rq;
+ enum bfqq_expiration reason = BFQQE_BUDGET_TIMEOUT;
+
+ bfqq = bfqd->in_service_queue;
+ if (!bfqq)
+ goto new_queue;
+
+ bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
+
+ if (bfq_may_expire_for_budg_timeout(bfqq) &&
+ !bfq_bfqq_wait_request(bfqq) &&
+ !bfq_bfqq_must_idle(bfqq))
+ goto expire;
+
+check_queue:
+ /*
+ * This loop is rarely executed more than once. Even when it
+ * happens, it is much more convenient to re-execute this loop
+ * than to return NULL and trigger a new dispatch to get a
+ * request served.
+ */
+ next_rq = bfqq->next_rq;
+ /*
+ * If bfqq has requests queued and it has enough budget left to
+ * serve them, keep the queue, otherwise expire it.
+ */
+ if (next_rq) {
+ if (bfq_serv_to_charge(next_rq, bfqq) >
+ bfq_bfqq_budget_left(bfqq)) {
+ /*
+ * Expire the queue for budget exhaustion,
+ * which makes sure that the next budget is
+ * enough to serve the next request, even if
+ * it comes from the fifo expired path.
+ */
+ reason = BFQQE_BUDGET_EXHAUSTED;
+ goto expire;
+ } else {
+ /*
+ * The idle timer may be pending because we may
+ * not disable disk idling even when a new request
+ * arrives.
+ */
+ if (bfq_bfqq_wait_request(bfqq)) {
+ /*
+ * If we get here: 1) at least a new request
+ * has arrived but we have not disabled the
+ * timer because the request was too small,
+ * 2) then the block layer has unplugged
+ * the device, causing the dispatch to be
+ * invoked.
+ *
+ * Since the device is unplugged, now the
+ * requests are probably large enough to
+ * provide a reasonable throughput.
+ * So we disable idling.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
+ bfqg_stats_update_idle_time(bfqq_group(bfqq));
+ }
+ goto keep_queue;
+ }
+ }
+
+ /*
+ * No requests pending. However, if the in-service queue is idling
+ * for a new request, or has requests waiting for a completion and
+ * may idle after their completion, then keep it anyway.
+ */
+ if (bfq_bfqq_wait_request(bfqq) ||
+ (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {
+ bfqq = NULL;
+ goto keep_queue;
+ }
+
+ reason = BFQQE_NO_MORE_REQUESTS;
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, false, reason);
+new_queue:
+ bfqq = bfq_set_in_service_queue(bfqd);
+ if (bfqq) {
+ bfq_log_bfqq(bfqd, bfqq, "select_queue: checking new queue");
+ goto check_queue;
+ }
+keep_queue:
+ if (bfqq)
+ bfq_log_bfqq(bfqd, bfqq, "select_queue: returned this queue");
+ else
+ bfq_log(bfqd, "select_queue: no queue returned");
+
+ return bfqq;
+}
+
+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
+ bfq_log_bfqq(bfqd, bfqq,
+ "raising period dur %u/%u msec, old coeff %u, w %d(%d)",
+ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time),
+ bfqq->wr_coeff,
+ bfqq->entity.weight, bfqq->entity.orig_weight);
+
+ if (entity->prio_changed)
+ bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
+
+ /*
+ * If the queue was activated in a burst, or too much
+ * time has elapsed from the beginning of this
+ * weight-raising period, then end weight raising.
+ */
+ if (bfq_bfqq_in_large_burst(bfqq))
+ bfq_bfqq_end_wr(bfqq);
+ else if (time_is_before_jiffies(bfqq->last_wr_start_finish +
+ bfqq->wr_cur_max_time)) {
+ if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time ||
+ time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt +
+ bfq_wr_duration(bfqd)))
+ bfq_bfqq_end_wr(bfqq);
+ else {
+ /* switch back to interactive wr */
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ bfqq->last_wr_start_finish =
+ bfqq->wr_start_at_switch_to_srt;
+ bfqq->entity.prio_changed = 1;
+ }
+ }
+ }
+ /* Update weight both if it must be raised and if it must be lowered */
+ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
+ __bfq_entity_update_weight_prio(
+ bfq_entity_service_tree(entity),
+ entity);
+}
+
+/*
+ * Dispatch next request from bfqq.
+ */
+static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct request *rq = bfqq->next_rq;
+ unsigned long service_to_charge;
+
+ service_to_charge = bfq_serv_to_charge(rq, bfqq);
+
+ bfq_bfqq_served(bfqq, service_to_charge);
+
+ bfq_dispatch_remove(bfqd->queue, rq);
+
+ /*
+ * If weight raising has to terminate for bfqq, then next
+ * function causes an immediate update of bfqq's weight,
+ * without waiting for next activation. As a consequence, on
+ * expiration, bfqq will be timestamped as if has never been
+ * weight-raised during this service slot, even if it has
+ * received part or even most of the service as a
+ * weight-raised queue. This inflates bfqq's timestamps, which
+ * is beneficial, as bfqq is then more willing to leave the
+ * device immediately to possible other weight-raised queues.
+ */
+ bfq_update_wr_data(bfqd, bfqq);
+
+ /*
+ * Expire bfqq, pretending that its budget expired, if bfqq
+ * belongs to CLASS_IDLE and other queues are waiting for
+ * service.
+ */
+ if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
+ goto expire;
+
+ return rq;
+
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, false, BFQQE_BUDGET_EXHAUSTED);
+ return rq;
+}
+
+static bool bfq_has_work(struct blk_mq_hw_ctx *hctx)
+{
+ struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
+
+ /*
+ * Avoiding lock: a race on bfqd->busy_queues should cause at
+ * most a call to dispatch for nothing
+ */
+ return !list_empty_careful(&bfqd->dispatch) ||
+ bfqd->busy_queues > 0;
+}
+
+static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
+{
+ struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
+ struct request *rq = NULL;
+ struct bfq_queue *bfqq = NULL;
+
+ if (!list_empty(&bfqd->dispatch)) {
+ rq = list_first_entry(&bfqd->dispatch, struct request,
+ queuelist);
+ list_del_init(&rq->queuelist);
+
+ bfqq = RQ_BFQQ(rq);
+
+ if (bfqq) {
+ /*
+ * Increment counters here, because this
+ * dispatch does not follow the standard
+ * dispatch flow (where counters are
+ * incremented)
+ */
+ bfqq->dispatched++;
+
+ goto inc_in_driver_start_rq;
+ }
+
+ /*
+ * We exploit the put_rq_private hook to decrement
+ * rq_in_driver, but put_rq_private will not be
+ * invoked on this request. So, to avoid unbalance,
+ * just start this request, without incrementing
+ * rq_in_driver. As a negative consequence,
+ * rq_in_driver is deceptively lower than it should be
+ * while this request is in service. This may cause
+ * bfq_schedule_dispatch to be invoked uselessly.
+ *
+ * As for implementing an exact solution, the
+ * put_request hook, if defined, is probably invoked
+ * also on this request. So, by exploiting this hook,
+ * we could 1) increment rq_in_driver here, and 2)
+ * decrement it in put_request. Such a solution would
+ * let the value of the counter be always accurate,
+ * but it would entail using an extra interface
+ * function. This cost seems higher than the benefit,
+ * being the frequency of non-elevator-private
+ * requests very low.
+ */
+ goto start_rq;
+ }
+
+ bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
+
+ if (bfqd->busy_queues == 0)
+ goto exit;
+
+ /*
+ * Force device to serve one request at a time if
+ * strict_guarantees is true. Forcing this service scheme is
+ * currently the ONLY way to guarantee that the request
+ * service order enforced by the scheduler is respected by a
+ * queueing device. Otherwise the device is free even to make
+ * some unlucky request wait for as long as the device
+ * wishes.
+ *
+ * Of course, serving one request at at time may cause loss of
+ * throughput.
+ */
+ if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
+ goto exit;
+
+ bfqq = bfq_select_queue(bfqd);
+ if (!bfqq)
+ goto exit;
+
+ rq = bfq_dispatch_rq_from_bfqq(bfqd, bfqq);
+
+ if (rq) {
+inc_in_driver_start_rq:
+ bfqd->rq_in_driver++;
+start_rq:
+ rq->rq_flags |= RQF_STARTED;
+ }
+exit:
+ return rq;
+}
+
+static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
+{
+ struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
+ struct request *rq;
+
+ spin_lock_irq(&bfqd->lock);
+
+ rq = __bfq_dispatch_request(hctx);
+ spin_unlock_irq(&bfqd->lock);
+
+ return rq;
+}
+
+/*
+ * Task holds one reference to the queue, dropped when task exits. Each rq
+ * in-flight on this queue also holds a reference, dropped when rq is freed.
+ *
+ * Scheduler lock must be held here. Recall not to use bfqq after calling
+ * this function on it.
+ */
+void bfq_put_queue(struct bfq_queue *bfqq)
+{
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_group *bfqg = bfqq_group(bfqq);
+#endif
+
+ if (bfqq->bfqd)
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d",
+ bfqq, bfqq->ref);
+
+ bfqq->ref--;
+ if (bfqq->ref)
+ return;
+
+ if (bfq_bfqq_sync(bfqq))
+ /*
+ * The fact that this queue is being destroyed does not
+ * invalidate the fact that this queue may have been
+ * activated during the current burst. As a consequence,
+ * although the queue does not exist anymore, and hence
+ * needs to be removed from the burst list if there,
+ * the burst size has not to be decremented.
+ */
+ hlist_del_init(&bfqq->burst_list_node);
+
+ kmem_cache_free(bfq_pool, bfqq);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ bfqg_put(bfqg);
+#endif
+}
+
+static void bfq_put_cooperator(struct bfq_queue *bfqq)
+{
+ struct bfq_queue *__bfqq, *next;
+
+ /*
+ * If this queue was scheduled to merge with another queue, be
+ * sure to drop the reference taken on that queue (and others in
+ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
+ */
+ __bfqq = bfqq->new_bfqq;
+ while (__bfqq) {
+ if (__bfqq == bfqq)
+ break;
+ next = __bfqq->new_bfqq;
+ bfq_put_queue(__bfqq);
+ __bfqq = next;
+ }
+}
+
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ if (bfqq == bfqd->in_service_queue) {
+ __bfq_bfqq_expire(bfqd, bfqq);
+ bfq_schedule_dispatch(bfqd);
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq); /* release process reference */
+}
+
+static void bfq_exit_icq_bfqq(struct bfq_io_cq *bic, bool is_sync)
+{
+ struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync);
+ struct bfq_data *bfqd;
+
+ if (bfqq)
+ bfqd = bfqq->bfqd; /* NULL if scheduler already exited */
+
+ if (bfqq && bfqd) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&bfqd->lock, flags);
+ bfq_exit_bfqq(bfqd, bfqq);
+ bic_set_bfqq(bic, NULL, is_sync);
+ spin_unlock_irqrestore(&bfqd->lock, flags);
+ }
+}
+
+static void bfq_exit_icq(struct io_cq *icq)
+{
+ struct bfq_io_cq *bic = icq_to_bic(icq);
+
+ bfq_exit_icq_bfqq(bic, true);
+ bfq_exit_icq_bfqq(bic, false);
+}
+
+/*
+ * Update the entity prio values; note that the new values will not
+ * be used until the next (re)activation.
+ */
+static void
+bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
+{
+ struct task_struct *tsk = current;
+ int ioprio_class;
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ if (!bfqd)
+ return;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
+ switch (ioprio_class) {
+ default:
+ dev_err(bfqq->bfqd->queue->backing_dev_info->dev,
+ "bfq: bad prio class %d\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * No prio set, inherit CPU scheduling settings.
+ */
+ bfqq->new_ioprio = task_nice_ioprio(tsk);
+ bfqq->new_ioprio_class = task_nice_ioclass(tsk);
+ break;
+ case IOPRIO_CLASS_RT:
+ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
+ bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
+ break;
+ case IOPRIO_CLASS_BE:
+ bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
+ bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
+ break;
+ case IOPRIO_CLASS_IDLE:
+ bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
+ bfqq->new_ioprio = 7;
+ bfq_clear_bfqq_idle_window(bfqq);
+ break;
+ }
+
+ if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
+ pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
+ bfqq->new_ioprio);
+ bfqq->new_ioprio = IOPRIO_BE_NR;
+ }
+
+ bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
+ bfqq->entity.prio_changed = 1;
+}
+
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bio *bio, bool is_sync,
+ struct bfq_io_cq *bic);
+
+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
+{
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+ struct bfq_queue *bfqq;
+ int ioprio = bic->icq.ioc->ioprio;
+
+ /*
+ * This condition may trigger on a newly created bic, be sure to
+ * drop the lock before returning.
+ */
+ if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
+ return;
+
+ bic->ioprio = ioprio;
+
+ bfqq = bic_to_bfqq(bic, false);
+ if (bfqq) {
+ /* release process reference on this queue */
+ bfq_put_queue(bfqq);
+ bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
+ bic_set_bfqq(bic, bfqq, false);
+ }
+
+ bfqq = bic_to_bfqq(bic, true);
+ if (bfqq)
+ bfq_set_next_ioprio_data(bfqq, bic);
+}
+
+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_io_cq *bic, pid_t pid, int is_sync)
+{
+ RB_CLEAR_NODE(&bfqq->entity.rb_node);
+ INIT_LIST_HEAD(&bfqq->fifo);
+ INIT_HLIST_NODE(&bfqq->burst_list_node);
+
+ bfqq->ref = 0;
+ bfqq->bfqd = bfqd;
+
+ if (bic)
+ bfq_set_next_ioprio_data(bfqq, bic);
+
+ if (is_sync) {
+ if (!bfq_class_idle(bfqq))
+ bfq_mark_bfqq_idle_window(bfqq);
+ bfq_mark_bfqq_sync(bfqq);
+ bfq_mark_bfqq_just_created(bfqq);
+ } else
+ bfq_clear_bfqq_sync(bfqq);
+
+ /* set end request to minus infinity from now */
+ bfqq->ttime.last_end_request = ktime_get_ns() + 1;
+
+ bfq_mark_bfqq_IO_bound(bfqq);
+
+ bfqq->pid = pid;
+
+ /* Tentative initial value to trade off between thr and lat */
+ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
+ bfqq->budget_timeout = bfq_smallest_from_now();
+
+ bfqq->wr_coeff = 1;
+ bfqq->last_wr_start_finish = jiffies;
+ bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now();
+ bfqq->split_time = bfq_smallest_from_now();
+
+ /*
+ * Set to the value for which bfqq will not be deemed as
+ * soft rt when it becomes backlogged.
+ */
+ bfqq->soft_rt_next_start = bfq_greatest_from_now();
+
+ /* first request is almost certainly seeky */
+ bfqq->seek_history = 1;
+}
+
+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int ioprio_class, int ioprio)
+{
+ switch (ioprio_class) {
+ case IOPRIO_CLASS_RT:
+ return &bfqg->async_bfqq[0][ioprio];
+ case IOPRIO_CLASS_NONE:
+ ioprio = IOPRIO_NORM;
+ /* fall through */
+ case IOPRIO_CLASS_BE:
+ return &bfqg->async_bfqq[1][ioprio];
+ case IOPRIO_CLASS_IDLE:
+ return &bfqg->async_idle_bfqq;
+ default:
+ return NULL;
+ }
+}
+
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bio *bio, bool is_sync,
+ struct bfq_io_cq *bic)
+{
+ const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
+ const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
+ struct bfq_queue **async_bfqq = NULL;
+ struct bfq_queue *bfqq;
+ struct bfq_group *bfqg;
+
+ rcu_read_lock();
+
+ bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
+ if (!bfqg) {
+ bfqq = &bfqd->oom_bfqq;
+ goto out;
+ }
+
+ if (!is_sync) {
+ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
+ ioprio);
+ bfqq = *async_bfqq;
+ if (bfqq)
+ goto out;
+ }
+
+ bfqq = kmem_cache_alloc_node(bfq_pool,
+ GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
+ bfqd->queue->node);
+
+ if (bfqq) {
+ bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
+ is_sync);
+ bfq_init_entity(&bfqq->entity, bfqg);
+ bfq_log_bfqq(bfqd, bfqq, "allocated");
+ } else {
+ bfqq = &bfqd->oom_bfqq;
+ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
+ goto out;
+ }
+
+ /*
+ * Pin the queue now that it's allocated, scheduler exit will
+ * prune it.
+ */
+ if (async_bfqq) {
+ bfqq->ref++; /*
+ * Extra group reference, w.r.t. sync
+ * queue. This extra reference is removed
+ * only if bfqq->bfqg disappears, to
+ * guarantee that this queue is not freed
+ * until its group goes away.
+ */
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
+ bfqq, bfqq->ref);
+ *async_bfqq = bfqq;
+ }
+
+out:
+ bfqq->ref++; /* get a process reference to this queue */
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
+ rcu_read_unlock();
+ return bfqq;
+}
+
+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_ttime *ttime = &bfqq->ttime;
+ u64 elapsed = ktime_get_ns() - bfqq->ttime.last_end_request;
+
+ elapsed = min_t(u64, elapsed, 2ULL * bfqd->bfq_slice_idle);
+
+ ttime->ttime_samples = (7*bfqq->ttime.ttime_samples + 256) / 8;
+ ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed, 8);
+ ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
+ ttime->ttime_samples);
+}
+
+static void
+bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ bfqq->seek_history <<= 1;
+ bfqq->seek_history |=
+ get_sdist(bfqq->last_request_pos, rq) > BFQQ_SEEK_THR &&
+ (!blk_queue_nonrot(bfqd->queue) ||
+ blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT);
+}
+
+/*
+ * Disable idle window if the process thinks too long or seeks so much that
+ * it doesn't matter.
+ */
+static void bfq_update_idle_window(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct bfq_io_cq *bic)
+{
+ int enable_idle;
+
+ /* Don't idle for async or idle io prio class. */
+ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
+ return;
+
+ /* Idle window just restored, statistics are meaningless. */
+ if (time_is_after_eq_jiffies(bfqq->split_time +
+ bfqd->bfq_wr_min_idle_time))
+ return;
+
+ enable_idle = bfq_bfqq_idle_window(bfqq);
+
+ if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
+ bfqd->bfq_slice_idle == 0 ||
+ (bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
+ bfqq->wr_coeff == 1))
+ enable_idle = 0;
+ else if (bfq_sample_valid(bfqq->ttime.ttime_samples)) {
+ if (bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle &&
+ bfqq->wr_coeff == 1)
+ enable_idle = 0;
+ else
+ enable_idle = 1;
+ }
+ bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
+ enable_idle);
+
+ if (enable_idle)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+}
+
+/*
+ * Called when a new fs request (rq) is added to bfqq. Check if there's
+ * something we should do about it.
+ */
+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ struct bfq_io_cq *bic = RQ_BIC(rq);
+
+ if (rq->cmd_flags & REQ_META)
+ bfqq->meta_pending++;
+
+ bfq_update_io_thinktime(bfqd, bfqq);
+ bfq_update_io_seektime(bfqd, bfqq, rq);
+ if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
+ !BFQQ_SEEKY(bfqq))
+ bfq_update_idle_window(bfqd, bfqq, bic);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "rq_enqueued: idle_window=%d (seeky %d)",
+ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq));
+
+ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
+
+ if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
+ bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
+ blk_rq_sectors(rq) < 32;
+ bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
+
+ /*
+ * There is just this request queued: if the request
+ * is small and the queue is not to be expired, then
+ * just exit.
+ *
+ * In this way, if the device is being idled to wait
+ * for a new request from the in-service queue, we
+ * avoid unplugging the device and committing the
+ * device to serve just a small request. On the
+ * contrary, we wait for the block layer to decide
+ * when to unplug the device: hopefully, new requests
+ * will be merged to this one quickly, then the device
+ * will be unplugged and larger requests will be
+ * dispatched.
+ */
+ if (small_req && !budget_timeout)
+ return;
+
+ /*
+ * A large enough request arrived, or the queue is to
+ * be expired: in both cases disk idling is to be
+ * stopped, so clear wait_request flag and reset
+ * timer.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
+ bfqg_stats_update_idle_time(bfqq_group(bfqq));
+
+ /*
+ * The queue is not empty, because a new request just
+ * arrived. Hence we can safely expire the queue, in
+ * case of budget timeout, without risking that the
+ * timestamps of the queue are not updated correctly.
+ * See [1] for more details.
+ */
+ if (budget_timeout)
+ bfq_bfqq_expire(bfqd, bfqq, false,
+ BFQQE_BUDGET_TIMEOUT);
+ }
+}
+
+static void __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq),
+ *new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
+
+ if (new_bfqq) {
+ if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
+ new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
+ /*
+ * Release the request's reference to the old bfqq
+ * and make sure one is taken to the shared queue.
+ */
+ new_bfqq->allocated++;
+ bfqq->allocated--;
+ new_bfqq->ref++;
+ bfq_clear_bfqq_just_created(bfqq);
+ /*
+ * If the bic associated with the process
+ * issuing this request still points to bfqq
+ * (and thus has not been already redirected
+ * to new_bfqq or even some other bfq_queue),
+ * then complete the merge and redirect it to
+ * new_bfqq.
+ */
+ if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
+ bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
+ bfqq, new_bfqq);
+ /*
+ * rq is about to be enqueued into new_bfqq,
+ * release rq reference on bfqq
+ */
+ bfq_put_queue(bfqq);
+ rq->elv.priv[1] = new_bfqq;
+ bfqq = new_bfqq;
+ }
+
+ bfq_add_request(rq);
+
+ rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
+ list_add_tail(&rq->queuelist, &bfqq->fifo);
+
+ bfq_rq_enqueued(bfqd, bfqq, rq);
+}
+
+static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
+ bool at_head)
+{
+ struct request_queue *q = hctx->queue;
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ spin_lock_irq(&bfqd->lock);
+ if (blk_mq_sched_try_insert_merge(q, rq)) {
+ spin_unlock_irq(&bfqd->lock);
+ return;
+ }
+
+ spin_unlock_irq(&bfqd->lock);
+
+ blk_mq_sched_request_inserted(rq);
+
+ spin_lock_irq(&bfqd->lock);
+ if (at_head || blk_rq_is_passthrough(rq)) {
+ if (at_head)
+ list_add(&rq->queuelist, &bfqd->dispatch);
+ else
+ list_add_tail(&rq->queuelist, &bfqd->dispatch);
+ } else {
+ __bfq_insert_request(bfqd, rq);
+
+ if (rq_mergeable(rq)) {
+ elv_rqhash_add(q, rq);
+ if (!q->last_merge)
+ q->last_merge = rq;
+ }
+ }
+
+ spin_unlock_irq(&bfqd->lock);
+}
+
+static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
+ struct list_head *list, bool at_head)
+{
+ while (!list_empty(list)) {
+ struct request *rq;
+
+ rq = list_first_entry(list, struct request, queuelist);
+ list_del_init(&rq->queuelist);
+ bfq_insert_request(hctx, rq, at_head);
+ }
+}
+
+static void bfq_update_hw_tag(struct bfq_data *bfqd)
+{
+ bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
+ bfqd->rq_in_driver);
+
+ if (bfqd->hw_tag == 1)
+ return;
+
+ /*
+ * This sample is valid if the number of outstanding requests
+ * is large enough to allow a queueing behavior. Note that the
+ * sum is not exact, as it's not taking into account deactivated
+ * requests.
+ */
+ if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
+ return;
+
+ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
+ return;
+
+ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
+ bfqd->max_rq_in_driver = 0;
+ bfqd->hw_tag_samples = 0;
+}
+
+static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd)
+{
+ u64 now_ns;
+ u32 delta_us;
+
+ bfq_update_hw_tag(bfqd);
+
+ bfqd->rq_in_driver--;
+ bfqq->dispatched--;
+
+ if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
+ /*
+ * Set budget_timeout (which we overload to store the
+ * time at which the queue remains with no backlog and
+ * no outstanding request; used by the weight-raising
+ * mechanism).
+ */
+ bfqq->budget_timeout = jiffies;
+
+ bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+ }
+
+ now_ns = ktime_get_ns();
+
+ bfqq->ttime.last_end_request = now_ns;
+
+ /*
+ * Using us instead of ns, to get a reasonable precision in
+ * computing rate in next check.
+ */
+ delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
+
+ /*
+ * If the request took rather long to complete, and, according
+ * to the maximum request size recorded, this completion latency
+ * implies that the request was certainly served at a very low
+ * rate (less than 1M sectors/sec), then the whole observation
+ * interval that lasts up to this time instant cannot be a
+ * valid time interval for computing a new peak rate. Invoke
+ * bfq_update_rate_reset to have the following three steps
+ * taken:
+ * - close the observation interval at the last (previous)
+ * request dispatch or completion
+ * - compute rate, if possible, for that observation interval
+ * - reset to zero samples, which will trigger a proper
+ * re-initialization of the observation interval on next
+ * dispatch
+ */
+ if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC &&
+ (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us <
+ 1UL<<(BFQ_RATE_SHIFT - 10))
+ bfq_update_rate_reset(bfqd, NULL);
+ bfqd->last_completion = now_ns;
+
+ /*
+ * If we are waiting to discover whether the request pattern
+ * of the task associated with the queue is actually
+ * isochronous, and both requisites for this condition to hold
+ * are now satisfied, then compute soft_rt_next_start (see the
+ * comments on the function bfq_bfqq_softrt_next_start()). We
+ * schedule this delayed check when bfqq expires, if it still
+ * has in-flight requests.
+ */
+ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
+ RB_EMPTY_ROOT(&bfqq->sort_list))
+ bfqq->soft_rt_next_start =
+ bfq_bfqq_softrt_next_start(bfqd, bfqq);
+
+ /*
+ * If this is the in-service queue, check if it needs to be expired,
+ * or if we want to idle in case it has no pending requests.
+ */
+ if (bfqd->in_service_queue == bfqq) {
+ if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) {
+ bfq_arm_slice_timer(bfqd);
+ return;
+ } else if (bfq_may_expire_for_budg_timeout(bfqq))
+ bfq_bfqq_expire(bfqd, bfqq, false,
+ BFQQE_BUDGET_TIMEOUT);
+ else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
+ (bfqq->dispatched == 0 ||
+ !bfq_bfqq_may_idle(bfqq)))
+ bfq_bfqq_expire(bfqd, bfqq, false,
+ BFQQE_NO_MORE_REQUESTS);
+ }
+}
+
+static void bfq_put_rq_priv_body(struct bfq_queue *bfqq)
+{
+ bfqq->allocated--;
+
+ bfq_put_queue(bfqq);
+}
+
+static void bfq_put_rq_private(struct request_queue *q, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ if (rq->rq_flags & RQF_STARTED)
+ bfqg_stats_update_completion(bfqq_group(bfqq),
+ rq_start_time_ns(rq),
+ rq_io_start_time_ns(rq),
+ rq->cmd_flags);
+
+ if (likely(rq->rq_flags & RQF_STARTED)) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&bfqd->lock, flags);
+
+ bfq_completed_request(bfqq, bfqd);
+ bfq_put_rq_priv_body(bfqq);
+
+ spin_unlock_irqrestore(&bfqd->lock, flags);
+ } else {
+ /*
+ * Request rq may be still/already in the scheduler,
+ * in which case we need to remove it. And we cannot
+ * defer such a check and removal, to avoid
+ * inconsistencies in the time interval from the end
+ * of this function to the start of the deferred work.
+ * This situation seems to occur only in process
+ * context, as a consequence of a merge. In the
+ * current version of the code, this implies that the
+ * lock is held.
+ */
+
+ if (!RB_EMPTY_NODE(&rq->rb_node))
+ bfq_remove_request(q, rq);
+ bfq_put_rq_priv_body(bfqq);
+ }
+
+ rq->elv.priv[0] = NULL;
+ rq->elv.priv[1] = NULL;
+}
+
+/*
+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
+ * was the last process referring to that bfqq.
+ */
+static struct bfq_queue *
+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
+
+ if (bfqq_process_refs(bfqq) == 1) {
+ bfqq->pid = current->pid;
+ bfq_clear_bfqq_coop(bfqq);
+ bfq_clear_bfqq_split_coop(bfqq);
+ return bfqq;
+ }
+
+ bic_set_bfqq(bic, NULL, 1);
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq);
+ return NULL;
+}
+
+static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd,
+ struct bfq_io_cq *bic,
+ struct bio *bio,
+ bool split, bool is_sync,
+ bool *new_queue)
+{
+ struct bfq_queue *bfqq = bic_to_bfqq(bic, is_sync);
+
+ if (likely(bfqq && bfqq != &bfqd->oom_bfqq))
+ return bfqq;
+
+ if (new_queue)
+ *new_queue = true;
+
+ if (bfqq)
+ bfq_put_queue(bfqq);
+ bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
+
+ bic_set_bfqq(bic, bfqq, is_sync);
+ if (split && is_sync) {
+ if ((bic->was_in_burst_list && bfqd->large_burst) ||
+ bic->saved_in_large_burst)
+ bfq_mark_bfqq_in_large_burst(bfqq);
+ else {
+ bfq_clear_bfqq_in_large_burst(bfqq);
+ if (bic->was_in_burst_list)
+ hlist_add_head(&bfqq->burst_list_node,
+ &bfqd->burst_list);
+ }
+ bfqq->split_time = jiffies;
+ }
+
+ return bfqq;
+}
+
+/*
+ * Allocate bfq data structures associated with this request.
+ */
+static int bfq_get_rq_private(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
+ const int is_sync = rq_is_sync(rq);
+ struct bfq_queue *bfqq;
+ bool new_queue = false;
+ bool split = false;
+
+ spin_lock_irq(&bfqd->lock);
+
+ if (!bic)
+ goto queue_fail;
+
+ bfq_check_ioprio_change(bic, bio);
+
+ bfq_bic_update_cgroup(bic, bio);
+
+ bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, false, is_sync,
+ &new_queue);
+
+ if (likely(!new_queue)) {
+ /* If the queue was seeky for too long, break it apart. */
+ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
+ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
+
+ /* Update bic before losing reference to bfqq */
+ if (bfq_bfqq_in_large_burst(bfqq))
+ bic->saved_in_large_burst = true;
+
+ bfqq = bfq_split_bfqq(bic, bfqq);
+ split = true;
+
+ if (!bfqq)
+ bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio,
+ true, is_sync,
+ NULL);
+ }
+ }
+
+ bfqq->allocated++;
+ bfqq->ref++;
+ bfq_log_bfqq(bfqd, bfqq, "get_request %p: bfqq %p, %d",
+ rq, bfqq, bfqq->ref);
+
+ rq->elv.priv[0] = bic;
+ rq->elv.priv[1] = bfqq;
+
+ /*
+ * If a bfq_queue has only one process reference, it is owned
+ * by only this bic: we can then set bfqq->bic = bic. in
+ * addition, if the queue has also just been split, we have to
+ * resume its state.
+ */
+ if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
+ bfqq->bic = bic;
+ if (split) {
+ /*
+ * The queue has just been split from a shared
+ * queue: restore the idle window and the
+ * possible weight raising period.
+ */
+ bfq_bfqq_resume_state(bfqq, bic);
+ }
+ }
+
+ if (unlikely(bfq_bfqq_just_created(bfqq)))
+ bfq_handle_burst(bfqd, bfqq);
+
+ spin_unlock_irq(&bfqd->lock);
+
+ return 0;
+
+queue_fail:
+ spin_unlock_irq(&bfqd->lock);
+
+ return 1;
+}
+
+static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+ enum bfqq_expiration reason;
+ unsigned long flags;
+
+ spin_lock_irqsave(&bfqd->lock, flags);
+ bfq_clear_bfqq_wait_request(bfqq);
+
+ if (bfqq != bfqd->in_service_queue) {
+ spin_unlock_irqrestore(&bfqd->lock, flags);
+ return;
+ }
+
+ if (bfq_bfqq_budget_timeout(bfqq))
+ /*
+ * Also here the queue can be safely expired
+ * for budget timeout without wasting
+ * guarantees
+ */
+ reason = BFQQE_BUDGET_TIMEOUT;
+ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
+ /*
+ * The queue may not be empty upon timer expiration,
+ * because we may not disable the timer when the
+ * first request of the in-service queue arrives
+ * during disk idling.
+ */
+ reason = BFQQE_TOO_IDLE;
+ else
+ goto schedule_dispatch;
+
+ bfq_bfqq_expire(bfqd, bfqq, true, reason);
+
+schedule_dispatch:
+ spin_unlock_irqrestore(&bfqd->lock, flags);
+ bfq_schedule_dispatch(bfqd);
+}
+
+/*
+ * Handler of the expiration of the timer running if the in-service queue
+ * is idling inside its time slice.
+ */
+static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
+{
+ struct bfq_data *bfqd = container_of(timer, struct bfq_data,
+ idle_slice_timer);
+ struct bfq_queue *bfqq = bfqd->in_service_queue;
+
+ /*
+ * Theoretical race here: the in-service queue can be NULL or
+ * different from the queue that was idling if a new request
+ * arrives for the current queue and there is a full dispatch
+ * cycle that changes the in-service queue. This can hardly
+ * happen, but in the worst case we just expire a queue too
+ * early.
+ */
+ if (bfqq)
+ bfq_idle_slice_timer_body(bfqq);
+
+ return HRTIMER_NORESTART;
+}
+
+static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
+ struct bfq_queue **bfqq_ptr)
+{
+ struct bfq_queue *bfqq = *bfqq_ptr;
+
+ bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
+ if (bfqq) {
+ bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
+
+ bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
+ bfqq, bfqq->ref);
+ bfq_put_queue(bfqq);
+ *bfqq_ptr = NULL;
+ }
+}
+
+/*
+ * Release all the bfqg references to its async queues. If we are
+ * deallocating the group these queues may still contain requests, so
+ * we reparent them to the root cgroup (i.e., the only one that will
+ * exist for sure until all the requests on a device are gone).
+ */
+void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
+
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
+}
+
+static void bfq_exit_queue(struct elevator_queue *e)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ struct bfq_queue *bfqq, *n;
+
+ hrtimer_cancel(&bfqd->idle_slice_timer);
+
+ spin_lock_irq(&bfqd->lock);
+ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
+ bfq_deactivate_bfqq(bfqd, bfqq, false, false);
+ spin_unlock_irq(&bfqd->lock);
+
+ hrtimer_cancel(&bfqd->idle_slice_timer);
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ blkcg_deactivate_policy(bfqd->queue, &blkcg_policy_bfq);
+#else
+ spin_lock_irq(&bfqd->lock);
+ bfq_put_async_queues(bfqd, bfqd->root_group);
+ kfree(bfqd->root_group);
+ spin_unlock_irq(&bfqd->lock);
+#endif
+
+ kfree(bfqd);
+}
+
+static void bfq_init_root_group(struct bfq_group *root_group,
+ struct bfq_data *bfqd)
+{
+ int i;
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ root_group->entity.parent = NULL;
+ root_group->my_entity = NULL;
+ root_group->bfqd = bfqd;
+#endif
+ root_group->rq_pos_tree = RB_ROOT;
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+ root_group->sched_data.bfq_class_idle_last_service = jiffies;
+}
+
+static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+{
+ struct bfq_data *bfqd;
+ struct elevator_queue *eq;
+
+ eq = elevator_alloc(q, e);
+ if (!eq)
+ return -ENOMEM;
+
+ bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
+ if (!bfqd) {
+ kobject_put(&eq->kobj);
+ return -ENOMEM;
+ }
+ eq->elevator_data = bfqd;
+
+ spin_lock_irq(q->queue_lock);
+ q->elevator = eq;
+ spin_unlock_irq(q->queue_lock);
+
+ /*
+ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
+ * Grab a permanent reference to it, so that the normal code flow
+ * will not attempt to free it.
+ */
+ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
+ bfqd->oom_bfqq.ref++;
+ bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
+ bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
+ bfqd->oom_bfqq.entity.new_weight =
+ bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
+
+ /* oom_bfqq does not participate to bursts */
+ bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
+
+ /*
+ * Trigger weight initialization, according to ioprio, at the
+ * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
+ * class won't be changed any more.
+ */
+ bfqd->oom_bfqq.entity.prio_changed = 1;
+
+ bfqd->queue = q;
+
+ INIT_LIST_HEAD(&bfqd->dispatch);
+
+ hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
+ HRTIMER_MODE_REL);
+ bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
+
+ bfqd->queue_weights_tree = RB_ROOT;
+ bfqd->group_weights_tree = RB_ROOT;
+
+ INIT_LIST_HEAD(&bfqd->active_list);
+ INIT_LIST_HEAD(&bfqd->idle_list);
+ INIT_HLIST_HEAD(&bfqd->burst_list);
+
+ bfqd->hw_tag = -1;
+
+ bfqd->bfq_max_budget = bfq_default_max_budget;
+
+ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
+ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
+ bfqd->bfq_back_max = bfq_back_max;
+ bfqd->bfq_back_penalty = bfq_back_penalty;
+ bfqd->bfq_slice_idle = bfq_slice_idle;
+ bfqd->bfq_timeout = bfq_timeout;
+
+ bfqd->bfq_requests_within_timer = 120;
+
+ bfqd->bfq_large_burst_thresh = 8;
+ bfqd->bfq_burst_interval = msecs_to_jiffies(180);
+
+ bfqd->low_latency = true;
+
+ /*
+ * Trade-off between responsiveness and fairness.
+ */
+ bfqd->bfq_wr_coeff = 30;
+ bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
+ bfqd->bfq_wr_max_time = 0;
+ bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
+ bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
+ bfqd->bfq_wr_max_softrt_rate = 7000; /*
+ * Approximate rate required
+ * to playback or record a
+ * high-definition compressed
+ * video.
+ */
+ bfqd->wr_busy_queues = 0;
+
+ /*
+ * Begin by assuming, optimistically, that the device is a
+ * high-speed one, and that its peak rate is equal to 2/3 of
+ * the highest reference rate.
+ */
+ bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
+ T_fast[blk_queue_nonrot(bfqd->queue)];
+ bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
+ bfqd->device_speed = BFQ_BFQD_FAST;
+
+ spin_lock_init(&bfqd->lock);
+
+ /*
+ * The invocation of the next bfq_create_group_hierarchy
+ * function is the head of a chain of function calls
+ * (bfq_create_group_hierarchy->blkcg_activate_policy->
+ * blk_mq_freeze_queue) that may lead to the invocation of the
+ * has_work hook function. For this reason,
+ * bfq_create_group_hierarchy is invoked only after all
+ * scheduler data has been initialized, apart from the fields
+ * that can be initialized only after invoking
+ * bfq_create_group_hierarchy. This, in particular, enables
+ * has_work to correctly return false. Of course, to avoid
+ * other inconsistencies, the blk-mq stack must then refrain
+ * from invoking further scheduler hooks before this init
+ * function is finished.
+ */
+ bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
+ if (!bfqd->root_group)
+ goto out_free;
+ bfq_init_root_group(bfqd->root_group, bfqd);
+ bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
+
+
+ return 0;
+
+out_free:
+ kfree(bfqd);
+ kobject_put(&eq->kobj);
+ return -ENOMEM;
+}
+
+static void bfq_slab_kill(void)
+{
+ kmem_cache_destroy(bfq_pool);
+}
+
+static int __init bfq_slab_setup(void)
+{
+ bfq_pool = KMEM_CACHE(bfq_queue, 0);
+ if (!bfq_pool)
+ return -ENOMEM;
+ return 0;
+}
+
+static ssize_t bfq_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%u\n", var);
+}
+
+static ssize_t bfq_var_store(unsigned long *var, const char *page,
+ size_t count)
+{
+ unsigned long new_val;
+ int ret = kstrtoul(page, 10, &new_val);
+
+ if (ret == 0)
+ *var = new_val;
+
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ u64 __data = __VAR; \
+ if (__CONV == 1) \
+ __data = jiffies_to_msecs(__data); \
+ else if (__CONV == 2) \
+ __data = div_u64(__data, NSEC_PER_MSEC); \
+ return bfq_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2);
+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2);
+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2);
+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
+SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
+#undef SHOW_FUNCTION
+
+#define USEC_SHOW_FUNCTION(__FUNC, __VAR) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ u64 __data = __VAR; \
+ __data = div_u64(__data, NSEC_PER_USEC); \
+ return bfq_var_show(__data, (page)); \
+}
+USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle);
+#undef USEC_SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t \
+__FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned long uninitialized_var(__data); \
+ int ret = bfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV == 1) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else if (__CONV == 2) \
+ *(__PTR) = (u64)__data * NSEC_PER_MSEC; \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
+ INT_MAX, 2);
+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
+ INT_MAX, 2);
+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
+ INT_MAX, 0);
+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
+#undef STORE_FUNCTION
+
+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned long uninitialized_var(__data); \
+ int ret = bfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ *(__PTR) = (u64)__data * NSEC_PER_USEC; \
+ return ret; \
+}
+USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
+ UINT_MAX);
+#undef USEC_STORE_FUNCTION
+
+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data == 0)
+ bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
+ else {
+ if (__data > INT_MAX)
+ __data = INT_MAX;
+ bfqd->bfq_max_budget = __data;
+ }
+
+ bfqd->bfq_user_max_budget = __data;
+
+ return ret;
+}
+
+/*
+ * Leaving this name to preserve name compatibility with cfq
+ * parameters, but this timeout is used for both sync and async.
+ */
+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data < 1)
+ __data = 1;
+ else if (__data > INT_MAX)
+ __data = INT_MAX;
+
+ bfqd->bfq_timeout = msecs_to_jiffies(__data);
+ if (bfqd->bfq_user_max_budget == 0)
+ bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
+
+ return ret;
+}
+
+static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data > 1)
+ __data = 1;
+ if (!bfqd->strict_guarantees && __data == 1
+ && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC)
+ bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC;
+
+ bfqd->strict_guarantees = __data;
+
+ return ret;
+}
+
+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data > 1)
+ __data = 1;
+ if (__data == 0 && bfqd->low_latency != 0)
+ bfq_end_wr(bfqd);
+ bfqd->low_latency = __data;
+
+ return ret;
+}
+
+#define BFQ_ATTR(name) \
+ __ATTR(name, 0644, bfq_##name##_show, bfq_##name##_store)
+
+static struct elv_fs_entry bfq_attrs[] = {
+ BFQ_ATTR(fifo_expire_sync),
+ BFQ_ATTR(fifo_expire_async),
+ BFQ_ATTR(back_seek_max),
+ BFQ_ATTR(back_seek_penalty),
+ BFQ_ATTR(slice_idle),
+ BFQ_ATTR(slice_idle_us),
+ BFQ_ATTR(max_budget),
+ BFQ_ATTR(timeout_sync),
+ BFQ_ATTR(strict_guarantees),
+ BFQ_ATTR(low_latency),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_bfq_mq = {
+ .ops.mq = {
+ .get_rq_priv = bfq_get_rq_private,
+ .put_rq_priv = bfq_put_rq_private,
+ .exit_icq = bfq_exit_icq,
+ .insert_requests = bfq_insert_requests,
+ .dispatch_request = bfq_dispatch_request,
+ .next_request = elv_rb_latter_request,
+ .former_request = elv_rb_former_request,
+ .allow_merge = bfq_allow_bio_merge,
+ .bio_merge = bfq_bio_merge,
+ .request_merge = bfq_request_merge,
+ .requests_merged = bfq_requests_merged,
+ .request_merged = bfq_request_merged,
+ .has_work = bfq_has_work,
+ .init_sched = bfq_init_queue,
+ .exit_sched = bfq_exit_queue,
+ },
+
+ .uses_mq = true,
+ .icq_size = sizeof(struct bfq_io_cq),
+ .icq_align = __alignof__(struct bfq_io_cq),
+ .elevator_attrs = bfq_attrs,
+ .elevator_name = "bfq",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init bfq_init(void)
+{
+ int ret;
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ ret = blkcg_policy_register(&blkcg_policy_bfq);
+ if (ret)
+ return ret;
+#endif
+
+ ret = -ENOMEM;
+ if (bfq_slab_setup())
+ goto err_pol_unreg;
+
+ /*
+ * Times to load large popular applications for the typical
+ * systems installed on the reference devices (see the
+ * comments before the definitions of the next two
+ * arrays). Actually, we use slightly slower values, as the
+ * estimated peak rate tends to be smaller than the actual
+ * peak rate. The reason for this last fact is that estimates
+ * are computed over much shorter time intervals than the long
+ * intervals typically used for benchmarking. Why? First, to
+ * adapt more quickly to variations. Second, because an I/O
+ * scheduler cannot rely on a peak-rate-evaluation workload to
+ * be run for a long time.
+ */
+ T_slow[0] = msecs_to_jiffies(3500); /* actually 4 sec */
+ T_slow[1] = msecs_to_jiffies(6000); /* actually 6.5 sec */
+ T_fast[0] = msecs_to_jiffies(7000); /* actually 8 sec */
+ T_fast[1] = msecs_to_jiffies(2500); /* actually 3 sec */
+
+ /*
+ * Thresholds that determine the switch between speed classes
+ * (see the comments before the definition of the array
+ * device_speed_thresh). These thresholds are biased towards
+ * transitions to the fast class. This is safer than the
+ * opposite bias. In fact, a wrong transition to the slow
+ * class results in short weight-raising periods, because the
+ * speed of the device then tends to be higher that the
+ * reference peak rate. On the opposite end, a wrong
+ * transition to the fast class tends to increase
+ * weight-raising periods, because of the opposite reason.
+ */
+ device_speed_thresh[0] = (4 * R_slow[0]) / 3;
+ device_speed_thresh[1] = (4 * R_slow[1]) / 3;
+
+ ret = elv_register(&iosched_bfq_mq);
+ if (ret)
+ goto err_pol_unreg;
+
+ return 0;
+
+err_pol_unreg:
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ blkcg_policy_unregister(&blkcg_policy_bfq);
+#endif
+ return ret;
+}
+
+static void __exit bfq_exit(void)
+{
+ elv_unregister(&iosched_bfq_mq);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ blkcg_policy_unregister(&blkcg_policy_bfq);
+#endif
+ bfq_slab_kill();
+}
+
+module_init(bfq_init);
+module_exit(bfq_exit);
+
+MODULE_AUTHOR("Paolo Valente");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MQ Budget Fair Queueing I/O Scheduler");
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
new file mode 100644
index 000000000000..ae783c06dfd9
--- /dev/null
+++ b/block/bfq-iosched.h
@@ -0,0 +1,941 @@
+/*
+ * Header file for the BFQ I/O scheduler: data structures and
+ * prototypes of interface functions among BFQ components.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#ifndef _BFQ_H
+#define _BFQ_H
+
+#include <linux/blktrace_api.h>
+#include <linux/hrtimer.h>
+#include <linux/blk-cgroup.h>
+
+#define BFQ_IOPRIO_CLASSES 3
+#define BFQ_CL_IDLE_TIMEOUT (HZ/5)
+
+#define BFQ_MIN_WEIGHT 1
+#define BFQ_MAX_WEIGHT 1000
+#define BFQ_WEIGHT_CONVERSION_COEFF 10
+
+#define BFQ_DEFAULT_QUEUE_IOPRIO 4
+
+#define BFQ_WEIGHT_LEGACY_DFL 100
+#define BFQ_DEFAULT_GRP_IOPRIO 0
+#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE
+
+/*
+ * Soft real-time applications are extremely more latency sensitive
+ * than interactive ones. Over-raise the weight of the former to
+ * privilege them against the latter.
+ */
+#define BFQ_SOFTRT_WEIGHT_FACTOR 100
+
+struct bfq_entity;
+
+/**
+ * struct bfq_service_tree - per ioprio_class service tree.
+ *
+ * Each service tree represents a B-WF2Q+ scheduler on its own. Each
+ * ioprio_class has its own independent scheduler, and so its own
+ * bfq_service_tree. All the fields are protected by the queue lock
+ * of the containing bfqd.
+ */
+struct bfq_service_tree {
+ /* tree for active entities (i.e., those backlogged) */
+ struct rb_root active;
+ /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
+ struct rb_root idle;
+
+ /* idle entity with minimum F_i */
+ struct bfq_entity *first_idle;
+ /* idle entity with maximum F_i */
+ struct bfq_entity *last_idle;
+
+ /* scheduler virtual time */
+ u64 vtime;
+ /* scheduler weight sum; active and idle entities contribute to it */
+ unsigned long wsum;
+};
+
+/**
+ * struct bfq_sched_data - multi-class scheduler.
+ *
+ * bfq_sched_data is the basic scheduler queue. It supports three
+ * ioprio_classes, and can be used either as a toplevel queue or as an
+ * intermediate queue on a hierarchical setup. @next_in_service
+ * points to the active entity of the sched_data service trees that
+ * will be scheduled next. It is used to reduce the number of steps
+ * needed for each hierarchical-schedule update.
+ *
+ * The supported ioprio_classes are the same as in CFQ, in descending
+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
+ * Requests from higher priority queues are served before all the
+ * requests from lower priority queues; among requests of the same
+ * queue requests are served according to B-WF2Q+.
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_sched_data {
+ /* entity in service */
+ struct bfq_entity *in_service_entity;
+ /* head-of-line entity (see comments above) */
+ struct bfq_entity *next_in_service;
+ /* array of service trees, one per ioprio_class */
+ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
+ /* last time CLASS_IDLE was served */
+ unsigned long bfq_class_idle_last_service;
+
+};
+
+/**
+ * struct bfq_weight_counter - counter of the number of all active entities
+ * with a given weight.
+ */
+struct bfq_weight_counter {
+ unsigned int weight; /* weight of the entities this counter refers to */
+ unsigned int num_active; /* nr of active entities with this weight */
+ /*
+ * Weights tree member (see bfq_data's @queue_weights_tree and
+ * @group_weights_tree)
+ */
+ struct rb_node weights_node;
+};
+
+/**
+ * struct bfq_entity - schedulable entity.
+ *
+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
+ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each
+ * entity belongs to the sched_data of the parent group in the cgroup
+ * hierarchy. Non-leaf entities have also their own sched_data, stored
+ * in @my_sched_data.
+ *
+ * Each entity stores independently its priority values; this would
+ * allow different weights on different devices, but this
+ * functionality is not exported to userspace by now. Priorities and
+ * weights are updated lazily, first storing the new values into the
+ * new_* fields, then setting the @prio_changed flag. As soon as
+ * there is a transition in the entity state that allows the priority
+ * update to take place the effective and the requested priority
+ * values are synchronized.
+ *
+ * Unless cgroups are used, the weight value is calculated from the
+ * ioprio to export the same interface as CFQ. When dealing with
+ * ``well-behaved'' queues (i.e., queues that do not spend too much
+ * time to consume their budget and have true sequential behavior, and
+ * when there are no external factors breaking anticipation) the
+ * relative weights at each level of the cgroups hierarchy should be
+ * guaranteed. All the fields are protected by the queue lock of the
+ * containing bfqd.
+ */
+struct bfq_entity {
+ /* service_tree member */
+ struct rb_node rb_node;
+ /* pointer to the weight counter associated with this entity */
+ struct bfq_weight_counter *weight_counter;
+
+ /*
+ * Flag, true if the entity is on a tree (either the active or
+ * the idle one of its service_tree) or is in service.
+ */
+ bool on_st;
+
+ /* B-WF2Q+ start and finish timestamps [sectors/weight] */
+ u64 start, finish;
+
+ /* tree the entity is enqueued into; %NULL if not on a tree */
+ struct rb_root *tree;
+
+ /*
+ * minimum start time of the (active) subtree rooted at this
+ * entity; used for O(log N) lookups into active trees
+ */
+ u64 min_start;
+
+ /* amount of service received during the last service slot */
+ int service;
+
+ /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
+ int budget;
+
+ /* weight of the queue */
+ int weight;
+ /* next weight if a change is in progress */
+ int new_weight;
+
+ /* original weight, used to implement weight boosting */
+ int orig_weight;
+
+ /* parent entity, for hierarchical scheduling */
+ struct bfq_entity *parent;
+
+ /*
+ * For non-leaf nodes in the hierarchy, the associated
+ * scheduler queue, %NULL on leaf nodes.
+ */
+ struct bfq_sched_data *my_sched_data;
+ /* the scheduler queue this entity belongs to */
+ struct bfq_sched_data *sched_data;
+
+ /* flag, set to request a weight, ioprio or ioprio_class change */
+ int prio_changed;
+};
+
+struct bfq_group;
+
+/**
+ * struct bfq_ttime - per process thinktime stats.
+ */
+struct bfq_ttime {
+ /* completion time of the last request */
+ u64 last_end_request;
+
+ /* total process thinktime */
+ u64 ttime_total;
+ /* number of thinktime samples */
+ unsigned long ttime_samples;
+ /* average process thinktime */
+ u64 ttime_mean;
+};
+
+/**
+ * struct bfq_queue - leaf schedulable entity.
+ *
+ * A bfq_queue is a leaf request queue; it can be associated with an
+ * io_context or more, if it is async or shared between cooperating
+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
+ * does not disappear while a bfqq still references it (mostly to avoid
+ * races between request issuing and task migration followed by cgroup
+ * destruction).
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_queue {
+ /* reference counter */
+ int ref;
+ /* parent bfq_data */
+ struct bfq_data *bfqd;
+
+ /* current ioprio and ioprio class */
+ unsigned short ioprio, ioprio_class;
+ /* next ioprio and ioprio class if a change is in progress */
+ unsigned short new_ioprio, new_ioprio_class;
+
+ /*
+ * Shared bfq_queue if queue is cooperating with one or more
+ * other queues.
+ */
+ struct bfq_queue *new_bfqq;
+ /* request-position tree member (see bfq_group's @rq_pos_tree) */
+ struct rb_node pos_node;
+ /* request-position tree root (see bfq_group's @rq_pos_tree) */
+ struct rb_root *pos_root;
+
+ /* sorted list of pending requests */
+ struct rb_root sort_list;
+ /* if fifo isn't expired, next request to serve */
+ struct request *next_rq;
+ /* number of sync and async requests queued */
+ int queued[2];
+ /* number of requests currently allocated */
+ int allocated;
+ /* number of pending metadata requests */
+ int meta_pending;
+ /* fifo list of requests in sort_list */
+ struct list_head fifo;
+
+ /* entity representing this queue in the scheduler */
+ struct bfq_entity entity;
+
+ /* maximum budget allowed from the feedback mechanism */
+ int max_budget;
+ /* budget expiration (in jiffies) */
+ unsigned long budget_timeout;
+
+ /* number of requests on the dispatch list or inside driver */
+ int dispatched;
+
+ /* status flags */
+ unsigned long flags;
+
+ /* node for active/idle bfqq list inside parent bfqd */
+ struct list_head bfqq_list;
+
+ /* associated @bfq_ttime struct */
+ struct bfq_ttime ttime;
+
+ /* bit vector: a 1 for each seeky requests in history */
+ u32 seek_history;
+
+ /* node for the device's burst list */
+ struct hlist_node burst_list_node;
+
+ /* position of the last request enqueued */
+ sector_t last_request_pos;
+
+ /* Number of consecutive pairs of request completion and
+ * arrival, such that the queue becomes idle after the
+ * completion, but the next request arrives within an idle
+ * time slice; used only if the queue's IO_bound flag has been
+ * cleared.
+ */
+ unsigned int requests_within_timer;
+
+ /* pid of the process owning the queue, used for logging purposes */
+ pid_t pid;
+
+ /*
+ * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
+ * if the queue is shared.
+ */
+ struct bfq_io_cq *bic;
+
+ /* current maximum weight-raising time for this queue */
+ unsigned long wr_cur_max_time;
+ /*
+ * Minimum time instant such that, only if a new request is
+ * enqueued after this time instant in an idle @bfq_queue with
+ * no outstanding requests, then the task associated with the
+ * queue it is deemed as soft real-time (see the comments on
+ * the function bfq_bfqq_softrt_next_start())
+ */
+ unsigned long soft_rt_next_start;
+ /*
+ * Start time of the current weight-raising period if
+ * the @bfq-queue is being weight-raised, otherwise
+ * finish time of the last weight-raising period.
+ */
+ unsigned long last_wr_start_finish;
+ /* factor by which the weight of this queue is multiplied */
+ unsigned int wr_coeff;
+ /*
+ * Time of the last transition of the @bfq_queue from idle to
+ * backlogged.
+ */
+ unsigned long last_idle_bklogged;
+ /*
+ * Cumulative service received from the @bfq_queue since the
+ * last transition from idle to backlogged.
+ */
+ unsigned long service_from_backlogged;
+
+ /*
+ * Value of wr start time when switching to soft rt
+ */
+ unsigned long wr_start_at_switch_to_srt;
+
+ unsigned long split_time; /* time of last split */
+};
+
+/**
+ * struct bfq_io_cq - per (request_queue, io_context) structure.
+ */
+struct bfq_io_cq {
+ /* associated io_cq structure */
+ struct io_cq icq; /* must be the first member */
+ /* array of two process queues, the sync and the async */
+ struct bfq_queue *bfqq[2];
+ /* per (request_queue, blkcg) ioprio */
+ int ioprio;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ uint64_t blkcg_serial_nr; /* the current blkcg serial */
+#endif
+ /*
+ * Snapshot of the idle window before merging; taken to
+ * remember this value while the queue is merged, so as to be
+ * able to restore it in case of split.
+ */
+ bool saved_idle_window;
+ /*
+ * Same purpose as the previous two fields for the I/O bound
+ * classification of a queue.
+ */
+ bool saved_IO_bound;
+
+ /*
+ * Same purpose as the previous fields for the value of the
+ * field keeping the queue's belonging to a large burst
+ */
+ bool saved_in_large_burst;
+ /*
+ * True if the queue belonged to a burst list before its merge
+ * with another cooperating queue.
+ */
+ bool was_in_burst_list;
+
+ /*
+ * Similar to previous fields: save wr information.
+ */
+ unsigned long saved_wr_coeff;
+ unsigned long saved_last_wr_start_finish;
+ unsigned long saved_wr_start_at_switch_to_srt;
+ unsigned int saved_wr_cur_max_time;
+ struct bfq_ttime saved_ttime;
+};
+
+enum bfq_device_speed {
+ BFQ_BFQD_FAST,
+ BFQ_BFQD_SLOW,
+};
+
+/**
+ * struct bfq_data - per-device data structure.
+ *
+ * All the fields are protected by @lock.
+ */
+struct bfq_data {
+ /* device request queue */
+ struct request_queue *queue;
+ /* dispatch queue */
+ struct list_head dispatch;
+
+ /* root bfq_group for the device */
+ struct bfq_group *root_group;
+
+ /*
+ * rbtree of weight counters of @bfq_queues, sorted by
+ * weight. Used to keep track of whether all @bfq_queues have
+ * the same weight. The tree contains one counter for each
+ * distinct weight associated to some active and not
+ * weight-raised @bfq_queue (see the comments to the functions
+ * bfq_weights_tree_[add|remove] for further details).
+ */
+ struct rb_root queue_weights_tree;
+ /*
+ * rbtree of non-queue @bfq_entity weight counters, sorted by
+ * weight. Used to keep track of whether all @bfq_groups have
+ * the same weight. The tree contains one counter for each
+ * distinct weight associated to some active @bfq_group (see
+ * the comments to the functions bfq_weights_tree_[add|remove]
+ * for further details).
+ */
+ struct rb_root group_weights_tree;
+
+ /*
+ * Number of bfq_queues containing requests (including the
+ * queue in service, even if it is idling).
+ */
+ int busy_queues;
+ /* number of weight-raised busy @bfq_queues */
+ int wr_busy_queues;
+ /* number of queued requests */
+ int queued;
+ /* number of requests dispatched and waiting for completion */
+ int rq_in_driver;
+
+ /*
+ * Maximum number of requests in driver in the last
+ * @hw_tag_samples completed requests.
+ */
+ int max_rq_in_driver;
+ /* number of samples used to calculate hw_tag */
+ int hw_tag_samples;
+ /* flag set to one if the driver is showing a queueing behavior */
+ int hw_tag;
+
+ /* number of budgets assigned */
+ int budgets_assigned;
+
+ /*
+ * Timer set when idling (waiting) for the next request from
+ * the queue in service.
+ */
+ struct hrtimer idle_slice_timer;
+
+ /* bfq_queue in service */
+ struct bfq_queue *in_service_queue;
+
+ /* on-disk position of the last served request */
+ sector_t last_position;
+
+ /* time of last request completion (ns) */
+ u64 last_completion;
+
+ /* time of first rq dispatch in current observation interval (ns) */
+ u64 first_dispatch;
+ /* time of last rq dispatch in current observation interval (ns) */
+ u64 last_dispatch;
+
+ /* beginning of the last budget */
+ ktime_t last_budget_start;
+ /* beginning of the last idle slice */
+ ktime_t last_idling_start;
+
+ /* number of samples in current observation interval */
+ int peak_rate_samples;
+ /* num of samples of seq dispatches in current observation interval */
+ u32 sequential_samples;
+ /* total num of sectors transferred in current observation interval */
+ u64 tot_sectors_dispatched;
+ /* max rq size seen during current observation interval (sectors) */
+ u32 last_rq_max_size;
+ /* time elapsed from first dispatch in current observ. interval (us) */
+ u64 delta_from_first;
+ /*
+ * Current estimate of the device peak rate, measured in
+ * [BFQ_RATE_SHIFT * sectors/usec]. The left-shift by
+ * BFQ_RATE_SHIFT is performed to increase precision in
+ * fixed-point calculations.
+ */
+ u32 peak_rate;
+
+ /* maximum budget allotted to a bfq_queue before rescheduling */
+ int bfq_max_budget;
+
+ /* list of all the bfq_queues active on the device */
+ struct list_head active_list;
+ /* list of all the bfq_queues idle on the device */
+ struct list_head idle_list;
+
+ /*
+ * Timeout for async/sync requests; when it fires, requests
+ * are served in fifo order.
+ */
+ u64 bfq_fifo_expire[2];
+ /* weight of backward seeks wrt forward ones */
+ unsigned int bfq_back_penalty;
+ /* maximum allowed backward seek */
+ unsigned int bfq_back_max;
+ /* maximum idling time */
+ u32 bfq_slice_idle;
+
+ /* user-configured max budget value (0 for auto-tuning) */
+ int bfq_user_max_budget;
+ /*
+ * Timeout for bfq_queues to consume their budget; used to
+ * prevent seeky queues from imposing long latencies to
+ * sequential or quasi-sequential ones (this also implies that
+ * seeky queues cannot receive guarantees in the service
+ * domain; after a timeout they are charged for the time they
+ * have been in service, to preserve fairness among them, but
+ * without service-domain guarantees).
+ */
+ unsigned int bfq_timeout;
+
+ /*
+ * Number of consecutive requests that must be issued within
+ * the idle time slice to set again idling to a queue which
+ * was marked as non-I/O-bound (see the definition of the
+ * IO_bound flag for further details).
+ */
+ unsigned int bfq_requests_within_timer;
+
+ /*
+ * Force device idling whenever needed to provide accurate
+ * service guarantees, without caring about throughput
+ * issues. CAVEAT: this may even increase latencies, in case
+ * of useless idling for processes that did stop doing I/O.
+ */
+ bool strict_guarantees;
+
+ /*
+ * Last time at which a queue entered the current burst of
+ * queues being activated shortly after each other; for more
+ * details about this and the following parameters related to
+ * a burst of activations, see the comments on the function
+ * bfq_handle_burst.
+ */
+ unsigned long last_ins_in_burst;
+ /*
+ * Reference time interval used to decide whether a queue has
+ * been activated shortly after @last_ins_in_burst.
+ */
+ unsigned long bfq_burst_interval;
+ /* number of queues in the current burst of queue activations */
+ int burst_size;
+
+ /* common parent entity for the queues in the burst */
+ struct bfq_entity *burst_parent_entity;
+ /* Maximum burst size above which the current queue-activation
+ * burst is deemed as 'large'.
+ */
+ unsigned long bfq_large_burst_thresh;
+ /* true if a large queue-activation burst is in progress */
+ bool large_burst;
+ /*
+ * Head of the burst list (as for the above fields, more
+ * details in the comments on the function bfq_handle_burst).
+ */
+ struct hlist_head burst_list;
+
+ /* if set to true, low-latency heuristics are enabled */
+ bool low_latency;
+ /*
+ * Maximum factor by which the weight of a weight-raised queue
+ * is multiplied.
+ */
+ unsigned int bfq_wr_coeff;
+ /* maximum duration of a weight-raising period (jiffies) */
+ unsigned int bfq_wr_max_time;
+
+ /* Maximum weight-raising duration for soft real-time processes */
+ unsigned int bfq_wr_rt_max_time;
+ /*
+ * Minimum idle period after which weight-raising may be
+ * reactivated for a queue (in jiffies).
+ */
+ unsigned int bfq_wr_min_idle_time;
+ /*
+ * Minimum period between request arrivals after which
+ * weight-raising may be reactivated for an already busy async
+ * queue (in jiffies).
+ */
+ unsigned long bfq_wr_min_inter_arr_async;
+
+ /* Max service-rate for a soft real-time queue, in sectors/sec */
+ unsigned int bfq_wr_max_softrt_rate;
+ /*
+ * Cached value of the product R*T, used for computing the
+ * maximum duration of weight raising automatically.
+ */
+ u64 RT_prod;
+ /* device-speed class for the low-latency heuristic */
+ enum bfq_device_speed device_speed;
+
+ /* fallback dummy bfqq for extreme OOM conditions */
+ struct bfq_queue oom_bfqq;
+
+ spinlock_t lock;
+
+ /*
+ * bic associated with the task issuing current bio for
+ * merging. This and the next field are used as a support to
+ * be able to perform the bic lookup, needed by bio-merge
+ * functions, before the scheduler lock is taken, and thus
+ * avoid taking the request-queue lock while the scheduler
+ * lock is being held.
+ */
+ struct bfq_io_cq *bio_bic;
+ /* bfqq associated with the task issuing current bio for merging */
+ struct bfq_queue *bio_bfqq;
+};
+
+enum bfqq_state_flags {
+ BFQQF_just_created = 0, /* queue just allocated */
+ BFQQF_busy, /* has requests or is in service */
+ BFQQF_wait_request, /* waiting for a request */
+ BFQQF_non_blocking_wait_rq, /*
+ * waiting for a request
+ * without idling the device
+ */
+ BFQQF_fifo_expire, /* FIFO checked in this slice */
+ BFQQF_idle_window, /* slice idling enabled */
+ BFQQF_sync, /* synchronous queue */
+ BFQQF_IO_bound, /*
+ * bfqq has timed-out at least once
+ * having consumed at most 2/10 of
+ * its budget
+ */
+ BFQQF_in_large_burst, /*
+ * bfqq activated in a large burst,
+ * see comments to bfq_handle_burst.
+ */
+ BFQQF_softrt_update, /*
+ * may need softrt-next-start
+ * update
+ */
+ BFQQF_coop, /* bfqq is shared */
+ BFQQF_split_coop /* shared bfqq will be split */
+};
+
+#define BFQ_BFQQ_FNS(name) \
+void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \
+void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \
+int bfq_bfqq_##name(const struct bfq_queue *bfqq);
+
+BFQ_BFQQ_FNS(just_created);
+BFQ_BFQQ_FNS(busy);
+BFQ_BFQQ_FNS(wait_request);
+BFQ_BFQQ_FNS(non_blocking_wait_rq);
+BFQ_BFQQ_FNS(fifo_expire);
+BFQ_BFQQ_FNS(idle_window);
+BFQ_BFQQ_FNS(sync);
+BFQ_BFQQ_FNS(IO_bound);
+BFQ_BFQQ_FNS(in_large_burst);
+BFQ_BFQQ_FNS(coop);
+BFQ_BFQQ_FNS(split_coop);
+BFQ_BFQQ_FNS(softrt_update);
+#undef BFQ_BFQQ_FNS
+
+/* Expiration reasons. */
+enum bfqq_expiration {
+ BFQQE_TOO_IDLE = 0, /*
+ * queue has been idling for
+ * too long
+ */
+ BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */
+ BFQQE_BUDGET_EXHAUSTED, /* budget consumed */
+ BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */
+ BFQQE_PREEMPTED /* preemption in progress */
+};
+
+struct bfqg_stats {
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ /* number of ios merged */
+ struct blkg_rwstat merged;
+ /* total time spent on device in ns, may not be accurate w/ queueing */
+ struct blkg_rwstat service_time;
+ /* total time spent waiting in scheduler queue in ns */
+ struct blkg_rwstat wait_time;
+ /* number of IOs queued up */
+ struct blkg_rwstat queued;
+ /* total disk time and nr sectors dispatched by this group */
+ struct blkg_stat time;
+ /* sum of number of ios queued across all samples */
+ struct blkg_stat avg_queue_size_sum;
+ /* count of samples taken for average */
+ struct blkg_stat avg_queue_size_samples;
+ /* how many times this group has been removed from service tree */
+ struct blkg_stat dequeue;
+ /* total time spent waiting for it to be assigned a timeslice. */
+ struct blkg_stat group_wait_time;
+ /* time spent idling for this blkcg_gq */
+ struct blkg_stat idle_time;
+ /* total time with empty current active q with other requests queued */
+ struct blkg_stat empty_time;
+ /* fields after this shouldn't be cleared on stat reset */
+ uint64_t start_group_wait_time;
+ uint64_t start_idle_time;
+ uint64_t start_empty_time;
+ uint16_t flags;
+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
+};
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+
+/*
+ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
+ *
+ * @ps: @blkcg_policy_storage that this structure inherits
+ * @weight: weight of the bfq_group
+ */
+struct bfq_group_data {
+ /* must be the first member */
+ struct blkcg_policy_data pd;
+
+ unsigned int weight;
+};
+
+/**
+ * struct bfq_group - per (device, cgroup) data structure.
+ * @entity: schedulable entity to insert into the parent group sched_data.
+ * @sched_data: own sched_data, to contain child entities (they may be
+ * both bfq_queues and bfq_groups).
+ * @bfqd: the bfq_data for the device this group acts upon.
+ * @async_bfqq: array of async queues for all the tasks belonging to
+ * the group, one queue per ioprio value per ioprio_class,
+ * except for the idle class that has only one queue.
+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
+ * to avoid too many special cases during group creation/
+ * migration.
+ * @stats: stats for this bfqg.
+ * @active_entities: number of active entities belonging to the group;
+ * unused for the root group. Used to know whether there
+ * are groups with more than one active @bfq_entity
+ * (see the comments to the function
+ * bfq_bfqq_may_idle()).
+ * @rq_pos_tree: rbtree sorted by next_request position, used when
+ * determining if two or more queues have interleaving
+ * requests (see bfq_find_close_cooperator()).
+ *
+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
+ * there is a set of bfq_groups, each one collecting the lower-level
+ * entities belonging to the group that are acting on the same device.
+ *
+ * Locking works as follows:
+ * o @bfqd is protected by the queue lock, RCU is used to access it
+ * from the readers.
+ * o All the other fields are protected by the @bfqd queue lock.
+ */
+struct bfq_group {
+ /* must be the first member */
+ struct blkg_policy_data pd;
+
+ struct bfq_entity entity;
+ struct bfq_sched_data sched_data;
+
+ void *bfqd;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+
+ struct bfq_entity *my_entity;
+
+ int active_entities;
+
+ struct rb_root rq_pos_tree;
+
+ struct bfqg_stats stats;
+};
+
+#else
+struct bfq_group {
+ struct bfq_sched_data sched_data;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+
+ struct rb_root rq_pos_tree;
+};
+#endif
+
+struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
+
+/* --------------- main algorithm interface ----------------- */
+
+#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
+ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
+
+extern const int bfq_timeout;
+
+struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync);
+void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync);
+struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic);
+void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity,
+ struct rb_root *root);
+void bfq_weights_tree_remove(struct bfq_data *bfqd, struct bfq_entity *entity,
+ struct rb_root *root);
+void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool compensate, enum bfqq_expiration reason);
+void bfq_put_queue(struct bfq_queue *bfqq);
+void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
+void bfq_schedule_dispatch(struct bfq_data *bfqd);
+void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
+
+/* ------------ end of main algorithm interface -------------- */
+
+/* ---------------- cgroups-support interface ---------------- */
+
+void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
+ unsigned int op);
+void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op);
+void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op);
+void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time,
+ uint64_t io_start_time, unsigned int op);
+void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
+void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
+void bfqg_stats_update_idle_time(struct bfq_group *bfqg);
+void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg);
+void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg);
+void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_group *bfqg);
+
+void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg);
+void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio);
+void bfq_end_wr_async(struct bfq_data *bfqd);
+struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
+ struct blkcg *blkcg);
+struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
+struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
+struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node);
+void bfqg_put(struct bfq_group *bfqg);
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+extern struct cftype bfq_blkcg_legacy_files[];
+extern struct cftype bfq_blkg_files[];
+extern struct blkcg_policy blkcg_policy_bfq;
+#endif
+
+/* ------------- end of cgroups-support interface ------------- */
+
+/* - interface of the internal hierarchical B-WF2Q+ scheduler - */
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+/* both next loops stop at one of the child entities of the root group */
+#define for_each_entity(entity) \
+ for (; entity ; entity = entity->parent)
+
+/*
+ * For each iteration, compute parent in advance, so as to be safe if
+ * entity is deallocated during the iteration. Such a deallocation may
+ * happen as a consequence of a bfq_put_queue that frees the bfq_queue
+ * containing entity.
+ */
+#define for_each_entity_safe(entity, parent) \
+ for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
+
+#else /* CONFIG_BFQ_GROUP_IOSCHED */
+/*
+ * Next two macros are fake loops when cgroups support is not
+ * enabled. I fact, in such a case, there is only one level to go up
+ * (to reach the root group).
+ */
+#define for_each_entity(entity) \
+ for (; entity ; entity = NULL)
+
+#define for_each_entity_safe(entity, parent) \
+ for (parent = NULL; entity ; entity = parent)
+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
+
+struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq);
+struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
+struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity);
+struct bfq_entity *bfq_entity_of(struct rb_node *node);
+unsigned short bfq_ioprio_to_weight(int ioprio);
+void bfq_put_idle_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity);
+struct bfq_service_tree *
+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
+ struct bfq_entity *entity);
+void bfq_bfqq_served(struct bfq_queue *bfqq, int served);
+void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ unsigned long time_ms);
+bool __bfq_deactivate_entity(struct bfq_entity *entity,
+ bool ins_into_idle_tree);
+bool next_queue_may_preempt(struct bfq_data *bfqd);
+struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd);
+void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd);
+void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool ins_into_idle_tree, bool expiration);
+void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool expiration);
+void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+
+/* --------------- end of interface of B-WF2Q+ ---------------- */
+
+/* Logging facilities. */
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
+
+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \
+ char __pbuf[128]; \
+ \
+ blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
+ blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, (bfqq)->pid, \
+ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
+ __pbuf, ##args); \
+} while (0)
+
+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \
+ char __pbuf[128]; \
+ \
+ blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \
+ blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args); \
+} while (0)
+
+#else /* CONFIG_BFQ_GROUP_IOSCHED */
+
+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \
+ bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \
+ ##args)
+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0)
+
+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
+
+#define bfq_log(bfqd, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
+
+#endif /* _BFQ_H */
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
new file mode 100644
index 000000000000..b4fc3e4260b7
--- /dev/null
+++ b/block/bfq-wf2q.c
@@ -0,0 +1,1616 @@
+/*
+ * Hierarchical Budget Worst-case Fair Weighted Fair Queueing
+ * (B-WF2Q+): hierarchical scheduling algorithm by which the BFQ I/O
+ * scheduler schedules generic entities. The latter can represent
+ * either single bfq queues (associated with processes) or groups of
+ * bfq queues (associated with cgroups).
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include "bfq-iosched.h"
+
+/**
+ * bfq_gt - compare two timestamps.
+ * @a: first ts.
+ * @b: second ts.
+ *
+ * Return @a > @b, dealing with wrapping correctly.
+ */
+static int bfq_gt(u64 a, u64 b)
+{
+ return (s64)(a - b) > 0;
+}
+
+static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree)
+{
+ struct rb_node *node = tree->rb_node;
+
+ return rb_entry(node, struct bfq_entity, rb_node);
+}
+
+static unsigned int bfq_class_idx(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ return bfqq ? bfqq->ioprio_class - 1 :
+ BFQ_DEFAULT_GRP_CLASS - 1;
+}
+
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd);
+
+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
+
+/**
+ * bfq_update_next_in_service - update sd->next_in_service
+ * @sd: sched_data for which to perform the update.
+ * @new_entity: if not NULL, pointer to the entity whose activation,
+ * requeueing or repositionig triggered the invocation of
+ * this function.
+ *
+ * This function is called to update sd->next_in_service, which, in
+ * its turn, may change as a consequence of the insertion or
+ * extraction of an entity into/from one of the active trees of
+ * sd. These insertions/extractions occur as a consequence of
+ * activations/deactivations of entities, with some activations being
+ * 'true' activations, and other activations being requeueings (i.e.,
+ * implementing the second, requeueing phase of the mechanism used to
+ * reposition an entity in its active tree; see comments on
+ * __bfq_activate_entity and __bfq_requeue_entity for details). In
+ * both the last two activation sub-cases, new_entity points to the
+ * just activated or requeued entity.
+ *
+ * Returns true if sd->next_in_service changes in such a way that
+ * entity->parent may become the next_in_service for its parent
+ * entity.
+ */
+static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
+ struct bfq_entity *new_entity)
+{
+ struct bfq_entity *next_in_service = sd->next_in_service;
+ bool parent_sched_may_change = false;
+
+ /*
+ * If this update is triggered by the activation, requeueing
+ * or repositiong of an entity that does not coincide with
+ * sd->next_in_service, then a full lookup in the active tree
+ * can be avoided. In fact, it is enough to check whether the
+ * just-modified entity has a higher priority than
+ * sd->next_in_service, or, even if it has the same priority
+ * as sd->next_in_service, is eligible and has a lower virtual
+ * finish time than sd->next_in_service. If this compound
+ * condition holds, then the new entity becomes the new
+ * next_in_service. Otherwise no change is needed.
+ */
+ if (new_entity && new_entity != sd->next_in_service) {
+ /*
+ * Flag used to decide whether to replace
+ * sd->next_in_service with new_entity. Tentatively
+ * set to true, and left as true if
+ * sd->next_in_service is NULL.
+ */
+ bool replace_next = true;
+
+ /*
+ * If there is already a next_in_service candidate
+ * entity, then compare class priorities or timestamps
+ * to decide whether to replace sd->service_tree with
+ * new_entity.
+ */
+ if (next_in_service) {
+ unsigned int new_entity_class_idx =
+ bfq_class_idx(new_entity);
+ struct bfq_service_tree *st =
+ sd->service_tree + new_entity_class_idx;
+
+ /*
+ * For efficiency, evaluate the most likely
+ * sub-condition first.
+ */
+ replace_next =
+ (new_entity_class_idx ==
+ bfq_class_idx(next_in_service)
+ &&
+ !bfq_gt(new_entity->start, st->vtime)
+ &&
+ bfq_gt(next_in_service->finish,
+ new_entity->finish))
+ ||
+ new_entity_class_idx <
+ bfq_class_idx(next_in_service);
+ }
+
+ if (replace_next)
+ next_in_service = new_entity;
+ } else /* invoked because of a deactivation: lookup needed */
+ next_in_service = bfq_lookup_next_entity(sd);
+
+ if (next_in_service) {
+ parent_sched_may_change = !sd->next_in_service ||
+ bfq_update_parent_budget(next_in_service);
+ }
+
+ sd->next_in_service = next_in_service;
+
+ if (!next_in_service)
+ return parent_sched_may_change;
+
+ return parent_sched_may_change;
+}
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+
+struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *group_entity = bfqq->entity.parent;
+
+ if (!group_entity)
+ group_entity = &bfqq->bfqd->root_group->entity;
+
+ return container_of(group_entity, struct bfq_group, entity);
+}
+
+/*
+ * Returns true if this budget changes may let next_in_service->parent
+ * become the next_in_service entity for its parent entity.
+ */
+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
+{
+ struct bfq_entity *bfqg_entity;
+ struct bfq_group *bfqg;
+ struct bfq_sched_data *group_sd;
+ bool ret = false;
+
+ group_sd = next_in_service->sched_data;
+
+ bfqg = container_of(group_sd, struct bfq_group, sched_data);
+ /*
+ * bfq_group's my_entity field is not NULL only if the group
+ * is not the root group. We must not touch the root entity
+ * as it must never become an in-service entity.
+ */
+ bfqg_entity = bfqg->my_entity;
+ if (bfqg_entity) {
+ if (bfqg_entity->budget > next_in_service->budget)
+ ret = true;
+ bfqg_entity->budget = next_in_service->budget;
+ }
+
+ return ret;
+}
+
+/*
+ * This function tells whether entity stops being a candidate for next
+ * service, according to the following logic.
+ *
+ * This function is invoked for an entity that is about to be set in
+ * service. If such an entity is a queue, then the entity is no longer
+ * a candidate for next service (i.e, a candidate entity to serve
+ * after the in-service entity is expired). The function then returns
+ * true.
+ *
+ * In contrast, the entity could stil be a candidate for next service
+ * if it is not a queue, and has more than one child. In fact, even if
+ * one of its children is about to be set in service, other children
+ * may still be the next to serve. As a consequence, a non-queue
+ * entity is not a candidate for next-service only if it has only one
+ * child. And only if this condition holds, then the function returns
+ * true for a non-queue entity.
+ */
+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
+{
+ struct bfq_group *bfqg;
+
+ if (bfq_entity_to_bfqq(entity))
+ return true;
+
+ bfqg = container_of(entity, struct bfq_group, entity);
+
+ if (bfqg->active_entities == 1)
+ return true;
+
+ return false;
+}
+
+#else /* CONFIG_BFQ_GROUP_IOSCHED */
+
+struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
+{
+ return bfqq->bfqd->root_group;
+}
+
+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
+{
+ return false;
+}
+
+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
+{
+ return true;
+}
+
+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
+
+/*
+ * Shift for timestamp calculations. This actually limits the maximum
+ * service allowed in one timestamp delta (small shift values increase it),
+ * the maximum total weight that can be used for the queues in the system
+ * (big shift values increase it), and the period of virtual time
+ * wraparounds.
+ */
+#define WFQ_SERVICE_SHIFT 22
+
+struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = NULL;
+
+ if (!entity->my_sched_data)
+ bfqq = container_of(entity, struct bfq_queue, entity);
+
+ return bfqq;
+}
+
+
+/**
+ * bfq_delta - map service into the virtual time domain.
+ * @service: amount of service.
+ * @weight: scale factor (weight of an entity or weight sum).
+ */
+static u64 bfq_delta(unsigned long service, unsigned long weight)
+{
+ u64 d = (u64)service << WFQ_SERVICE_SHIFT;
+
+ do_div(d, weight);
+ return d;
+}
+
+/**
+ * bfq_calc_finish - assign the finish time to an entity.
+ * @entity: the entity to act upon.
+ * @service: the service to be charged to the entity.
+ */
+static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ entity->finish = entity->start +
+ bfq_delta(service, entity->weight);
+
+ if (bfqq) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: serv %lu, w %d",
+ service, entity->weight);
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: start %llu, finish %llu, delta %llu",
+ entity->start, entity->finish,
+ bfq_delta(service, entity->weight));
+ }
+}
+
+/**
+ * bfq_entity_of - get an entity from a node.
+ * @node: the node field of the entity.
+ *
+ * Convert a node pointer to the relative entity. This is used only
+ * to simplify the logic of some functions and not as the generic
+ * conversion mechanism because, e.g., in the tree walking functions,
+ * the check for a %NULL value would be redundant.
+ */
+struct bfq_entity *bfq_entity_of(struct rb_node *node)
+{
+ struct bfq_entity *entity = NULL;
+
+ if (node)
+ entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ return entity;
+}
+
+/**
+ * bfq_extract - remove an entity from a tree.
+ * @root: the tree root.
+ * @entity: the entity to remove.
+ */
+static void bfq_extract(struct rb_root *root, struct bfq_entity *entity)
+{
+ entity->tree = NULL;
+ rb_erase(&entity->rb_node, root);
+}
+
+/**
+ * bfq_idle_extract - extract an entity from the idle tree.
+ * @st: the service tree of the owning @entity.
+ * @entity: the entity being removed.
+ */
+static void bfq_idle_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *next;
+
+ if (entity == st->first_idle) {
+ next = rb_next(&entity->rb_node);
+ st->first_idle = bfq_entity_of(next);
+ }
+
+ if (entity == st->last_idle) {
+ next = rb_prev(&entity->rb_node);
+ st->last_idle = bfq_entity_of(next);
+ }
+
+ bfq_extract(&st->idle, entity);
+
+ if (bfqq)
+ list_del(&bfqq->bfqq_list);
+}
+
+/**
+ * bfq_insert - generic tree insertion.
+ * @root: tree root.
+ * @entity: entity to insert.
+ *
+ * This is used for the idle and the active tree, since they are both
+ * ordered by finish time.
+ */
+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
+{
+ struct bfq_entity *entry;
+ struct rb_node **node = &root->rb_node;
+ struct rb_node *parent = NULL;
+
+ while (*node) {
+ parent = *node;
+ entry = rb_entry(parent, struct bfq_entity, rb_node);
+
+ if (bfq_gt(entry->finish, entity->finish))
+ node = &parent->rb_left;
+ else
+ node = &parent->rb_right;
+ }
+
+ rb_link_node(&entity->rb_node, parent, node);
+ rb_insert_color(&entity->rb_node, root);
+
+ entity->tree = root;
+}
+
+/**
+ * bfq_update_min - update the min_start field of a entity.
+ * @entity: the entity to update.
+ * @node: one of its children.
+ *
+ * This function is called when @entity may store an invalid value for
+ * min_start due to updates to the active tree. The function assumes
+ * that the subtree rooted at @node (which may be its left or its right
+ * child) has a valid min_start value.
+ */
+static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node)
+{
+ struct bfq_entity *child;
+
+ if (node) {
+ child = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entity->min_start, child->min_start))
+ entity->min_start = child->min_start;
+ }
+}
+
+/**
+ * bfq_update_active_node - recalculate min_start.
+ * @node: the node to update.
+ *
+ * @node may have changed position or one of its children may have moved,
+ * this function updates its min_start value. The left and right subtrees
+ * are assumed to hold a correct min_start value.
+ */
+static void bfq_update_active_node(struct rb_node *node)
+{
+ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ entity->min_start = entity->start;
+ bfq_update_min(entity, node->rb_right);
+ bfq_update_min(entity, node->rb_left);
+}
+
+/**
+ * bfq_update_active_tree - update min_start for the whole active tree.
+ * @node: the starting node.
+ *
+ * @node must be the deepest modified node after an update. This function
+ * updates its min_start using the values held by its children, assuming
+ * that they did not change, and then updates all the nodes that may have
+ * changed in the path to the root. The only nodes that may have changed
+ * are the ones in the path or their siblings.
+ */
+static void bfq_update_active_tree(struct rb_node *node)
+{
+ struct rb_node *parent;
+
+up:
+ bfq_update_active_node(node);
+
+ parent = rb_parent(node);
+ if (!parent)
+ return;
+
+ if (node == parent->rb_left && parent->rb_right)
+ bfq_update_active_node(parent->rb_right);
+ else if (parent->rb_left)
+ bfq_update_active_node(parent->rb_left);
+
+ node = parent;
+ goto up;
+}
+
+/**
+ * bfq_active_insert - insert an entity in the active tree of its
+ * group/device.
+ * @st: the service tree of the entity.
+ * @entity: the entity being inserted.
+ *
+ * The active tree is ordered by finish time, but an extra key is kept
+ * per each node, containing the minimum value for the start times of
+ * its children (and the node itself), so it's possible to search for
+ * the eligible node with the lowest finish time in logarithmic time.
+ */
+static void bfq_active_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node = &entity->rb_node;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_sched_data *sd = NULL;
+ struct bfq_group *bfqg = NULL;
+ struct bfq_data *bfqd = NULL;
+#endif
+
+ bfq_insert(&st->active, entity);
+
+ if (node->rb_left)
+ node = node->rb_left;
+ else if (node->rb_right)
+ node = node->rb_right;
+
+ bfq_update_active_tree(node);
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ sd = entity->sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+#endif
+ if (bfqq)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else /* bfq_group */
+ bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree);
+
+ if (bfqg != bfqd->root_group)
+ bfqg->active_entities++;
+#endif
+}
+
+/**
+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
+ * @ioprio: the ioprio value to convert.
+ */
+unsigned short bfq_ioprio_to_weight(int ioprio)
+{
+ return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
+}
+
+/**
+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
+ * @weight: the weight value to convert.
+ *
+ * To preserve as much as possible the old only-ioprio user interface,
+ * 0 is used as an escape ioprio value for weights (numerically) equal or
+ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF.
+ */
+static unsigned short bfq_weight_to_ioprio(int weight)
+{
+ return max_t(int, 0,
+ IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight);
+}
+
+static void bfq_get_entity(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ if (bfqq) {
+ bfqq->ref++;
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
+ bfqq, bfqq->ref);
+ }
+}
+
+/**
+ * bfq_find_deepest - find the deepest node that an extraction can modify.
+ * @node: the node being removed.
+ *
+ * Do the first step of an extraction in an rb tree, looking for the
+ * node that will replace @node, and returning the deepest node that
+ * the following modifications to the tree can touch. If @node is the
+ * last node in the tree return %NULL.
+ */
+static struct rb_node *bfq_find_deepest(struct rb_node *node)
+{
+ struct rb_node *deepest;
+
+ if (!node->rb_right && !node->rb_left)
+ deepest = rb_parent(node);
+ else if (!node->rb_right)
+ deepest = node->rb_left;
+ else if (!node->rb_left)
+ deepest = node->rb_right;
+ else {
+ deepest = rb_next(node);
+ if (deepest->rb_right)
+ deepest = deepest->rb_right;
+ else if (rb_parent(deepest) != node)
+ deepest = rb_parent(deepest);
+ }
+
+ return deepest;
+}
+
+/**
+ * bfq_active_extract - remove an entity from the active tree.
+ * @st: the service_tree containing the tree.
+ * @entity: the entity being removed.
+ */
+static void bfq_active_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_sched_data *sd = NULL;
+ struct bfq_group *bfqg = NULL;
+ struct bfq_data *bfqd = NULL;
+#endif
+
+ node = bfq_find_deepest(&entity->rb_node);
+ bfq_extract(&st->active, entity);
+
+ if (node)
+ bfq_update_active_tree(node);
+
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ sd = entity->sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+#endif
+ if (bfqq)
+ list_del(&bfqq->bfqq_list);
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else /* bfq_group */
+ bfq_weights_tree_remove(bfqd, entity,
+ &bfqd->group_weights_tree);
+
+ if (bfqg != bfqd->root_group)
+ bfqg->active_entities--;
+#endif
+}
+
+/**
+ * bfq_idle_insert - insert an entity into the idle tree.
+ * @st: the service tree containing the tree.
+ * @entity: the entity to insert.
+ */
+static void bfq_idle_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (!first_idle || bfq_gt(first_idle->finish, entity->finish))
+ st->first_idle = entity;
+ if (!last_idle || bfq_gt(entity->finish, last_idle->finish))
+ st->last_idle = entity;
+
+ bfq_insert(&st->idle, entity);
+
+ if (bfqq)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
+}
+
+/**
+ * bfq_forget_entity - do not consider entity any longer for scheduling
+ * @st: the service tree.
+ * @entity: the entity being removed.
+ * @is_in_service: true if entity is currently the in-service entity.
+ *
+ * Forget everything about @entity. In addition, if entity represents
+ * a queue, and the latter is not in service, then release the service
+ * reference to the queue (the one taken through bfq_get_entity). In
+ * fact, in this case, there is really no more service reference to
+ * the queue, as the latter is also outside any service tree. If,
+ * instead, the queue is in service, then __bfq_bfqd_reset_in_service
+ * will take care of putting the reference when the queue finally
+ * stops being served.
+ */
+static void bfq_forget_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity,
+ bool is_in_service)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ entity->on_st = false;
+ st->wsum -= entity->weight;
+ if (bfqq && !is_in_service)
+ bfq_put_queue(bfqq);
+}
+
+/**
+ * bfq_put_idle_entity - release the idle tree ref of an entity.
+ * @st: service tree for the entity.
+ * @entity: the entity being released.
+ */
+void bfq_put_idle_entity(struct bfq_service_tree *st, struct bfq_entity *entity)
+{
+ bfq_idle_extract(st, entity);
+ bfq_forget_entity(st, entity,
+ entity == entity->sched_data->in_service_entity);
+}
+
+/**
+ * bfq_forget_idle - update the idle tree if necessary.
+ * @st: the service tree to act upon.
+ *
+ * To preserve the global O(log N) complexity we only remove one entry here;
+ * as the idle tree will not grow indefinitely this can be done safely.
+ */
+static void bfq_forget_idle(struct bfq_service_tree *st)
+{
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (RB_EMPTY_ROOT(&st->active) && last_idle &&
+ !bfq_gt(last_idle->finish, st->vtime)) {
+ /*
+ * Forget the whole idle tree, increasing the vtime past
+ * the last finish time of idle entities.
+ */
+ st->vtime = last_idle->finish;
+ }
+
+ if (first_idle && !bfq_gt(first_idle->finish, st->vtime))
+ bfq_put_idle_entity(st, first_idle);
+}
+
+struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sched_data = entity->sched_data;
+ unsigned int idx = bfq_class_idx(entity);
+
+ return sched_data->service_tree + idx;
+}
+
+
+struct bfq_service_tree *
+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
+ struct bfq_entity *entity)
+{
+ struct bfq_service_tree *new_st = old_st;
+
+ if (entity->prio_changed) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ unsigned int prev_weight, new_weight;
+ struct bfq_data *bfqd = NULL;
+ struct rb_root *root;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ struct bfq_sched_data *sd;
+ struct bfq_group *bfqg;
+#endif
+
+ if (bfqq)
+ bfqd = bfqq->bfqd;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+ else {
+ sd = entity->my_sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+ }
+#endif
+
+ old_st->wsum -= entity->weight;
+
+ if (entity->new_weight != entity->orig_weight) {
+ if (entity->new_weight < BFQ_MIN_WEIGHT ||
+ entity->new_weight > BFQ_MAX_WEIGHT) {
+ pr_crit("update_weight_prio: new_weight %d\n",
+ entity->new_weight);
+ if (entity->new_weight < BFQ_MIN_WEIGHT)
+ entity->new_weight = BFQ_MIN_WEIGHT;
+ else
+ entity->new_weight = BFQ_MAX_WEIGHT;
+ }
+ entity->orig_weight = entity->new_weight;
+ if (bfqq)
+ bfqq->ioprio =
+ bfq_weight_to_ioprio(entity->orig_weight);
+ }
+
+ if (bfqq)
+ bfqq->ioprio_class = bfqq->new_ioprio_class;
+ entity->prio_changed = 0;
+
+ /*
+ * NOTE: here we may be changing the weight too early,
+ * this will cause unfairness. The correct approach
+ * would have required additional complexity to defer
+ * weight changes to the proper time instants (i.e.,
+ * when entity->finish <= old_st->vtime).
+ */
+ new_st = bfq_entity_service_tree(entity);
+
+ prev_weight = entity->weight;
+ new_weight = entity->orig_weight *
+ (bfqq ? bfqq->wr_coeff : 1);
+ /*
+ * If the weight of the entity changes, remove the entity
+ * from its old weight counter (if there is a counter
+ * associated with the entity), and add it to the counter
+ * associated with its new weight.
+ */
+ if (prev_weight != new_weight) {
+ root = bfqq ? &bfqd->queue_weights_tree :
+ &bfqd->group_weights_tree;
+ bfq_weights_tree_remove(bfqd, entity, root);
+ }
+ entity->weight = new_weight;
+ /*
+ * Add the entity to its weights tree only if it is
+ * not associated with a weight-raised queue.
+ */
+ if (prev_weight != new_weight &&
+ (bfqq ? bfqq->wr_coeff == 1 : 1))
+ /* If we get here, root has been initialized. */
+ bfq_weights_tree_add(bfqd, entity, root);
+
+ new_st->wsum += entity->weight;
+
+ if (new_st != old_st)
+ entity->start = new_st->vtime;
+ }
+
+ return new_st;
+}
+
+/**
+ * bfq_bfqq_served - update the scheduler status after selection for
+ * service.
+ * @bfqq: the queue being served.
+ * @served: bytes to transfer.
+ *
+ * NOTE: this can be optimized, as the timestamps of upper level entities
+ * are synchronized every time a new bfqq is selected for service. By now,
+ * we keep it to better check consistency.
+ */
+void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st;
+
+ for_each_entity(entity) {
+ st = bfq_entity_service_tree(entity);
+
+ entity->service += served;
+
+ st->vtime += bfq_delta(served, st->wsum);
+ bfq_forget_idle(st);
+ }
+ bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served);
+}
+
+/**
+ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length
+ * of the time interval during which bfqq has been in
+ * service.
+ * @bfqd: the device
+ * @bfqq: the queue that needs a service update.
+ * @time_ms: the amount of time during which the queue has received service
+ *
+ * If a queue does not consume its budget fast enough, then providing
+ * the queue with service fairness may impair throughput, more or less
+ * severely. For this reason, queues that consume their budget slowly
+ * are provided with time fairness instead of service fairness. This
+ * goal is achieved through the BFQ scheduling engine, even if such an
+ * engine works in the service, and not in the time domain. The trick
+ * is charging these queues with an inflated amount of service, equal
+ * to the amount of service that they would have received during their
+ * service slot if they had been fast, i.e., if their requests had
+ * been dispatched at a rate equal to the estimated peak rate.
+ *
+ * It is worth noting that time fairness can cause important
+ * distortions in terms of bandwidth distribution, on devices with
+ * internal queueing. The reason is that I/O requests dispatched
+ * during the service slot of a queue may be served after that service
+ * slot is finished, and may have a total processing time loosely
+ * correlated with the duration of the service slot. This is
+ * especially true for short service slots.
+ */
+void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ unsigned long time_ms)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ int tot_serv_to_charge = entity->service;
+ unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout);
+
+ if (time_ms > 0 && time_ms < timeout_ms)
+ tot_serv_to_charge =
+ (bfqd->bfq_max_budget * time_ms) / timeout_ms;
+
+ if (tot_serv_to_charge < entity->service)
+ tot_serv_to_charge = entity->service;
+
+ /* Increase budget to avoid inconsistencies */
+ if (tot_serv_to_charge > entity->budget)
+ entity->budget = tot_serv_to_charge;
+
+ bfq_bfqq_served(bfqq,
+ max_t(int, 0, tot_serv_to_charge - entity->service));
+}
+
+static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
+ struct bfq_service_tree *st,
+ bool backshifted)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ st = __bfq_entity_update_weight_prio(st, entity);
+ bfq_calc_finish(entity, entity->budget);
+
+ /*
+ * If some queues enjoy backshifting for a while, then their
+ * (virtual) finish timestamps may happen to become lower and
+ * lower than the system virtual time. In particular, if
+ * these queues often happen to be idle for short time
+ * periods, and during such time periods other queues with
+ * higher timestamps happen to be busy, then the backshifted
+ * timestamps of the former queues can become much lower than
+ * the system virtual time. In fact, to serve the queues with
+ * higher timestamps while the ones with lower timestamps are
+ * idle, the system virtual time may be pushed-up to much
+ * higher values than the finish timestamps of the idle
+ * queues. As a consequence, the finish timestamps of all new
+ * or newly activated queues may end up being much larger than
+ * those of lucky queues with backshifted timestamps. The
+ * latter queues may then monopolize the device for a lot of
+ * time. This would simply break service guarantees.
+ *
+ * To reduce this problem, push up a little bit the
+ * backshifted timestamps of the queue associated with this
+ * entity (only a queue can happen to have the backshifted
+ * flag set): just enough to let the finish timestamp of the
+ * queue be equal to the current value of the system virtual
+ * time. This may introduce a little unfairness among queues
+ * with backshifted timestamps, but it does not break
+ * worst-case fairness guarantees.
+ *
+ * As a special case, if bfqq is weight-raised, push up
+ * timestamps much less, to keep very low the probability that
+ * this push up causes the backshifted finish timestamps of
+ * weight-raised queues to become higher than the backshifted
+ * finish timestamps of non weight-raised queues.
+ */
+ if (backshifted && bfq_gt(st->vtime, entity->finish)) {
+ unsigned long delta = st->vtime - entity->finish;
+
+ if (bfqq)
+ delta /= bfqq->wr_coeff;
+
+ entity->start += delta;
+ entity->finish += delta;
+ }
+
+ bfq_active_insert(st, entity);
+}
+
+/**
+ * __bfq_activate_entity - handle activation of entity.
+ * @entity: the entity being activated.
+ * @non_blocking_wait_rq: true if entity was waiting for a request
+ *
+ * Called for a 'true' activation, i.e., if entity is not active and
+ * one of its children receives a new request.
+ *
+ * Basically, this function updates the timestamps of entity and
+ * inserts entity into its active tree, ater possible extracting it
+ * from its idle tree.
+ */
+static void __bfq_activate_entity(struct bfq_entity *entity,
+ bool non_blocking_wait_rq)
+{
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ bool backshifted = false;
+ unsigned long long min_vstart;
+
+ /* See comments on bfq_fqq_update_budg_for_activation */
+ if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
+ backshifted = true;
+ min_vstart = entity->finish;
+ } else
+ min_vstart = st->vtime;
+
+ if (entity->tree == &st->idle) {
+ /*
+ * Must be on the idle tree, bfq_idle_extract() will
+ * check for that.
+ */
+ bfq_idle_extract(st, entity);
+ entity->start = bfq_gt(min_vstart, entity->finish) ?
+ min_vstart : entity->finish;
+ } else {
+ /*
+ * The finish time of the entity may be invalid, and
+ * it is in the past for sure, otherwise the queue
+ * would have been on the idle tree.
+ */
+ entity->start = min_vstart;
+ st->wsum += entity->weight;
+ /*
+ * entity is about to be inserted into a service tree,
+ * and then set in service: get a reference to make
+ * sure entity does not disappear until it is no
+ * longer in service or scheduled for service.
+ */
+ bfq_get_entity(entity);
+
+ entity->on_st = true;
+ }
+
+ bfq_update_fin_time_enqueue(entity, st, backshifted);
+}
+
+/**
+ * __bfq_requeue_entity - handle requeueing or repositioning of an entity.
+ * @entity: the entity being requeued or repositioned.
+ *
+ * Requeueing is needed if this entity stops being served, which
+ * happens if a leaf descendant entity has expired. On the other hand,
+ * repositioning is needed if the next_inservice_entity for the child
+ * entity has changed. See the comments inside the function for
+ * details.
+ *
+ * Basically, this function: 1) removes entity from its active tree if
+ * present there, 2) updates the timestamps of entity and 3) inserts
+ * entity back into its active tree (in the new, right position for
+ * the new values of the timestamps).
+ */
+static void __bfq_requeue_entity(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+
+ if (entity == sd->in_service_entity) {
+ /*
+ * We are requeueing the current in-service entity,
+ * which may have to be done for one of the following
+ * reasons:
+ * - entity represents the in-service queue, and the
+ * in-service queue is being requeued after an
+ * expiration;
+ * - entity represents a group, and its budget has
+ * changed because one of its child entities has
+ * just been either activated or requeued for some
+ * reason; the timestamps of the entity need then to
+ * be updated, and the entity needs to be enqueued
+ * or repositioned accordingly.
+ *
+ * In particular, before requeueing, the start time of
+ * the entity must be moved forward to account for the
+ * service that the entity has received while in
+ * service. This is done by the next instructions. The
+ * finish time will then be updated according to this
+ * new value of the start time, and to the budget of
+ * the entity.
+ */
+ bfq_calc_finish(entity, entity->service);
+ entity->start = entity->finish;
+ /*
+ * In addition, if the entity had more than one child
+ * when set in service, then was not extracted from
+ * the active tree. This implies that the position of
+ * the entity in the active tree may need to be
+ * changed now, because we have just updated the start
+ * time of the entity, and we will update its finish
+ * time in a moment (the requeueing is then, more
+ * precisely, a repositioning in this case). To
+ * implement this repositioning, we: 1) dequeue the
+ * entity here, 2) update the finish time and
+ * requeue the entity according to the new
+ * timestamps below.
+ */
+ if (entity->tree)
+ bfq_active_extract(st, entity);
+ } else { /* The entity is already active, and not in service */
+ /*
+ * In this case, this function gets called only if the
+ * next_in_service entity below this entity has
+ * changed, and this change has caused the budget of
+ * this entity to change, which, finally implies that
+ * the finish time of this entity must be
+ * updated. Such an update may cause the scheduling,
+ * i.e., the position in the active tree, of this
+ * entity to change. We handle this change by: 1)
+ * dequeueing the entity here, 2) updating the finish
+ * time and requeueing the entity according to the new
+ * timestamps below. This is the same approach as the
+ * non-extracted-entity sub-case above.
+ */
+ bfq_active_extract(st, entity);
+ }
+
+ bfq_update_fin_time_enqueue(entity, st, false);
+}
+
+static void __bfq_activate_requeue_entity(struct bfq_entity *entity,
+ struct bfq_sched_data *sd,
+ bool non_blocking_wait_rq)
+{
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+
+ if (sd->in_service_entity == entity || entity->tree == &st->active)
+ /*
+ * in service or already queued on the active tree,
+ * requeue or reposition
+ */
+ __bfq_requeue_entity(entity);
+ else
+ /*
+ * Not in service and not queued on its active tree:
+ * the activity is idle and this is a true activation.
+ */
+ __bfq_activate_entity(entity, non_blocking_wait_rq);
+}
+
+
+/**
+ * bfq_activate_entity - activate or requeue an entity representing a bfq_queue,
+ * and activate, requeue or reposition all ancestors
+ * for which such an update becomes necessary.
+ * @entity: the entity to activate.
+ * @non_blocking_wait_rq: true if this entity was waiting for a request
+ * @requeue: true if this is a requeue, which implies that bfqq is
+ * being expired; thus ALL its ancestors stop being served and must
+ * therefore be requeued
+ */
+static void bfq_activate_requeue_entity(struct bfq_entity *entity,
+ bool non_blocking_wait_rq,
+ bool requeue)
+{
+ struct bfq_sched_data *sd;
+
+ for_each_entity(entity) {
+ sd = entity->sched_data;
+ __bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq);
+
+ if (!bfq_update_next_in_service(sd, entity) && !requeue)
+ break;
+ }
+}
+
+/**
+ * __bfq_deactivate_entity - deactivate an entity from its service tree.
+ * @entity: the entity to deactivate.
+ * @ins_into_idle_tree: if false, the entity will not be put into the
+ * idle tree.
+ *
+ * Deactivates an entity, independently from its previous state. Must
+ * be invoked only if entity is on a service tree. Extracts the entity
+ * from that tree, and if necessary and allowed, puts it on the idle
+ * tree.
+ */
+bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ int is_in_service = entity == sd->in_service_entity;
+
+ if (!entity->on_st) /* entity never activated, or already inactive */
+ return false;
+
+ if (is_in_service)
+ bfq_calc_finish(entity, entity->service);
+
+ if (entity->tree == &st->active)
+ bfq_active_extract(st, entity);
+ else if (!is_in_service && entity->tree == &st->idle)
+ bfq_idle_extract(st, entity);
+
+ if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime))
+ bfq_forget_entity(st, entity, is_in_service);
+ else
+ bfq_idle_insert(st, entity);
+
+ return true;
+}
+
+/**
+ * bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
+ * @entity: the entity to deactivate.
+ * @ins_into_idle_tree: true if the entity can be put on the idle tree
+ */
+static void bfq_deactivate_entity(struct bfq_entity *entity,
+ bool ins_into_idle_tree,
+ bool expiration)
+{
+ struct bfq_sched_data *sd;
+ struct bfq_entity *parent = NULL;
+
+ for_each_entity_safe(entity, parent) {
+ sd = entity->sched_data;
+
+ if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) {
+ /*
+ * entity is not in any tree any more, so
+ * this deactivation is a no-op, and there is
+ * nothing to change for upper-level entities
+ * (in case of expiration, this can never
+ * happen).
+ */
+ return;
+ }
+
+ if (sd->next_in_service == entity)
+ /*
+ * entity was the next_in_service entity,
+ * then, since entity has just been
+ * deactivated, a new one must be found.
+ */
+ bfq_update_next_in_service(sd, NULL);
+
+ if (sd->next_in_service)
+ /*
+ * The parent entity is still backlogged,
+ * because next_in_service is not NULL. So, no
+ * further upwards deactivation must be
+ * performed. Yet, next_in_service has
+ * changed. Then the schedule does need to be
+ * updated upwards.
+ */
+ break;
+
+ /*
+ * If we get here, then the parent is no more
+ * backlogged and we need to propagate the
+ * deactivation upwards. Thus let the loop go on.
+ */
+
+ /*
+ * Also let parent be queued into the idle tree on
+ * deactivation, to preserve service guarantees, and
+ * assuming that who invoked this function does not
+ * need parent entities too to be removed completely.
+ */
+ ins_into_idle_tree = true;
+ }
+
+ /*
+ * If the deactivation loop is fully executed, then there are
+ * no more entities to touch and next loop is not executed at
+ * all. Otherwise, requeue remaining entities if they are
+ * about to stop receiving service, or reposition them if this
+ * is not the case.
+ */
+ entity = parent;
+ for_each_entity(entity) {
+ /*
+ * Invoke __bfq_requeue_entity on entity, even if
+ * already active, to requeue/reposition it in the
+ * active tree (because sd->next_in_service has
+ * changed)
+ */
+ __bfq_requeue_entity(entity);
+
+ sd = entity->sched_data;
+ if (!bfq_update_next_in_service(sd, entity) &&
+ !expiration)
+ /*
+ * next_in_service unchanged or not causing
+ * any change in entity->parent->sd, and no
+ * requeueing needed for expiration: stop
+ * here.
+ */
+ break;
+ }
+}
+
+/**
+ * bfq_calc_vtime_jump - compute the value to which the vtime should jump,
+ * if needed, to have at least one entity eligible.
+ * @st: the service tree to act upon.
+ *
+ * Assumes that st is not empty.
+ */
+static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
+{
+ struct bfq_entity *root_entity = bfq_root_active_entity(&st->active);
+
+ if (bfq_gt(root_entity->min_start, st->vtime))
+ return root_entity->min_start;
+
+ return st->vtime;
+}
+
+static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value)
+{
+ if (new_value > st->vtime) {
+ st->vtime = new_value;
+ bfq_forget_idle(st);
+ }
+}
+
+/**
+ * bfq_first_active_entity - find the eligible entity with
+ * the smallest finish time
+ * @st: the service tree to select from.
+ * @vtime: the system virtual to use as a reference for eligibility
+ *
+ * This function searches the first schedulable entity, starting from the
+ * root of the tree and going on the left every time on this side there is
+ * a subtree with at least one eligible (start >= vtime) entity. The path on
+ * the right is followed only if a) the left subtree contains no eligible
+ * entities and b) no eligible entity has been found yet.
+ */
+static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st,
+ u64 vtime)
+{
+ struct bfq_entity *entry, *first = NULL;
+ struct rb_node *node = st->active.rb_node;
+
+ while (node) {
+ entry = rb_entry(node, struct bfq_entity, rb_node);
+left:
+ if (!bfq_gt(entry->start, vtime))
+ first = entry;
+
+ if (node->rb_left) {
+ entry = rb_entry(node->rb_left,
+ struct bfq_entity, rb_node);
+ if (!bfq_gt(entry->min_start, vtime)) {
+ node = node->rb_left;
+ goto left;
+ }
+ }
+ if (first)
+ break;
+ node = node->rb_right;
+ }
+
+ return first;
+}
+
+/**
+ * __bfq_lookup_next_entity - return the first eligible entity in @st.
+ * @st: the service tree.
+ *
+ * If there is no in-service entity for the sched_data st belongs to,
+ * then return the entity that will be set in service if:
+ * 1) the parent entity this st belongs to is set in service;
+ * 2) no entity belonging to such parent entity undergoes a state change
+ * that would influence the timestamps of the entity (e.g., becomes idle,
+ * becomes backlogged, changes its budget, ...).
+ *
+ * In this first case, update the virtual time in @st too (see the
+ * comments on this update inside the function).
+ *
+ * In constrast, if there is an in-service entity, then return the
+ * entity that would be set in service if not only the above
+ * conditions, but also the next one held true: the currently
+ * in-service entity, on expiration,
+ * 1) gets a finish time equal to the current one, or
+ * 2) is not eligible any more, or
+ * 3) is idle.
+ */
+static struct bfq_entity *
+__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service)
+{
+ struct bfq_entity *entity;
+ u64 new_vtime;
+
+ if (RB_EMPTY_ROOT(&st->active))
+ return NULL;
+
+ /*
+ * Get the value of the system virtual time for which at
+ * least one entity is eligible.
+ */
+ new_vtime = bfq_calc_vtime_jump(st);
+
+ /*
+ * If there is no in-service entity for the sched_data this
+ * active tree belongs to, then push the system virtual time
+ * up to the value that guarantees that at least one entity is
+ * eligible. If, instead, there is an in-service entity, then
+ * do not make any such update, because there is already an
+ * eligible entity, namely the in-service one (even if the
+ * entity is not on st, because it was extracted when set in
+ * service).
+ */
+ if (!in_service)
+ bfq_update_vtime(st, new_vtime);
+
+ entity = bfq_first_active_entity(st, new_vtime);
+
+ return entity;
+}
+
+/**
+ * bfq_lookup_next_entity - return the first eligible entity in @sd.
+ * @sd: the sched_data.
+ *
+ * This function is invoked when there has been a change in the trees
+ * for sd, and we need know what is the new next entity after this
+ * change.
+ */
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd)
+{
+ struct bfq_service_tree *st = sd->service_tree;
+ struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);
+ struct bfq_entity *entity = NULL;
+ int class_idx = 0;
+
+ /*
+ * Choose from idle class, if needed to guarantee a minimum
+ * bandwidth to this class (and if there is some active entity
+ * in idle class). This should also mitigate
+ * priority-inversion problems in case a low priority task is
+ * holding file system resources.
+ */
+ if (time_is_before_jiffies(sd->bfq_class_idle_last_service +
+ BFQ_CL_IDLE_TIMEOUT)) {
+ if (!RB_EMPTY_ROOT(&idle_class_st->active))
+ class_idx = BFQ_IOPRIO_CLASSES - 1;
+ /* About to be served if backlogged, or not yet backlogged */
+ sd->bfq_class_idle_last_service = jiffies;
+ }
+
+ /*
+ * Find the next entity to serve for the highest-priority
+ * class, unless the idle class needs to be served.
+ */
+ for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) {
+ entity = __bfq_lookup_next_entity(st + class_idx,
+ sd->in_service_entity);
+
+ if (entity)
+ break;
+ }
+
+ if (!entity)
+ return NULL;
+
+ return entity;
+}
+
+bool next_queue_may_preempt(struct bfq_data *bfqd)
+{
+ struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
+
+ return sd->next_in_service != sd->in_service_entity;
+}
+
+/*
+ * Get next queue for service.
+ */
+struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
+{
+ struct bfq_entity *entity = NULL;
+ struct bfq_sched_data *sd;
+ struct bfq_queue *bfqq;
+
+ if (bfqd->busy_queues == 0)
+ return NULL;
+
+ /*
+ * Traverse the path from the root to the leaf entity to
+ * serve. Set in service all the entities visited along the
+ * way.
+ */
+ sd = &bfqd->root_group->sched_data;
+ for (; sd ; sd = entity->my_sched_data) {
+ /*
+ * WARNING. We are about to set the in-service entity
+ * to sd->next_in_service, i.e., to the (cached) value
+ * returned by bfq_lookup_next_entity(sd) the last
+ * time it was invoked, i.e., the last time when the
+ * service order in sd changed as a consequence of the
+ * activation or deactivation of an entity. In this
+ * respect, if we execute bfq_lookup_next_entity(sd)
+ * in this very moment, it may, although with low
+ * probability, yield a different entity than that
+ * pointed to by sd->next_in_service. This rare event
+ * happens in case there was no CLASS_IDLE entity to
+ * serve for sd when bfq_lookup_next_entity(sd) was
+ * invoked for the last time, while there is now one
+ * such entity.
+ *
+ * If the above event happens, then the scheduling of
+ * such entity in CLASS_IDLE is postponed until the
+ * service of the sd->next_in_service entity
+ * finishes. In fact, when the latter is expired,
+ * bfq_lookup_next_entity(sd) gets called again,
+ * exactly to update sd->next_in_service.
+ */
+
+ /* Make next_in_service entity become in_service_entity */
+ entity = sd->next_in_service;
+ sd->in_service_entity = entity;
+
+ /*
+ * Reset the accumulator of the amount of service that
+ * the entity is about to receive.
+ */
+ entity->service = 0;
+
+ /*
+ * If entity is no longer a candidate for next
+ * service, then we extract it from its active tree,
+ * for the following reason. To further boost the
+ * throughput in some special case, BFQ needs to know
+ * which is the next candidate entity to serve, while
+ * there is already an entity in service. In this
+ * respect, to make it easy to compute/update the next
+ * candidate entity to serve after the current
+ * candidate has been set in service, there is a case
+ * where it is necessary to extract the current
+ * candidate from its service tree. Such a case is
+ * when the entity just set in service cannot be also
+ * a candidate for next service. Details about when
+ * this conditions holds are reported in the comments
+ * on the function bfq_no_longer_next_in_service()
+ * invoked below.
+ */
+ if (bfq_no_longer_next_in_service(entity))
+ bfq_active_extract(bfq_entity_service_tree(entity),
+ entity);
+
+ /*
+ * For the same reason why we may have just extracted
+ * entity from its active tree, we may need to update
+ * next_in_service for the sched_data of entity too,
+ * regardless of whether entity has been extracted.
+ * In fact, even if entity has not been extracted, a
+ * descendant entity may get extracted. Such an event
+ * would cause a change in next_in_service for the
+ * level of the descendant entity, and thus possibly
+ * back to upper levels.
+ *
+ * We cannot perform the resulting needed update
+ * before the end of this loop, because, to know which
+ * is the correct next-to-serve candidate entity for
+ * each level, we need first to find the leaf entity
+ * to set in service. In fact, only after we know
+ * which is the next-to-serve leaf entity, we can
+ * discover whether the parent entity of the leaf
+ * entity becomes the next-to-serve, and so on.
+ */
+
+ }
+
+ bfqq = bfq_entity_to_bfqq(entity);
+
+ /*
+ * We can finally update all next-to-serve entities along the
+ * path from the leaf entity just set in service to the root.
+ */
+ for_each_entity(entity) {
+ struct bfq_sched_data *sd = entity->sched_data;
+
+ if (!bfq_update_next_in_service(sd, NULL))
+ break;
+ }
+
+ return bfqq;
+}
+
+void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
+{
+ struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue;
+ struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;
+ struct bfq_entity *entity = in_serv_entity;
+
+ bfq_clear_bfqq_wait_request(in_serv_bfqq);
+ hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
+ bfqd->in_service_queue = NULL;
+
+ /*
+ * When this function is called, all in-service entities have
+ * been properly deactivated or requeued, so we can safely
+ * execute the final step: reset in_service_entity along the
+ * path from entity to the root.
+ */
+ for_each_entity(entity)
+ entity->sched_data->in_service_entity = NULL;
+
+ /*
+ * in_serv_entity is no longer in service, so, if it is in no
+ * service tree either, then release the service reference to
+ * the queue it represents (taken with bfq_get_entity).
+ */
+ if (!in_serv_entity->on_st)
+ bfq_put_queue(in_serv_bfqq);
+}
+
+void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool ins_into_idle_tree, bool expiration)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_deactivate_entity(entity, ins_into_idle_tree, expiration);
+}
+
+void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq),
+ false);
+ bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
+}
+
+void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_activate_requeue_entity(entity, false,
+ bfqq == bfqd->in_service_queue);
+}
+
+/*
+ * Called when the bfqq no longer has requests pending, remove it from
+ * the service tree. As a special case, it can be invoked during an
+ * expiration.
+ */
+void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool expiration)
+{
+ bfq_log_bfqq(bfqd, bfqq, "del from busy");
+
+ bfq_clear_bfqq_busy(bfqq);
+
+ bfqd->busy_queues--;
+
+ if (!bfqq->dispatched)
+ bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+
+ if (bfqq->wr_coeff > 1)
+ bfqd->wr_busy_queues--;
+
+ bfqg_stats_update_dequeue(bfqq_group(bfqq));
+
+ bfq_deactivate_bfqq(bfqd, bfqq, true, expiration);
+}
+
+/*
+ * Called when an inactive queue receives a new request.
+ */
+void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqd, bfqq, "add to busy");
+
+ bfq_activate_bfqq(bfqd, bfqq);
+
+ bfq_mark_bfqq_busy(bfqq);
+ bfqd->busy_queues++;
+
+ if (!bfqq->dispatched)
+ if (bfqq->wr_coeff == 1)
+ bfq_weights_tree_add(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+
+ if (bfqq->wr_coeff > 1)
+ bfqd->wr_busy_queues++;
+}
diff --git a/block/bio.c b/block/bio.c
index e75878f8b14a..888e7801c638 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -30,6 +30,7 @@
#include <linux/cgroup.h>
#include <trace/events/block.h>
+#include "blk.h"
/*
* Test patch to inline a certain number of bi_io_vec's inside the bio
@@ -427,7 +428,8 @@ static void punt_bios_to_rescuer(struct bio_set *bs)
* RETURNS:
* Pointer to new bio on success, NULL on failure.
*/
-struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
+struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
+ struct bio_set *bs)
{
gfp_t saved_gfp = gfp_mask;
unsigned front_pad;
@@ -631,20 +633,21 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
}
EXPORT_SYMBOL(bio_clone_fast);
-static struct bio *__bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
- struct bio_set *bs, int offset,
- int size)
+/**
+ * bio_clone_bioset - clone a bio
+ * @bio_src: bio to clone
+ * @gfp_mask: allocation priority
+ * @bs: bio_set to allocate from
+ *
+ * Clone bio. Caller will own the returned bio, but not the actual data it
+ * points to. Reference count of returned bio will be one.
+ */
+struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
+ struct bio_set *bs)
{
struct bvec_iter iter;
struct bio_vec bv;
struct bio *bio;
- struct bvec_iter iter_src = bio_src->bi_iter;
-
- /* for supporting partial clone */
- if (offset || size != bio_src->bi_iter.bi_size) {
- bio_advance_iter(bio_src, &iter_src, offset);
- iter_src.bi_size = size;
- }
/*
* Pre immutable biovecs, __bio_clone() used to just do a memcpy from
@@ -668,8 +671,7 @@ static struct bio *__bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
* __bio_clone_fast() anyways.
*/
- bio = bio_alloc_bioset(gfp_mask, __bio_segments(bio_src,
- &iter_src), bs);
+ bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
if (!bio)
return NULL;
bio->bi_bdev = bio_src->bi_bdev;
@@ -686,7 +688,7 @@ static struct bio *__bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
break;
default:
- __bio_for_each_segment(bv, bio_src, iter, iter_src)
+ bio_for_each_segment(bv, bio_src, iter)
bio->bi_io_vec[bio->bi_vcnt++] = bv;
break;
}
@@ -705,44 +707,9 @@ static struct bio *__bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
return bio;
}
-
-/**
- * bio_clone_bioset - clone a bio
- * @bio_src: bio to clone
- * @gfp_mask: allocation priority
- * @bs: bio_set to allocate from
- *
- * Clone bio. Caller will own the returned bio, but not the actual data it
- * points to. Reference count of returned bio will be one.
- */
-struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
- struct bio_set *bs)
-{
- return __bio_clone_bioset(bio_src, gfp_mask, bs, 0,
- bio_src->bi_iter.bi_size);
-}
EXPORT_SYMBOL(bio_clone_bioset);
/**
- * bio_clone_bioset_partial - clone a partial bio
- * @bio_src: bio to clone
- * @gfp_mask: allocation priority
- * @bs: bio_set to allocate from
- * @offset: cloned starting from the offset
- * @size: size for the cloned bio
- *
- * Clone bio. Caller will own the returned bio, but not the actual data it
- * points to. Reference count of returned bio will be one.
- */
-struct bio *bio_clone_bioset_partial(struct bio *bio_src, gfp_t gfp_mask,
- struct bio_set *bs, int offset,
- int size)
-{
- return __bio_clone_bioset(bio_src, gfp_mask, bs, offset, size);
-}
-EXPORT_SYMBOL(bio_clone_bioset_partial);
-
-/**
* bio_add_pc_page - attempt to add page to bio
* @q: the target queue
* @bio: destination bio
@@ -1824,6 +1791,11 @@ static inline bool bio_remaining_done(struct bio *bio)
* bio_endio() will end I/O on the whole bio. bio_endio() is the preferred
* way to end I/O on a bio. No one should call bi_end_io() directly on a
* bio unless they own it and thus know that it has an end_io function.
+ *
+ * bio_endio() can be called several times on a bio that has been chained
+ * using bio_chain(). The ->bi_end_io() function will only be called the
+ * last time. At this point the BLK_TA_COMPLETE tracing event will be
+ * generated if BIO_TRACE_COMPLETION is set.
**/
void bio_endio(struct bio *bio)
{
@@ -1844,6 +1816,13 @@ again:
goto again;
}
+ if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
+ trace_block_bio_complete(bdev_get_queue(bio->bi_bdev),
+ bio, bio->bi_error);
+ bio_clear_flag(bio, BIO_TRACE_COMPLETION);
+ }
+
+ blk_throtl_bio_endio(bio);
if (bio->bi_end_io)
bio->bi_end_io(bio);
}
@@ -1882,6 +1861,9 @@ struct bio *bio_split(struct bio *bio, int sectors,
bio_advance(bio, split->bi_iter.bi_size);
+ if (bio_flagged(bio, BIO_TRACE_COMPLETION))
+ bio_set_flag(bio, BIO_TRACE_COMPLETION);
+
return split;
}
EXPORT_SYMBOL(bio_split);
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index bbe7ee00bd3d..7c2947128f58 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -772,6 +772,27 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
}
EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
+/* Performs queue bypass and policy enabled checks then looks up blkg. */
+static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg,
+ const struct blkcg_policy *pol,
+ struct request_queue *q)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ lockdep_assert_held(q->queue_lock);
+
+ if (!blkcg_policy_enabled(q, pol))
+ return ERR_PTR(-EOPNOTSUPP);
+
+ /*
+ * This could be the first entry point of blkcg implementation and
+ * we shouldn't allow anything to go through for a bypassing queue.
+ */
+ if (unlikely(blk_queue_bypass(q)))
+ return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
+
+ return __blkg_lookup(blkcg, q, true /* update_hint */);
+}
+
/**
* blkg_conf_prep - parse and prepare for per-blkg config update
* @blkcg: target block cgroup
@@ -789,6 +810,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
__acquires(rcu) __acquires(disk->queue->queue_lock)
{
struct gendisk *disk;
+ struct request_queue *q;
struct blkcg_gq *blkg;
struct module *owner;
unsigned int major, minor;
@@ -807,44 +829,95 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
if (!disk)
return -ENODEV;
if (part) {
- owner = disk->fops->owner;
- put_disk(disk);
- module_put(owner);
- return -ENODEV;
+ ret = -ENODEV;
+ goto fail;
}
- rcu_read_lock();
- spin_lock_irq(disk->queue->queue_lock);
+ q = disk->queue;
- if (blkcg_policy_enabled(disk->queue, pol))
- blkg = blkg_lookup_create(blkcg, disk->queue);
- else
- blkg = ERR_PTR(-EOPNOTSUPP);
+ rcu_read_lock();
+ spin_lock_irq(q->queue_lock);
+ blkg = blkg_lookup_check(blkcg, pol, q);
if (IS_ERR(blkg)) {
ret = PTR_ERR(blkg);
+ goto fail_unlock;
+ }
+
+ if (blkg)
+ goto success;
+
+ /*
+ * Create blkgs walking down from blkcg_root to @blkcg, so that all
+ * non-root blkgs have access to their parents.
+ */
+ while (true) {
+ struct blkcg *pos = blkcg;
+ struct blkcg *parent;
+ struct blkcg_gq *new_blkg;
+
+ parent = blkcg_parent(blkcg);
+ while (parent && !__blkg_lookup(parent, q, false)) {
+ pos = parent;
+ parent = blkcg_parent(parent);
+ }
+
+ /* Drop locks to do new blkg allocation with GFP_KERNEL. */
+ spin_unlock_irq(q->queue_lock);
rcu_read_unlock();
- spin_unlock_irq(disk->queue->queue_lock);
- owner = disk->fops->owner;
- put_disk(disk);
- module_put(owner);
- /*
- * If queue was bypassing, we should retry. Do so after a
- * short msleep(). It isn't strictly necessary but queue
- * can be bypassing for some time and it's always nice to
- * avoid busy looping.
- */
- if (ret == -EBUSY) {
- msleep(10);
- ret = restart_syscall();
+
+ new_blkg = blkg_alloc(pos, q, GFP_KERNEL);
+ if (unlikely(!new_blkg)) {
+ ret = -ENOMEM;
+ goto fail;
}
- return ret;
- }
+ rcu_read_lock();
+ spin_lock_irq(q->queue_lock);
+
+ blkg = blkg_lookup_check(pos, pol, q);
+ if (IS_ERR(blkg)) {
+ ret = PTR_ERR(blkg);
+ goto fail_unlock;
+ }
+
+ if (blkg) {
+ blkg_free(new_blkg);
+ } else {
+ blkg = blkg_create(pos, q, new_blkg);
+ if (unlikely(IS_ERR(blkg))) {
+ ret = PTR_ERR(blkg);
+ goto fail_unlock;
+ }
+ }
+
+ if (pos == blkcg)
+ goto success;
+ }
+success:
ctx->disk = disk;
ctx->blkg = blkg;
ctx->body = body;
return 0;
+
+fail_unlock:
+ spin_unlock_irq(q->queue_lock);
+ rcu_read_unlock();
+fail:
+ owner = disk->fops->owner;
+ put_disk(disk);
+ module_put(owner);
+ /*
+ * If queue was bypassing, we should retry. Do so after a
+ * short msleep(). It isn't strictly necessary but queue
+ * can be bypassing for some time and it's always nice to
+ * avoid busy looping.
+ */
+ if (ret == -EBUSY) {
+ msleep(10);
+ ret = restart_syscall();
+ }
+ return ret;
}
EXPORT_SYMBOL_GPL(blkg_conf_prep);
diff --git a/block/blk-core.c b/block/blk-core.c
index d772c221cc17..24886b69690f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -268,10 +268,8 @@ void blk_sync_queue(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
- queue_for_each_hw_ctx(q, hctx, i) {
- cancel_work_sync(&hctx->run_work);
- cancel_delayed_work_sync(&hctx->delay_work);
- }
+ queue_for_each_hw_ctx(q, hctx, i)
+ cancel_delayed_work_sync(&hctx->run_work);
} else {
cancel_delayed_work_sync(&q->delay_work);
}
@@ -500,6 +498,13 @@ void blk_set_queue_dying(struct request_queue *q)
queue_flag_set(QUEUE_FLAG_DYING, q);
spin_unlock_irq(q->queue_lock);
+ /*
+ * When queue DYING flag is set, we need to block new req
+ * entering queue, so we call blk_freeze_queue_start() to
+ * prevent I/O from crossing blk_queue_enter().
+ */
+ blk_freeze_queue_start(q);
+
if (q->mq_ops)
blk_mq_wake_waiters(q);
else {
@@ -556,9 +561,13 @@ void blk_cleanup_queue(struct request_queue *q)
* prevent that q->request_fn() gets invoked after draining finished.
*/
blk_freeze_queue(q);
- spin_lock_irq(lock);
- if (!q->mq_ops)
+ if (!q->mq_ops) {
+ spin_lock_irq(lock);
__blk_drain_queue(q, true);
+ } else {
+ blk_mq_debugfs_unregister_mq(q);
+ spin_lock_irq(lock);
+ }
queue_flag_set(QUEUE_FLAG_DEAD, q);
spin_unlock_irq(lock);
@@ -669,6 +678,15 @@ int blk_queue_enter(struct request_queue *q, bool nowait)
if (nowait)
return -EBUSY;
+ /*
+ * read pair of barrier in blk_freeze_queue_start(),
+ * we need to order reading __PERCPU_REF_DEAD flag of
+ * .q_usage_counter and reading .mq_freeze_depth or
+ * queue dying flag, otherwise the following wait may
+ * never return if the two reads are reordered.
+ */
+ smp_rmb();
+
ret = wait_event_interruptible(q->mq_freeze_wq,
!atomic_read(&q->mq_freeze_depth) ||
blk_queue_dying(q));
@@ -720,6 +738,10 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
if (!q->backing_dev_info)
goto fail_split;
+ q->stats = blk_alloc_queue_stats();
+ if (!q->stats)
+ goto fail_stats;
+
q->backing_dev_info->ra_pages =
(VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
@@ -776,6 +798,8 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
fail_ref:
percpu_ref_exit(&q->q_usage_counter);
fail_bdi:
+ blk_free_queue_stats(q->stats);
+fail_stats:
bdi_put(q->backing_dev_info);
fail_split:
bioset_free(q->bio_split);
@@ -889,7 +913,6 @@ out_exit_flush_rq:
q->exit_rq_fn(q, q->fq->flush_rq);
out_free_flush_queue:
blk_free_flush_queue(q->fq);
- wbt_exit(q);
return -ENOMEM;
}
EXPORT_SYMBOL(blk_init_allocated_queue);
@@ -1128,7 +1151,6 @@ static struct request *__get_request(struct request_list *rl, unsigned int op,
blk_rq_init(q, rq);
blk_rq_set_rl(rq, rl);
- blk_rq_set_prio(rq, ioc);
rq->cmd_flags = op;
rq->rq_flags = rq_flags;
@@ -1608,17 +1630,23 @@ out:
return ret;
}
-void init_request_from_bio(struct request *req, struct bio *bio)
+void blk_init_request_from_bio(struct request *req, struct bio *bio)
{
+ struct io_context *ioc = rq_ioc(bio);
+
if (bio->bi_opf & REQ_RAHEAD)
req->cmd_flags |= REQ_FAILFAST_MASK;
- req->errors = 0;
req->__sector = bio->bi_iter.bi_sector;
if (ioprio_valid(bio_prio(bio)))
req->ioprio = bio_prio(bio);
+ else if (ioc)
+ req->ioprio = ioc->ioprio;
+ else
+ req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
blk_rq_bio_prep(req->q, req, bio);
}
+EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
{
@@ -1709,7 +1737,7 @@ get_rq:
* We don't worry about that case for efficiency. It won't happen
* often, and the elevators are able to handle it.
*/
- init_request_from_bio(req, bio);
+ blk_init_request_from_bio(req, bio);
if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
req->cpu = raw_smp_processor_id();
@@ -1936,7 +1964,13 @@ generic_make_request_checks(struct bio *bio)
if (!blkcg_bio_issue_check(q, bio))
return false;
- trace_block_bio_queue(q, bio);
+ if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
+ trace_block_bio_queue(q, bio);
+ /* Now that enqueuing has been traced, we need to trace
+ * completion as well.
+ */
+ bio_set_flag(bio, BIO_TRACE_COMPLETION);
+ }
return true;
not_supported:
@@ -2478,7 +2512,7 @@ void blk_start_request(struct request *req)
blk_dequeue_request(req);
if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) {
- blk_stat_set_issue_time(&req->issue_stat);
+ blk_stat_set_issue(&req->issue_stat, blk_rq_sectors(req));
req->rq_flags |= RQF_STATS;
wbt_issue(req->q->rq_wb, &req->issue_stat);
}
@@ -2540,22 +2574,11 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
{
int total_bytes;
- trace_block_rq_complete(req->q, req, nr_bytes);
+ trace_block_rq_complete(req, error, nr_bytes);
if (!req->bio)
return false;
- /*
- * For fs requests, rq is just carrier of independent bio's
- * and each partial completion should be handled separately.
- * Reset per-request error on each partial completion.
- *
- * TODO: tj: This is too subtle. It would be better to let
- * low level drivers do what they see fit.
- */
- if (!blk_rq_is_passthrough(req))
- req->errors = 0;
-
if (error && !blk_rq_is_passthrough(req) &&
!(req->rq_flags & RQF_QUIET)) {
char *error_type;
@@ -2601,6 +2624,8 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
if (bio_bytes == bio->bi_iter.bi_size)
req->bio = bio->bi_next;
+ /* Completion has already been traced */
+ bio_clear_flag(bio, BIO_TRACE_COMPLETION);
req_bio_endio(req, bio, bio_bytes, error);
total_bytes += bio_bytes;
@@ -2699,7 +2724,7 @@ void blk_finish_request(struct request *req, int error)
struct request_queue *q = req->q;
if (req->rq_flags & RQF_STATS)
- blk_stat_add(&q->rq_stats[rq_data_dir(req)], req);
+ blk_stat_add(req);
if (req->rq_flags & RQF_QUEUED)
blk_queue_end_tag(q, req);
@@ -2776,7 +2801,7 @@ static bool blk_end_bidi_request(struct request *rq, int error,
* %false - we are done with this request
* %true - still buffers pending for this request
**/
-bool __blk_end_bidi_request(struct request *rq, int error,
+static bool __blk_end_bidi_request(struct request *rq, int error,
unsigned int nr_bytes, unsigned int bidi_bytes)
{
if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
@@ -2829,43 +2854,6 @@ void blk_end_request_all(struct request *rq, int error)
EXPORT_SYMBOL(blk_end_request_all);
/**
- * blk_end_request_cur - Helper function to finish the current request chunk.
- * @rq: the request to finish the current chunk for
- * @error: %0 for success, < %0 for error
- *
- * Description:
- * Complete the current consecutively mapped chunk from @rq.
- *
- * Return:
- * %false - we are done with this request
- * %true - still buffers pending for this request
- */
-bool blk_end_request_cur(struct request *rq, int error)
-{
- return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
-}
-EXPORT_SYMBOL(blk_end_request_cur);
-
-/**
- * blk_end_request_err - Finish a request till the next failure boundary.
- * @rq: the request to finish till the next failure boundary for
- * @error: must be negative errno
- *
- * Description:
- * Complete @rq till the next failure boundary.
- *
- * Return:
- * %false - we are done with this request
- * %true - still buffers pending for this request
- */
-bool blk_end_request_err(struct request *rq, int error)
-{
- WARN_ON(error >= 0);
- return blk_end_request(rq, error, blk_rq_err_bytes(rq));
-}
-EXPORT_SYMBOL_GPL(blk_end_request_err);
-
-/**
* __blk_end_request - Helper function for drivers to complete the request.
* @rq: the request being processed
* @error: %0 for success, < %0 for error
@@ -2924,26 +2912,6 @@ bool __blk_end_request_cur(struct request *rq, int error)
}
EXPORT_SYMBOL(__blk_end_request_cur);
-/**
- * __blk_end_request_err - Finish a request till the next failure boundary.
- * @rq: the request to finish till the next failure boundary for
- * @error: must be negative errno
- *
- * Description:
- * Complete @rq till the next failure boundary. Must be called
- * with queue lock held.
- *
- * Return:
- * %false - we are done with this request
- * %true - still buffers pending for this request
- */
-bool __blk_end_request_err(struct request *rq, int error)
-{
- WARN_ON(error >= 0);
- return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
-}
-EXPORT_SYMBOL_GPL(__blk_end_request_err);
-
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
struct bio *bio)
{
@@ -3106,6 +3074,13 @@ int kblockd_schedule_work_on(int cpu, struct work_struct *work)
}
EXPORT_SYMBOL(kblockd_schedule_work_on);
+int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
+ unsigned long delay)
+{
+ return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
+}
+EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
+
int kblockd_schedule_delayed_work(struct delayed_work *dwork,
unsigned long delay)
{
diff --git a/block/blk-exec.c b/block/blk-exec.c
index 8cd0e9bc8dc8..a9451e3b8587 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -69,8 +69,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
if (unlikely(blk_queue_dying(q))) {
rq->rq_flags |= RQF_QUIET;
- rq->errors = -ENXIO;
- __blk_end_request_all(rq, rq->errors);
+ __blk_end_request_all(rq, -ENXIO);
spin_unlock_irq(q->queue_lock);
return;
}
@@ -92,11 +91,10 @@ EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
* Insert a fully prepared request at the back of the I/O scheduler queue
* for execution and wait for completion.
*/
-int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
+void blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
struct request *rq, int at_head)
{
DECLARE_COMPLETION_ONSTACK(wait);
- int err = 0;
unsigned long hang_check;
rq->end_io_data = &wait;
@@ -108,10 +106,5 @@ int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
else
wait_for_completion_io(&wait);
-
- if (rq->errors)
- err = -EIO;
-
- return err;
}
EXPORT_SYMBOL(blk_execute_rq);
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 0d5a9c1da1fc..c4e0880b54bb 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -447,7 +447,7 @@ void blk_insert_flush(struct request *rq)
if (q->mq_ops)
blk_mq_end_request(rq, 0);
else
- __blk_end_bidi_request(rq, 0, 0, 0);
+ __blk_end_request(rq, 0, 0);
return;
}
@@ -497,8 +497,7 @@ void blk_insert_flush(struct request *rq)
* Description:
* Issue a flush for the block device in question. Caller can supply
* room for storing the error offset in case of a flush error, if they
- * wish to. If WAIT flag is not passed then caller may check only what
- * request was pushed in some internal queue for later handling.
+ * wish to.
*/
int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
sector_t *error_sector)
diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index 9f0ff5ba4f84..0f891a9aff4d 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -389,7 +389,7 @@ static int blk_integrity_nop_fn(struct blk_integrity_iter *iter)
return 0;
}
-static struct blk_integrity_profile nop_profile = {
+static const struct blk_integrity_profile nop_profile = {
.name = "nop",
.generate_fn = blk_integrity_nop_fn,
.verify_fn = blk_integrity_nop_fn,
@@ -412,12 +412,13 @@ void blk_integrity_register(struct gendisk *disk, struct blk_integrity *template
bi->flags = BLK_INTEGRITY_VERIFY | BLK_INTEGRITY_GENERATE |
template->flags;
- bi->interval_exp = ilog2(queue_logical_block_size(disk->queue));
+ bi->interval_exp = template->interval_exp ? :
+ ilog2(queue_logical_block_size(disk->queue));
bi->profile = template->profile ? template->profile : &nop_profile;
bi->tuple_size = template->tuple_size;
bi->tag_size = template->tag_size;
- blk_integrity_revalidate(disk);
+ disk->queue->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
}
EXPORT_SYMBOL(blk_integrity_register);
@@ -430,26 +431,11 @@ EXPORT_SYMBOL(blk_integrity_register);
*/
void blk_integrity_unregister(struct gendisk *disk)
{
- blk_integrity_revalidate(disk);
+ disk->queue->backing_dev_info->capabilities &= ~BDI_CAP_STABLE_WRITES;
memset(&disk->queue->integrity, 0, sizeof(struct blk_integrity));
}
EXPORT_SYMBOL(blk_integrity_unregister);
-void blk_integrity_revalidate(struct gendisk *disk)
-{
- struct blk_integrity *bi = &disk->queue->integrity;
-
- if (!(disk->flags & GENHD_FL_UP))
- return;
-
- if (bi->profile)
- disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_STABLE_WRITES;
- else
- disk->queue->backing_dev_info->capabilities &=
- ~BDI_CAP_STABLE_WRITES;
-}
-
void blk_integrity_add(struct gendisk *disk)
{
if (kobject_init_and_add(&disk->integrity_kobj, &integrity_ktype,
diff --git a/block/blk-lib.c b/block/blk-lib.c
index ed1e78e24db0..e8caecd71688 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -37,17 +37,12 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
return -ENXIO;
if (flags & BLKDEV_DISCARD_SECURE) {
- if (flags & BLKDEV_DISCARD_ZERO)
- return -EOPNOTSUPP;
if (!blk_queue_secure_erase(q))
return -EOPNOTSUPP;
op = REQ_OP_SECURE_ERASE;
} else {
if (!blk_queue_discard(q))
return -EOPNOTSUPP;
- if ((flags & BLKDEV_DISCARD_ZERO) &&
- !q->limits.discard_zeroes_data)
- return -EOPNOTSUPP;
op = REQ_OP_DISCARD;
}
@@ -109,7 +104,7 @@ EXPORT_SYMBOL(__blkdev_issue_discard);
* @sector: start sector
* @nr_sects: number of sectors to discard
* @gfp_mask: memory allocation flags (for bio_alloc)
- * @flags: BLKDEV_IFL_* flags to control behaviour
+ * @flags: BLKDEV_DISCARD_* flags to control behaviour
*
* Description:
* Issue a discard request for the sectors in question.
@@ -126,7 +121,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
&bio);
if (!ret && bio) {
ret = submit_bio_wait(bio);
- if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO))
+ if (ret == -EOPNOTSUPP)
ret = 0;
bio_put(bio);
}
@@ -226,20 +221,9 @@ int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
}
EXPORT_SYMBOL(blkdev_issue_write_same);
-/**
- * __blkdev_issue_write_zeroes - generate number of bios with WRITE ZEROES
- * @bdev: blockdev to issue
- * @sector: start sector
- * @nr_sects: number of sectors to write
- * @gfp_mask: memory allocation flags (for bio_alloc)
- * @biop: pointer to anchor bio
- *
- * Description:
- * Generate and issue number of bios(REQ_OP_WRITE_ZEROES) with zerofiled pages.
- */
static int __blkdev_issue_write_zeroes(struct block_device *bdev,
sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
- struct bio **biop)
+ struct bio **biop, unsigned flags)
{
struct bio *bio = *biop;
unsigned int max_write_zeroes_sectors;
@@ -258,7 +242,9 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
bio = next_bio(bio, 0, gfp_mask);
bio->bi_iter.bi_sector = sector;
bio->bi_bdev = bdev;
- bio_set_op_attrs(bio, REQ_OP_WRITE_ZEROES, 0);
+ bio->bi_opf = REQ_OP_WRITE_ZEROES;
+ if (flags & BLKDEV_ZERO_NOUNMAP)
+ bio->bi_opf |= REQ_NOUNMAP;
if (nr_sects > max_write_zeroes_sectors) {
bio->bi_iter.bi_size = max_write_zeroes_sectors << 9;
@@ -282,14 +268,27 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
* @nr_sects: number of sectors to write
* @gfp_mask: memory allocation flags (for bio_alloc)
* @biop: pointer to anchor bio
- * @discard: discard flag
+ * @flags: controls detailed behavior
*
* Description:
- * Generate and issue number of bios with zerofiled pages.
+ * Zero-fill a block range, either using hardware offload or by explicitly
+ * writing zeroes to the device.
+ *
+ * Note that this function may fail with -EOPNOTSUPP if the driver signals
+ * zeroing offload support, but the device fails to process the command (for
+ * some devices there is no non-destructive way to verify whether this
+ * operation is actually supported). In this case the caller should call
+ * retry the call to blkdev_issue_zeroout() and the fallback path will be used.
+ *
+ * If a device is using logical block provisioning, the underlying space will
+ * not be released if %flags contains BLKDEV_ZERO_NOUNMAP.
+ *
+ * If %flags contains BLKDEV_ZERO_NOFALLBACK, the function will return
+ * -EOPNOTSUPP if no explicit hardware offload for zeroing is provided.
*/
int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, struct bio **biop,
- bool discard)
+ unsigned flags)
{
int ret;
int bi_size = 0;
@@ -302,8 +301,8 @@ int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
return -EINVAL;
ret = __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
- biop);
- if (ret == 0 || (ret && ret != -EOPNOTSUPP))
+ biop, flags);
+ if (ret != -EOPNOTSUPP || (flags & BLKDEV_ZERO_NOFALLBACK))
goto out;
ret = 0;
@@ -337,40 +336,23 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout);
* @sector: start sector
* @nr_sects: number of sectors to write
* @gfp_mask: memory allocation flags (for bio_alloc)
- * @discard: whether to discard the block range
+ * @flags: controls detailed behavior
*
* Description:
- * Zero-fill a block range. If the discard flag is set and the block
- * device guarantees that subsequent READ operations to the block range
- * in question will return zeroes, the blocks will be discarded. Should
- * the discard request fail, if the discard flag is not set, or if
- * discard_zeroes_data is not supported, this function will resort to
- * zeroing the blocks manually, thus provisioning (allocating,
- * anchoring) them. If the block device supports WRITE ZEROES or WRITE SAME
- * command(s), blkdev_issue_zeroout() will use it to optimize the process of
- * clearing the block range. Otherwise the zeroing will be performed
- * using regular WRITE calls.
+ * Zero-fill a block range, either using hardware offload or by explicitly
+ * writing zeroes to the device. See __blkdev_issue_zeroout() for the
+ * valid values for %flags.
*/
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
- sector_t nr_sects, gfp_t gfp_mask, bool discard)
+ sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
{
int ret;
struct bio *bio = NULL;
struct blk_plug plug;
- if (discard) {
- if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
- BLKDEV_DISCARD_ZERO))
- return 0;
- }
-
- if (!blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
- ZERO_PAGE(0)))
- return 0;
-
blk_start_plug(&plug);
ret = __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask,
- &bio, discard);
+ &bio, flags);
if (ret == 0 && bio) {
ret = submit_bio_wait(bio);
bio_put(bio);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 2afa262425d1..3990ae406341 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -54,6 +54,20 @@ static struct bio *blk_bio_discard_split(struct request_queue *q,
return bio_split(bio, split_sectors, GFP_NOIO, bs);
}
+static struct bio *blk_bio_write_zeroes_split(struct request_queue *q,
+ struct bio *bio, struct bio_set *bs, unsigned *nsegs)
+{
+ *nsegs = 1;
+
+ if (!q->limits.max_write_zeroes_sectors)
+ return NULL;
+
+ if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors)
+ return NULL;
+
+ return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs);
+}
+
static struct bio *blk_bio_write_same_split(struct request_queue *q,
struct bio *bio,
struct bio_set *bs,
@@ -200,8 +214,7 @@ void blk_queue_split(struct request_queue *q, struct bio **bio,
split = blk_bio_discard_split(q, *bio, bs, &nsegs);
break;
case REQ_OP_WRITE_ZEROES:
- split = NULL;
- nsegs = (*bio)->bi_phys_segments;
+ split = blk_bio_write_zeroes_split(q, *bio, bs, &nsegs);
break;
case REQ_OP_WRITE_SAME:
split = blk_bio_write_same_split(q, *bio, bs, &nsegs);
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index f6d917977b33..bcd2a7d4a3a5 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -43,11 +43,157 @@ static int blk_mq_debugfs_seq_open(struct inode *inode, struct file *file,
return ret;
}
+static int blk_flags_show(struct seq_file *m, const unsigned long flags,
+ const char *const *flag_name, int flag_name_count)
+{
+ bool sep = false;
+ int i;
+
+ for (i = 0; i < sizeof(flags) * BITS_PER_BYTE; i++) {
+ if (!(flags & BIT(i)))
+ continue;
+ if (sep)
+ seq_puts(m, " ");
+ sep = true;
+ if (i < flag_name_count && flag_name[i])
+ seq_puts(m, flag_name[i]);
+ else
+ seq_printf(m, "%d", i);
+ }
+ return 0;
+}
+
+static const char *const blk_queue_flag_name[] = {
+ [QUEUE_FLAG_QUEUED] = "QUEUED",
+ [QUEUE_FLAG_STOPPED] = "STOPPED",
+ [QUEUE_FLAG_SYNCFULL] = "SYNCFULL",
+ [QUEUE_FLAG_ASYNCFULL] = "ASYNCFULL",
+ [QUEUE_FLAG_DYING] = "DYING",
+ [QUEUE_FLAG_BYPASS] = "BYPASS",
+ [QUEUE_FLAG_BIDI] = "BIDI",
+ [QUEUE_FLAG_NOMERGES] = "NOMERGES",
+ [QUEUE_FLAG_SAME_COMP] = "SAME_COMP",
+ [QUEUE_FLAG_FAIL_IO] = "FAIL_IO",
+ [QUEUE_FLAG_STACKABLE] = "STACKABLE",
+ [QUEUE_FLAG_NONROT] = "NONROT",
+ [QUEUE_FLAG_IO_STAT] = "IO_STAT",
+ [QUEUE_FLAG_DISCARD] = "DISCARD",
+ [QUEUE_FLAG_NOXMERGES] = "NOXMERGES",
+ [QUEUE_FLAG_ADD_RANDOM] = "ADD_RANDOM",
+ [QUEUE_FLAG_SECERASE] = "SECERASE",
+ [QUEUE_FLAG_SAME_FORCE] = "SAME_FORCE",
+ [QUEUE_FLAG_DEAD] = "DEAD",
+ [QUEUE_FLAG_INIT_DONE] = "INIT_DONE",
+ [QUEUE_FLAG_NO_SG_MERGE] = "NO_SG_MERGE",
+ [QUEUE_FLAG_POLL] = "POLL",
+ [QUEUE_FLAG_WC] = "WC",
+ [QUEUE_FLAG_FUA] = "FUA",
+ [QUEUE_FLAG_FLUSH_NQ] = "FLUSH_NQ",
+ [QUEUE_FLAG_DAX] = "DAX",
+ [QUEUE_FLAG_STATS] = "STATS",
+ [QUEUE_FLAG_POLL_STATS] = "POLL_STATS",
+ [QUEUE_FLAG_REGISTERED] = "REGISTERED",
+};
+
+static int blk_queue_flags_show(struct seq_file *m, void *v)
+{
+ struct request_queue *q = m->private;
+
+ blk_flags_show(m, q->queue_flags, blk_queue_flag_name,
+ ARRAY_SIZE(blk_queue_flag_name));
+ seq_puts(m, "\n");
+ return 0;
+}
+
+static ssize_t blk_queue_flags_store(struct file *file, const char __user *ubuf,
+ size_t len, loff_t *offp)
+{
+ struct request_queue *q = file_inode(file)->i_private;
+ char op[16] = { }, *s;
+
+ len = min(len, sizeof(op) - 1);
+ if (copy_from_user(op, ubuf, len))
+ return -EFAULT;
+ s = op;
+ strsep(&s, " \t\n"); /* strip trailing whitespace */
+ if (strcmp(op, "run") == 0) {
+ blk_mq_run_hw_queues(q, true);
+ } else if (strcmp(op, "start") == 0) {
+ blk_mq_start_stopped_hw_queues(q, true);
+ } else {
+ pr_err("%s: unsupported operation %s. Use either 'run' or 'start'\n",
+ __func__, op);
+ return -EINVAL;
+ }
+ return len;
+}
+
+static int blk_queue_flags_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, blk_queue_flags_show, inode->i_private);
+}
+
+static const struct file_operations blk_queue_flags_fops = {
+ .open = blk_queue_flags_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+ .write = blk_queue_flags_store,
+};
+
+static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
+{
+ if (stat->nr_samples) {
+ seq_printf(m, "samples=%d, mean=%lld, min=%llu, max=%llu",
+ stat->nr_samples, stat->mean, stat->min, stat->max);
+ } else {
+ seq_puts(m, "samples=0");
+ }
+}
+
+static int queue_poll_stat_show(struct seq_file *m, void *v)
+{
+ struct request_queue *q = m->private;
+ int bucket;
+
+ for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS/2; bucket++) {
+ seq_printf(m, "read (%d Bytes): ", 1 << (9+bucket));
+ print_stat(m, &q->poll_stat[2*bucket]);
+ seq_puts(m, "\n");
+
+ seq_printf(m, "write (%d Bytes): ", 1 << (9+bucket));
+ print_stat(m, &q->poll_stat[2*bucket+1]);
+ seq_puts(m, "\n");
+ }
+ return 0;
+}
+
+static int queue_poll_stat_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, queue_poll_stat_show, inode->i_private);
+}
+
+static const struct file_operations queue_poll_stat_fops = {
+ .open = queue_poll_stat_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static const char *const hctx_state_name[] = {
+ [BLK_MQ_S_STOPPED] = "STOPPED",
+ [BLK_MQ_S_TAG_ACTIVE] = "TAG_ACTIVE",
+ [BLK_MQ_S_SCHED_RESTART] = "SCHED_RESTART",
+ [BLK_MQ_S_TAG_WAITING] = "TAG_WAITING",
+
+};
static int hctx_state_show(struct seq_file *m, void *v)
{
struct blk_mq_hw_ctx *hctx = m->private;
- seq_printf(m, "0x%lx\n", hctx->state);
+ blk_flags_show(m, hctx->state, hctx_state_name,
+ ARRAY_SIZE(hctx_state_name));
+ seq_puts(m, "\n");
return 0;
}
@@ -63,11 +209,35 @@ static const struct file_operations hctx_state_fops = {
.release = single_release,
};
+static const char *const alloc_policy_name[] = {
+ [BLK_TAG_ALLOC_FIFO] = "fifo",
+ [BLK_TAG_ALLOC_RR] = "rr",
+};
+
+static const char *const hctx_flag_name[] = {
+ [ilog2(BLK_MQ_F_SHOULD_MERGE)] = "SHOULD_MERGE",
+ [ilog2(BLK_MQ_F_TAG_SHARED)] = "TAG_SHARED",
+ [ilog2(BLK_MQ_F_SG_MERGE)] = "SG_MERGE",
+ [ilog2(BLK_MQ_F_BLOCKING)] = "BLOCKING",
+ [ilog2(BLK_MQ_F_NO_SCHED)] = "NO_SCHED",
+};
+
static int hctx_flags_show(struct seq_file *m, void *v)
{
struct blk_mq_hw_ctx *hctx = m->private;
-
- seq_printf(m, "0x%lx\n", hctx->flags);
+ const int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(hctx->flags);
+
+ seq_puts(m, "alloc_policy=");
+ if (alloc_policy < ARRAY_SIZE(alloc_policy_name) &&
+ alloc_policy_name[alloc_policy])
+ seq_puts(m, alloc_policy_name[alloc_policy]);
+ else
+ seq_printf(m, "%d", alloc_policy);
+ seq_puts(m, " ");
+ blk_flags_show(m,
+ hctx->flags ^ BLK_ALLOC_POLICY_TO_MQ_FLAG(alloc_policy),
+ hctx_flag_name, ARRAY_SIZE(hctx_flag_name));
+ seq_puts(m, "\n");
return 0;
}
@@ -83,13 +253,83 @@ static const struct file_operations hctx_flags_fops = {
.release = single_release,
};
+static const char *const op_name[] = {
+ [REQ_OP_READ] = "READ",
+ [REQ_OP_WRITE] = "WRITE",
+ [REQ_OP_FLUSH] = "FLUSH",
+ [REQ_OP_DISCARD] = "DISCARD",
+ [REQ_OP_ZONE_REPORT] = "ZONE_REPORT",
+ [REQ_OP_SECURE_ERASE] = "SECURE_ERASE",
+ [REQ_OP_ZONE_RESET] = "ZONE_RESET",
+ [REQ_OP_WRITE_SAME] = "WRITE_SAME",
+ [REQ_OP_WRITE_ZEROES] = "WRITE_ZEROES",
+ [REQ_OP_SCSI_IN] = "SCSI_IN",
+ [REQ_OP_SCSI_OUT] = "SCSI_OUT",
+ [REQ_OP_DRV_IN] = "DRV_IN",
+ [REQ_OP_DRV_OUT] = "DRV_OUT",
+};
+
+static const char *const cmd_flag_name[] = {
+ [__REQ_FAILFAST_DEV] = "FAILFAST_DEV",
+ [__REQ_FAILFAST_TRANSPORT] = "FAILFAST_TRANSPORT",
+ [__REQ_FAILFAST_DRIVER] = "FAILFAST_DRIVER",
+ [__REQ_SYNC] = "SYNC",
+ [__REQ_META] = "META",
+ [__REQ_PRIO] = "PRIO",
+ [__REQ_NOMERGE] = "NOMERGE",
+ [__REQ_IDLE] = "IDLE",
+ [__REQ_INTEGRITY] = "INTEGRITY",
+ [__REQ_FUA] = "FUA",
+ [__REQ_PREFLUSH] = "PREFLUSH",
+ [__REQ_RAHEAD] = "RAHEAD",
+ [__REQ_BACKGROUND] = "BACKGROUND",
+ [__REQ_NR_BITS] = "NR_BITS",
+};
+
+static const char *const rqf_name[] = {
+ [ilog2((__force u32)RQF_SORTED)] = "SORTED",
+ [ilog2((__force u32)RQF_STARTED)] = "STARTED",
+ [ilog2((__force u32)RQF_QUEUED)] = "QUEUED",
+ [ilog2((__force u32)RQF_SOFTBARRIER)] = "SOFTBARRIER",
+ [ilog2((__force u32)RQF_FLUSH_SEQ)] = "FLUSH_SEQ",
+ [ilog2((__force u32)RQF_MIXED_MERGE)] = "MIXED_MERGE",
+ [ilog2((__force u32)RQF_MQ_INFLIGHT)] = "MQ_INFLIGHT",
+ [ilog2((__force u32)RQF_DONTPREP)] = "DONTPREP",
+ [ilog2((__force u32)RQF_PREEMPT)] = "PREEMPT",
+ [ilog2((__force u32)RQF_COPY_USER)] = "COPY_USER",
+ [ilog2((__force u32)RQF_FAILED)] = "FAILED",
+ [ilog2((__force u32)RQF_QUIET)] = "QUIET",
+ [ilog2((__force u32)RQF_ELVPRIV)] = "ELVPRIV",
+ [ilog2((__force u32)RQF_IO_STAT)] = "IO_STAT",
+ [ilog2((__force u32)RQF_ALLOCED)] = "ALLOCED",
+ [ilog2((__force u32)RQF_PM)] = "PM",
+ [ilog2((__force u32)RQF_HASHED)] = "HASHED",
+ [ilog2((__force u32)RQF_STATS)] = "STATS",
+ [ilog2((__force u32)RQF_SPECIAL_PAYLOAD)] = "SPECIAL_PAYLOAD",
+};
+
static int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
{
struct request *rq = list_entry_rq(v);
-
- seq_printf(m, "%p {.cmd_flags=0x%x, .rq_flags=0x%x, .tag=%d, .internal_tag=%d}\n",
- rq, rq->cmd_flags, (__force unsigned int)rq->rq_flags,
- rq->tag, rq->internal_tag);
+ const struct blk_mq_ops *const mq_ops = rq->q->mq_ops;
+ const unsigned int op = rq->cmd_flags & REQ_OP_MASK;
+
+ seq_printf(m, "%p {.op=", rq);
+ if (op < ARRAY_SIZE(op_name) && op_name[op])
+ seq_printf(m, "%s", op_name[op]);
+ else
+ seq_printf(m, "%d", op);
+ seq_puts(m, ", .cmd_flags=");
+ blk_flags_show(m, rq->cmd_flags & ~REQ_OP_MASK, cmd_flag_name,
+ ARRAY_SIZE(cmd_flag_name));
+ seq_puts(m, ", .rq_flags=");
+ blk_flags_show(m, (__force unsigned int)rq->rq_flags, rqf_name,
+ ARRAY_SIZE(rqf_name));
+ seq_printf(m, ", .tag=%d, .internal_tag=%d", rq->tag,
+ rq->internal_tag);
+ if (mq_ops->show_rq)
+ mq_ops->show_rq(m, rq);
+ seq_puts(m, "}\n");
return 0;
}
@@ -322,60 +562,6 @@ static const struct file_operations hctx_io_poll_fops = {
.release = single_release,
};
-static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
-{
- seq_printf(m, "samples=%d, mean=%lld, min=%llu, max=%llu",
- stat->nr_samples, stat->mean, stat->min, stat->max);
-}
-
-static int hctx_stats_show(struct seq_file *m, void *v)
-{
- struct blk_mq_hw_ctx *hctx = m->private;
- struct blk_rq_stat stat[2];
-
- blk_stat_init(&stat[BLK_STAT_READ]);
- blk_stat_init(&stat[BLK_STAT_WRITE]);
-
- blk_hctx_stat_get(hctx, stat);
-
- seq_puts(m, "read: ");
- print_stat(m, &stat[BLK_STAT_READ]);
- seq_puts(m, "\n");
-
- seq_puts(m, "write: ");
- print_stat(m, &stat[BLK_STAT_WRITE]);
- seq_puts(m, "\n");
- return 0;
-}
-
-static int hctx_stats_open(struct inode *inode, struct file *file)
-{
- return single_open(file, hctx_stats_show, inode->i_private);
-}
-
-static ssize_t hctx_stats_write(struct file *file, const char __user *buf,
- size_t count, loff_t *ppos)
-{
- struct seq_file *m = file->private_data;
- struct blk_mq_hw_ctx *hctx = m->private;
- struct blk_mq_ctx *ctx;
- int i;
-
- hctx_for_each_ctx(hctx, ctx, i) {
- blk_stat_init(&ctx->stat[BLK_STAT_READ]);
- blk_stat_init(&ctx->stat[BLK_STAT_WRITE]);
- }
- return count;
-}
-
-static const struct file_operations hctx_stats_fops = {
- .open = hctx_stats_open,
- .read = seq_read,
- .write = hctx_stats_write,
- .llseek = seq_lseek,
- .release = single_release,
-};
-
static int hctx_dispatched_show(struct seq_file *m, void *v)
{
struct blk_mq_hw_ctx *hctx = m->private;
@@ -636,6 +822,12 @@ static const struct file_operations ctx_completed_fops = {
.release = single_release,
};
+static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
+ {"poll_stat", 0400, &queue_poll_stat_fops},
+ {"state", 0600, &blk_queue_flags_fops},
+ {},
+};
+
static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
{"state", 0400, &hctx_state_fops},
{"flags", 0400, &hctx_flags_fops},
@@ -646,7 +838,6 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_hctx_attrs[] = {
{"sched_tags", 0400, &hctx_sched_tags_fops},
{"sched_tags_bitmap", 0400, &hctx_sched_tags_bitmap_fops},
{"io_poll", 0600, &hctx_io_poll_fops},
- {"stats", 0600, &hctx_stats_fops},
{"dispatched", 0600, &hctx_dispatched_fops},
{"queued", 0600, &hctx_queued_fops},
{"run", 0600, &hctx_run_fops},
@@ -662,16 +853,17 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
{},
};
-int blk_mq_debugfs_register(struct request_queue *q, const char *name)
+int blk_mq_debugfs_register(struct request_queue *q)
{
if (!blk_debugfs_root)
return -ENOENT;
- q->debugfs_dir = debugfs_create_dir(name, blk_debugfs_root);
+ q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent),
+ blk_debugfs_root);
if (!q->debugfs_dir)
goto err;
- if (blk_mq_debugfs_register_hctxs(q))
+ if (blk_mq_debugfs_register_mq(q))
goto err;
return 0;
@@ -741,7 +933,7 @@ static int blk_mq_debugfs_register_hctx(struct request_queue *q,
return 0;
}
-int blk_mq_debugfs_register_hctxs(struct request_queue *q)
+int blk_mq_debugfs_register_mq(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int i;
@@ -753,6 +945,9 @@ int blk_mq_debugfs_register_hctxs(struct request_queue *q)
if (!q->mq_debugfs_dir)
goto err;
+ if (!debugfs_create_files(q->mq_debugfs_dir, q, blk_mq_debugfs_queue_attrs))
+ goto err;
+
queue_for_each_hw_ctx(q, hctx, i) {
if (blk_mq_debugfs_register_hctx(q, hctx))
goto err;
@@ -761,11 +956,11 @@ int blk_mq_debugfs_register_hctxs(struct request_queue *q)
return 0;
err:
- blk_mq_debugfs_unregister_hctxs(q);
+ blk_mq_debugfs_unregister_mq(q);
return -ENOMEM;
}
-void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
+void blk_mq_debugfs_unregister_mq(struct request_queue *q)
{
debugfs_remove_recursive(q->mq_debugfs_dir);
q->mq_debugfs_dir = NULL;
diff --git a/block/blk-mq-pci.c b/block/blk-mq-pci.c
index 966c2169762e..0c3354cf3552 100644
--- a/block/blk-mq-pci.c
+++ b/block/blk-mq-pci.c
@@ -23,7 +23,7 @@
* @pdev: PCI device associated with @set.
*
* This function assumes the PCI device @pdev has at least as many available
- * interrupt vetors as @set has queues. It will then queuery the vector
+ * interrupt vectors as @set has queues. It will then query the vector
* corresponding to each queue for it's affinity mask and built queue mapping
* that maps a queue to the CPUs that have irq affinity for the corresponding
* vector.
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 09af8ff18719..8b361e192e8a 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -30,43 +30,6 @@ void blk_mq_sched_free_hctx_data(struct request_queue *q,
}
EXPORT_SYMBOL_GPL(blk_mq_sched_free_hctx_data);
-int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
- int (*init)(struct blk_mq_hw_ctx *),
- void (*exit)(struct blk_mq_hw_ctx *))
-{
- struct blk_mq_hw_ctx *hctx;
- int ret;
- int i;
-
- queue_for_each_hw_ctx(q, hctx, i) {
- hctx->sched_data = kmalloc_node(size, GFP_KERNEL, hctx->numa_node);
- if (!hctx->sched_data) {
- ret = -ENOMEM;
- goto error;
- }
-
- if (init) {
- ret = init(hctx);
- if (ret) {
- /*
- * We don't want to give exit() a partially
- * initialized sched_data. init() must clean up
- * if it fails.
- */
- kfree(hctx->sched_data);
- hctx->sched_data = NULL;
- goto error;
- }
- }
- }
-
- return 0;
-error:
- blk_mq_sched_free_hctx_data(q, exit);
- return ret;
-}
-EXPORT_SYMBOL_GPL(blk_mq_sched_init_hctx_data);
-
static void __blk_mq_sched_assign_ioc(struct request_queue *q,
struct request *rq,
struct bio *bio,
@@ -119,7 +82,11 @@ struct request *blk_mq_sched_get_request(struct request_queue *q,
if (likely(!data->hctx))
data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
- if (e) {
+ /*
+ * For a reserved tag, allocate a normal request since we might
+ * have driver dependencies on the value of the internal tag.
+ */
+ if (e && !(data->flags & BLK_MQ_REQ_RESERVED)) {
data->flags |= BLK_MQ_REQ_INTERNAL;
/*
@@ -171,7 +138,8 @@ void blk_mq_sched_put_request(struct request *rq)
void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
{
- struct elevator_queue *e = hctx->queue->elevator;
+ struct request_queue *q = hctx->queue;
+ struct elevator_queue *e = q->elevator;
const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
bool did_work = false;
LIST_HEAD(rq_list);
@@ -203,10 +171,10 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
*/
if (!list_empty(&rq_list)) {
blk_mq_sched_mark_restart_hctx(hctx);
- did_work = blk_mq_dispatch_rq_list(hctx, &rq_list);
+ did_work = blk_mq_dispatch_rq_list(q, &rq_list);
} else if (!has_sched_dispatch) {
blk_mq_flush_busy_ctxs(hctx, &rq_list);
- blk_mq_dispatch_rq_list(hctx, &rq_list);
+ blk_mq_dispatch_rq_list(q, &rq_list);
}
/*
@@ -222,26 +190,10 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
if (!rq)
break;
list_add(&rq->queuelist, &rq_list);
- } while (blk_mq_dispatch_rq_list(hctx, &rq_list));
+ } while (blk_mq_dispatch_rq_list(q, &rq_list));
}
}
-void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
- struct list_head *rq_list,
- struct request *(*get_rq)(struct blk_mq_hw_ctx *))
-{
- do {
- struct request *rq;
-
- rq = get_rq(hctx);
- if (!rq)
- break;
-
- list_add_tail(&rq->queuelist, rq_list);
- } while (1);
-}
-EXPORT_SYMBOL_GPL(blk_mq_sched_move_to_dispatch);
-
bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
struct request **merged_request)
{
@@ -317,25 +269,68 @@ static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
return true;
}
-static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
+static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
{
if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
- if (blk_mq_hctx_has_pending(hctx))
+ if (blk_mq_hctx_has_pending(hctx)) {
blk_mq_run_hw_queue(hctx, true);
+ return true;
+ }
}
+ return false;
}
-void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
-{
- struct request_queue *q = hctx->queue;
- unsigned int i;
+/**
+ * list_for_each_entry_rcu_rr - iterate in a round-robin fashion over rcu list
+ * @pos: loop cursor.
+ * @skip: the list element that will not be examined. Iteration starts at
+ * @skip->next.
+ * @head: head of the list to examine. This list must have at least one
+ * element, namely @skip.
+ * @member: name of the list_head structure within typeof(*pos).
+ */
+#define list_for_each_entry_rcu_rr(pos, skip, head, member) \
+ for ((pos) = (skip); \
+ (pos = (pos)->member.next != (head) ? list_entry_rcu( \
+ (pos)->member.next, typeof(*pos), member) : \
+ list_entry_rcu((pos)->member.next->next, typeof(*pos), member)), \
+ (pos) != (skip); )
- if (test_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
- if (test_and_clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
- queue_for_each_hw_ctx(q, hctx, i)
- blk_mq_sched_restart_hctx(hctx);
+/*
+ * Called after a driver tag has been freed to check whether a hctx needs to
+ * be restarted. Restarts @hctx if its tag set is not shared. Restarts hardware
+ * queues in a round-robin fashion if the tag set of @hctx is shared with other
+ * hardware queues.
+ */
+void blk_mq_sched_restart(struct blk_mq_hw_ctx *const hctx)
+{
+ struct blk_mq_tags *const tags = hctx->tags;
+ struct blk_mq_tag_set *const set = hctx->queue->tag_set;
+ struct request_queue *const queue = hctx->queue, *q;
+ struct blk_mq_hw_ctx *hctx2;
+ unsigned int i, j;
+
+ if (set->flags & BLK_MQ_F_TAG_SHARED) {
+ rcu_read_lock();
+ list_for_each_entry_rcu_rr(q, queue, &set->tag_list,
+ tag_set_list) {
+ queue_for_each_hw_ctx(q, hctx2, i)
+ if (hctx2->tags == tags &&
+ blk_mq_sched_restart_hctx(hctx2))
+ goto done;
}
+ j = hctx->queue_num + 1;
+ for (i = 0; i < queue->nr_hw_queues; i++, j++) {
+ if (j == queue->nr_hw_queues)
+ j = 0;
+ hctx2 = queue->queue_hw_ctx[j];
+ if (hctx2->tags == tags &&
+ blk_mq_sched_restart_hctx(hctx2))
+ break;
+ }
+done:
+ rcu_read_unlock();
} else {
blk_mq_sched_restart_hctx(hctx);
}
@@ -431,11 +426,86 @@ static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
}
}
-int blk_mq_sched_setup(struct request_queue *q)
+static int blk_mq_sched_alloc_tags(struct request_queue *q,
+ struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx)
{
struct blk_mq_tag_set *set = q->tag_set;
+ int ret;
+
+ hctx->sched_tags = blk_mq_alloc_rq_map(set, hctx_idx, q->nr_requests,
+ set->reserved_tags);
+ if (!hctx->sched_tags)
+ return -ENOMEM;
+
+ ret = blk_mq_alloc_rqs(set, hctx->sched_tags, hctx_idx, q->nr_requests);
+ if (ret)
+ blk_mq_sched_free_tags(set, hctx, hctx_idx);
+
+ return ret;
+}
+
+static void blk_mq_sched_tags_teardown(struct request_queue *q)
+{
+ struct blk_mq_tag_set *set = q->tag_set;
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_sched_free_tags(set, hctx, i);
+}
+
+int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx)
+{
+ struct elevator_queue *e = q->elevator;
+ int ret;
+
+ if (!e)
+ return 0;
+
+ ret = blk_mq_sched_alloc_tags(q, hctx, hctx_idx);
+ if (ret)
+ return ret;
+
+ if (e->type->ops.mq.init_hctx) {
+ ret = e->type->ops.mq.init_hctx(hctx, hctx_idx);
+ if (ret) {
+ blk_mq_sched_free_tags(q->tag_set, hctx, hctx_idx);
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx)
+{
+ struct elevator_queue *e = q->elevator;
+
+ if (!e)
+ return;
+
+ if (e->type->ops.mq.exit_hctx && hctx->sched_data) {
+ e->type->ops.mq.exit_hctx(hctx, hctx_idx);
+ hctx->sched_data = NULL;
+ }
+
+ blk_mq_sched_free_tags(q->tag_set, hctx, hctx_idx);
+}
+
+int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
+{
struct blk_mq_hw_ctx *hctx;
- int ret, i;
+ struct elevator_queue *eq;
+ unsigned int i;
+ int ret;
+
+ if (!e) {
+ q->elevator = NULL;
+ return 0;
+ }
/*
* Default to 256, since we don't split into sync/async like the
@@ -443,49 +513,53 @@ int blk_mq_sched_setup(struct request_queue *q)
*/
q->nr_requests = 2 * BLKDEV_MAX_RQ;
- /*
- * We're switching to using an IO scheduler, so setup the hctx
- * scheduler tags and switch the request map from the regular
- * tags to scheduler tags. First allocate what we need, so we
- * can safely fail and fallback, if needed.
- */
- ret = 0;
queue_for_each_hw_ctx(q, hctx, i) {
- hctx->sched_tags = blk_mq_alloc_rq_map(set, i,
- q->nr_requests, set->reserved_tags);
- if (!hctx->sched_tags) {
- ret = -ENOMEM;
- break;
- }
- ret = blk_mq_alloc_rqs(set, hctx->sched_tags, i, q->nr_requests);
+ ret = blk_mq_sched_alloc_tags(q, hctx, i);
if (ret)
- break;
+ goto err;
}
- /*
- * If we failed, free what we did allocate
- */
- if (ret) {
+ ret = e->ops.mq.init_sched(q, e);
+ if (ret)
+ goto err;
+
+ if (e->ops.mq.init_hctx) {
queue_for_each_hw_ctx(q, hctx, i) {
- if (!hctx->sched_tags)
- continue;
- blk_mq_sched_free_tags(set, hctx, i);
+ ret = e->ops.mq.init_hctx(hctx, i);
+ if (ret) {
+ eq = q->elevator;
+ blk_mq_exit_sched(q, eq);
+ kobject_put(&eq->kobj);
+ return ret;
+ }
}
-
- return ret;
}
return 0;
+
+err:
+ blk_mq_sched_tags_teardown(q);
+ q->elevator = NULL;
+ return ret;
}
-void blk_mq_sched_teardown(struct request_queue *q)
+void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
{
- struct blk_mq_tag_set *set = q->tag_set;
struct blk_mq_hw_ctx *hctx;
- int i;
+ unsigned int i;
- queue_for_each_hw_ctx(q, hctx, i)
- blk_mq_sched_free_tags(set, hctx, i);
+ if (e->type->ops.mq.exit_hctx) {
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (hctx->sched_data) {
+ e->type->ops.mq.exit_hctx(hctx, i);
+ hctx->sched_data = NULL;
+ }
+ }
+ }
+ if (e->type->ops.mq.exit_sched)
+ e->type->ops.mq.exit_sched(e);
+ blk_mq_sched_tags_teardown(q);
+ q->elevator = NULL;
}
int blk_mq_sched_init(struct request_queue *q)
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index a75b16b123f7..edafb5383b7b 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -4,10 +4,6 @@
#include "blk-mq.h"
#include "blk-mq-tag.h"
-int blk_mq_sched_init_hctx_data(struct request_queue *q, size_t size,
- int (*init)(struct blk_mq_hw_ctx *),
- void (*exit)(struct blk_mq_hw_ctx *));
-
void blk_mq_sched_free_hctx_data(struct request_queue *q,
void (*exit)(struct blk_mq_hw_ctx *));
@@ -19,7 +15,7 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
struct request **merged_request);
bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio);
bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq);
-void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx);
+void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx);
void blk_mq_sched_insert_request(struct request *rq, bool at_head,
bool run_queue, bool async, bool can_block);
@@ -28,12 +24,14 @@ void blk_mq_sched_insert_requests(struct request_queue *q,
struct list_head *list, bool run_queue_async);
void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx);
-void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx,
- struct list_head *rq_list,
- struct request *(*get_rq)(struct blk_mq_hw_ctx *));
-int blk_mq_sched_setup(struct request_queue *q);
-void blk_mq_sched_teardown(struct request_queue *q);
+int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e);
+void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e);
+
+int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx);
+void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
+ unsigned int hctx_idx);
int blk_mq_sched_init(struct request_queue *q);
@@ -81,17 +79,12 @@ blk_mq_sched_allow_merge(struct request_queue *q, struct request *rq,
return true;
}
-static inline void
-blk_mq_sched_completed_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
+static inline void blk_mq_sched_completed_request(struct request *rq)
{
- struct elevator_queue *e = hctx->queue->elevator;
+ struct elevator_queue *e = rq->q->elevator;
if (e && e->type->ops.mq.completed_request)
- e->type->ops.mq.completed_request(hctx, rq);
-
- BUG_ON(rq->internal_tag == -1);
-
- blk_mq_put_tag(hctx, hctx->sched_tags, rq->mq_ctx, rq->internal_tag);
+ e->type->ops.mq.completed_request(rq);
}
static inline void blk_mq_sched_started_request(struct request *rq)
@@ -131,20 +124,6 @@ static inline void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx)
set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
}
-/*
- * Mark a hardware queue and the request queue it belongs to as needing a
- * restart.
- */
-static inline void blk_mq_sched_mark_restart_queue(struct blk_mq_hw_ctx *hctx)
-{
- struct request_queue *q = hctx->queue;
-
- if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
- set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
- if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
- set_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
-}
-
static inline bool blk_mq_sched_needs_restart(struct blk_mq_hw_ctx *hctx)
{
return test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index d745ab81033a..ec0afdf765e3 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -253,10 +253,12 @@ static void __blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
+ lockdep_assert_held(&q->sysfs_lock);
+
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_unregister_hctx(hctx);
- blk_mq_debugfs_unregister_hctxs(q);
+ blk_mq_debugfs_unregister_mq(q);
kobject_uevent(&q->mq_kobj, KOBJ_REMOVE);
kobject_del(&q->mq_kobj);
@@ -267,9 +269,9 @@ static void __blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
void blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
{
- blk_mq_disable_hotplug();
+ mutex_lock(&q->sysfs_lock);
__blk_mq_unregister_dev(dev, q);
- blk_mq_enable_hotplug();
+ mutex_unlock(&q->sysfs_lock);
}
void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx)
@@ -302,12 +304,13 @@ void blk_mq_sysfs_init(struct request_queue *q)
}
}
-int blk_mq_register_dev(struct device *dev, struct request_queue *q)
+int __blk_mq_register_dev(struct device *dev, struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int ret, i;
- blk_mq_disable_hotplug();
+ WARN_ON_ONCE(!q->kobj.parent);
+ lockdep_assert_held(&q->sysfs_lock);
ret = kobject_add(&q->mq_kobj, kobject_get(&dev->kobj), "%s", "mq");
if (ret < 0)
@@ -315,20 +318,38 @@ int blk_mq_register_dev(struct device *dev, struct request_queue *q)
kobject_uevent(&q->mq_kobj, KOBJ_ADD);
- blk_mq_debugfs_register(q, kobject_name(&dev->kobj));
+ blk_mq_debugfs_register(q);
queue_for_each_hw_ctx(q, hctx, i) {
ret = blk_mq_register_hctx(hctx);
if (ret)
- break;
+ goto unreg;
}
- if (ret)
- __blk_mq_unregister_dev(dev, q);
- else
- q->mq_sysfs_init_done = true;
+ q->mq_sysfs_init_done = true;
+
out:
- blk_mq_enable_hotplug();
+ return ret;
+
+unreg:
+ while (--i >= 0)
+ blk_mq_unregister_hctx(q->queue_hw_ctx[i]);
+
+ blk_mq_debugfs_unregister_mq(q);
+
+ kobject_uevent(&q->mq_kobj, KOBJ_REMOVE);
+ kobject_del(&q->mq_kobj);
+ kobject_put(&dev->kobj);
+ return ret;
+}
+
+int blk_mq_register_dev(struct device *dev, struct request_queue *q)
+{
+ int ret;
+
+ mutex_lock(&q->sysfs_lock);
+ ret = __blk_mq_register_dev(dev, q);
+ mutex_unlock(&q->sysfs_lock);
return ret;
}
@@ -339,13 +360,17 @@ void blk_mq_sysfs_unregister(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
+ mutex_lock(&q->sysfs_lock);
if (!q->mq_sysfs_init_done)
- return;
+ goto unlock;
- blk_mq_debugfs_unregister_hctxs(q);
+ blk_mq_debugfs_unregister_mq(q);
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_unregister_hctx(hctx);
+
+unlock:
+ mutex_unlock(&q->sysfs_lock);
}
int blk_mq_sysfs_register(struct request_queue *q)
@@ -353,10 +378,11 @@ int blk_mq_sysfs_register(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i, ret = 0;
+ mutex_lock(&q->sysfs_lock);
if (!q->mq_sysfs_init_done)
- return ret;
+ goto unlock;
- blk_mq_debugfs_register_hctxs(q);
+ blk_mq_debugfs_register_mq(q);
queue_for_each_hw_ctx(q, hctx, i) {
ret = blk_mq_register_hctx(hctx);
@@ -364,5 +390,8 @@ int blk_mq_sysfs_register(struct request_queue *q)
break;
}
+unlock:
+ mutex_unlock(&q->sysfs_lock);
+
return ret;
}
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 9d97bfc4d465..d0be72ccb091 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -96,7 +96,10 @@ static int __blk_mq_get_tag(struct blk_mq_alloc_data *data,
if (!(data->flags & BLK_MQ_REQ_INTERNAL) &&
!hctx_may_queue(data->hctx, bt))
return -1;
- return __sbitmap_queue_get(bt);
+ if (data->shallow_depth)
+ return __sbitmap_queue_get_shallow(bt, data->shallow_depth);
+ else
+ return __sbitmap_queue_get(bt);
}
unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 08a49c69738b..bf90684a007a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -39,6 +39,26 @@
static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
+static void blk_mq_poll_stats_start(struct request_queue *q);
+static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
+
+static int blk_mq_poll_stats_bkt(const struct request *rq)
+{
+ int ddir, bytes, bucket;
+
+ ddir = rq_data_dir(rq);
+ bytes = blk_rq_bytes(rq);
+
+ bucket = ddir + 2*(ilog2(bytes) - 9);
+
+ if (bucket < 0)
+ return -1;
+ else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
+ return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
+
+ return bucket;
+}
+
/*
* Check if any of the ctx's have pending work in this hardware queue
*/
@@ -65,7 +85,7 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
}
-void blk_mq_freeze_queue_start(struct request_queue *q)
+void blk_freeze_queue_start(struct request_queue *q)
{
int freeze_depth;
@@ -75,7 +95,7 @@ void blk_mq_freeze_queue_start(struct request_queue *q)
blk_mq_run_hw_queues(q, false);
}
}
-EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
+EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
void blk_mq_freeze_queue_wait(struct request_queue *q)
{
@@ -105,7 +125,7 @@ void blk_freeze_queue(struct request_queue *q)
* no blk_unfreeze_queue(), and blk_freeze_queue() is not
* exported to drivers as the only user for unfreeze is blk_mq.
*/
- blk_mq_freeze_queue_start(q);
+ blk_freeze_queue_start(q);
blk_mq_freeze_queue_wait(q);
}
@@ -210,7 +230,6 @@ void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
#endif
rq->special = NULL;
/* tag was already set */
- rq->errors = 0;
rq->extra_len = 0;
INIT_LIST_HEAD(&rq->timeout_list);
@@ -321,7 +340,6 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
- blk_mq_put_ctx(alloc_data.ctx);
blk_queue_exit(q);
if (!rq)
@@ -348,8 +366,8 @@ void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
if (rq->tag != -1)
blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
if (sched_tag != -1)
- blk_mq_sched_completed_request(hctx, rq);
- blk_mq_sched_restart_queues(hctx);
+ blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
+ blk_mq_sched_restart(hctx);
blk_queue_exit(q);
}
@@ -366,6 +384,7 @@ void blk_mq_finish_request(struct request *rq)
{
blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
}
+EXPORT_SYMBOL_GPL(blk_mq_finish_request);
void blk_mq_free_request(struct request *rq)
{
@@ -403,12 +422,19 @@ static void __blk_mq_complete_request_remote(void *data)
rq->q->softirq_done_fn(rq);
}
-static void blk_mq_ipi_complete_request(struct request *rq)
+static void __blk_mq_complete_request(struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
bool shared = false;
int cpu;
+ if (rq->internal_tag != -1)
+ blk_mq_sched_completed_request(rq);
+ if (rq->rq_flags & RQF_STATS) {
+ blk_mq_poll_stats_start(rq->q);
+ blk_stat_add(rq);
+ }
+
if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
rq->q->softirq_done_fn(rq);
return;
@@ -429,33 +455,6 @@ static void blk_mq_ipi_complete_request(struct request *rq)
put_cpu();
}
-static void blk_mq_stat_add(struct request *rq)
-{
- if (rq->rq_flags & RQF_STATS) {
- /*
- * We could rq->mq_ctx here, but there's less of a risk
- * of races if we have the completion event add the stats
- * to the local software queue.
- */
- struct blk_mq_ctx *ctx;
-
- ctx = __blk_mq_get_ctx(rq->q, raw_smp_processor_id());
- blk_stat_add(&ctx->stat[rq_data_dir(rq)], rq);
- }
-}
-
-static void __blk_mq_complete_request(struct request *rq)
-{
- struct request_queue *q = rq->q;
-
- blk_mq_stat_add(rq);
-
- if (!q->softirq_done_fn)
- blk_mq_end_request(rq, rq->errors);
- else
- blk_mq_ipi_complete_request(rq);
-}
-
/**
* blk_mq_complete_request - end I/O on a request
* @rq: the request being processed
@@ -464,16 +463,14 @@ static void __blk_mq_complete_request(struct request *rq)
* Ends all I/O on a request. It does not handle partial completions.
* The actual completion happens out-of-order, through a IPI handler.
**/
-void blk_mq_complete_request(struct request *rq, int error)
+void blk_mq_complete_request(struct request *rq)
{
struct request_queue *q = rq->q;
if (unlikely(blk_should_fake_timeout(q)))
return;
- if (!blk_mark_rq_complete(rq)) {
- rq->errors = error;
+ if (!blk_mark_rq_complete(rq))
__blk_mq_complete_request(rq);
- }
}
EXPORT_SYMBOL(blk_mq_complete_request);
@@ -492,7 +489,7 @@ void blk_mq_start_request(struct request *rq)
trace_block_rq_issue(q, rq);
if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
- blk_stat_set_issue_time(&rq->issue_stat);
+ blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
rq->rq_flags |= RQF_STATS;
wbt_issue(q->rq_wb, &rq->issue_stat);
}
@@ -527,6 +524,15 @@ void blk_mq_start_request(struct request *rq)
}
EXPORT_SYMBOL(blk_mq_start_request);
+/*
+ * When we reach here because queue is busy, REQ_ATOM_COMPLETE
+ * flag isn't set yet, so there may be race with timeout handler,
+ * but given rq->deadline is just set in .queue_rq() under
+ * this situation, the race won't be possible in reality because
+ * rq->timeout should be set as big enough to cover the window
+ * between blk_mq_start_request() called from .queue_rq() and
+ * clearing REQ_ATOM_STARTED here.
+ */
static void __blk_mq_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
@@ -634,8 +640,7 @@ void blk_mq_abort_requeue_list(struct request_queue *q)
rq = list_first_entry(&rq_list, struct request, queuelist);
list_del_init(&rq->queuelist);
- rq->errors = -EIO;
- blk_mq_end_request(rq, rq->errors);
+ blk_mq_end_request(rq, -EIO);
}
}
EXPORT_SYMBOL(blk_mq_abort_requeue_list);
@@ -667,7 +672,7 @@ void blk_mq_rq_timed_out(struct request *req, bool reserved)
* just be ignored. This can happen due to the bitflag ordering.
* Timeout first checks if STARTED is set, and if it is, assumes
* the request is active. But if we race with completion, then
- * we both flags will get cleared. So check here again, and ignore
+ * both flags will get cleared. So check here again, and ignore
* a timeout event with a request that isn't active.
*/
if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
@@ -700,6 +705,19 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
return;
+ /*
+ * The rq being checked may have been freed and reallocated
+ * out already here, we avoid this race by checking rq->deadline
+ * and REQ_ATOM_COMPLETE flag together:
+ *
+ * - if rq->deadline is observed as new value because of
+ * reusing, the rq won't be timed out because of timing.
+ * - if rq->deadline is observed as previous value,
+ * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
+ * because we put a barrier between setting rq->deadline
+ * and clearing the flag in blk_mq_start_request(), so
+ * this rq won't be timed out too.
+ */
if (time_after_eq(jiffies, rq->deadline)) {
if (!blk_mark_rq_complete(rq))
blk_mq_rq_timed_out(rq, reserved);
@@ -728,7 +746,7 @@ static void blk_mq_timeout_work(struct work_struct *work)
* percpu_ref_tryget directly, because we need to be able to
* obtain a reference even in the short window between the queue
* starting to freeze, by dropping the first reference in
- * blk_mq_freeze_queue_start, and the moment the last request is
+ * blk_freeze_queue_start, and the moment the last request is
* consumed, marked by the instant q_usage_counter reaches
* zero.
*/
@@ -846,12 +864,10 @@ bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
.flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
};
- if (rq->tag != -1) {
-done:
- if (hctx)
- *hctx = data.hctx;
- return true;
- }
+ might_sleep_if(wait);
+
+ if (rq->tag != -1)
+ goto done;
if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
data.flags |= BLK_MQ_REQ_RESERVED;
@@ -863,10 +879,12 @@ done:
atomic_inc(&data.hctx->nr_active);
}
data.hctx->tags->rqs[rq->tag] = rq;
- goto done;
}
- return false;
+done:
+ if (hctx)
+ *hctx = data.hctx;
+ return rq->tag != -1;
}
static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
@@ -963,25 +981,20 @@ static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
return true;
}
-bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
+bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
{
- struct request_queue *q = hctx->queue;
+ struct blk_mq_hw_ctx *hctx;
struct request *rq;
- LIST_HEAD(driver_list);
- struct list_head *dptr;
- int queued, ret = BLK_MQ_RQ_QUEUE_OK;
+ int errors, queued, ret = BLK_MQ_RQ_QUEUE_OK;
- /*
- * Start off with dptr being NULL, so we start the first request
- * immediately, even if we have more pending.
- */
- dptr = NULL;
+ if (list_empty(list))
+ return false;
/*
* Now process all the entries, sending them to the driver.
*/
- queued = 0;
- while (!list_empty(list)) {
+ errors = queued = 0;
+ do {
struct blk_mq_queue_data bd;
rq = list_first_entry(list, struct request, queuelist);
@@ -993,23 +1006,21 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
* The initial allocation attempt failed, so we need to
* rerun the hardware queue when a tag is freed.
*/
- if (blk_mq_dispatch_wait_add(hctx)) {
- /*
- * It's possible that a tag was freed in the
- * window between the allocation failure and
- * adding the hardware queue to the wait queue.
- */
- if (!blk_mq_get_driver_tag(rq, &hctx, false))
- break;
- } else {
+ if (!blk_mq_dispatch_wait_add(hctx))
+ break;
+
+ /*
+ * It's possible that a tag was freed in the window
+ * between the allocation failure and adding the
+ * hardware queue to the wait queue.
+ */
+ if (!blk_mq_get_driver_tag(rq, &hctx, false))
break;
- }
}
list_del_init(&rq->queuelist);
bd.rq = rq;
- bd.list = dptr;
/*
* Flag last if we have no more requests, or if we have more
@@ -1037,21 +1048,14 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
default:
pr_err("blk-mq: bad return on queue: %d\n", ret);
case BLK_MQ_RQ_QUEUE_ERROR:
- rq->errors = -EIO;
- blk_mq_end_request(rq, rq->errors);
+ errors++;
+ blk_mq_end_request(rq, -EIO);
break;
}
if (ret == BLK_MQ_RQ_QUEUE_BUSY)
break;
-
- /*
- * We've done the first request. If we have more than 1
- * left in the list, set dptr to defer issue.
- */
- if (!dptr && list->next != list->prev)
- dptr = &driver_list;
- }
+ } while (!list_empty(list));
hctx->dispatched[queued_to_index(queued)]++;
@@ -1061,8 +1065,8 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
*/
if (!list_empty(list)) {
/*
- * If we got a driver tag for the next request already,
- * free it again.
+ * If an I/O scheduler has been configured and we got a driver
+ * tag for the next request already, free it again.
*/
rq = list_first_entry(list, struct request, queuelist);
blk_mq_put_driver_tag(rq);
@@ -1072,23 +1076,31 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
spin_unlock(&hctx->lock);
/*
- * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
- * it's possible the queue is stopped and restarted again
- * before this. Queue restart will dispatch requests. And since
- * requests in rq_list aren't added into hctx->dispatch yet,
- * the requests in rq_list might get lost.
+ * If SCHED_RESTART was set by the caller of this function and
+ * it is no longer set that means that it was cleared by another
+ * thread and hence that a queue rerun is needed.
*
- * blk_mq_run_hw_queue() already checks the STOPPED bit
+ * If TAG_WAITING is set that means that an I/O scheduler has
+ * been configured and another thread is waiting for a driver
+ * tag. To guarantee fairness, do not rerun this hardware queue
+ * but let the other thread grab the driver tag.
*
- * If RESTART or TAG_WAITING is set, then let completion restart
- * the queue instead of potentially looping here.
+ * If no I/O scheduler has been configured it is possible that
+ * the hardware queue got stopped and restarted before requests
+ * were pushed back onto the dispatch list. Rerun the queue to
+ * avoid starvation. Notes:
+ * - blk_mq_run_hw_queue() checks whether or not a queue has
+ * been stopped before rerunning a queue.
+ * - Some but not all block drivers stop a queue before
+ * returning BLK_MQ_RQ_QUEUE_BUSY. Two exceptions are scsi-mq
+ * and dm-rq.
*/
if (!blk_mq_sched_needs_restart(hctx) &&
!test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
blk_mq_run_hw_queue(hctx, true);
}
- return queued != 0;
+ return (queued + errors) != 0;
}
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
@@ -1103,6 +1115,8 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
blk_mq_sched_dispatch_requests(hctx);
rcu_read_unlock();
} else {
+ might_sleep();
+
srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
blk_mq_sched_dispatch_requests(hctx);
srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
@@ -1134,7 +1148,8 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
return hctx->next_cpu;
}
-void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
+static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
+ unsigned long msecs)
{
if (unlikely(blk_mq_hctx_stopped(hctx) ||
!blk_mq_hw_queue_mapped(hctx)))
@@ -1151,8 +1166,22 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
put_cpu();
}
- kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
+ kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->run_work,
+ msecs_to_jiffies(msecs));
+}
+
+void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
+{
+ __blk_mq_delay_run_hw_queue(hctx, true, msecs);
+}
+EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
+
+void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
+{
+ __blk_mq_delay_run_hw_queue(hctx, async, 0);
}
+EXPORT_SYMBOL(blk_mq_run_hw_queue);
void blk_mq_run_hw_queues(struct request_queue *q, bool async)
{
@@ -1191,8 +1220,7 @@ EXPORT_SYMBOL(blk_mq_queue_stopped);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
- cancel_work(&hctx->run_work);
- cancel_delayed_work(&hctx->delay_work);
+ cancel_delayed_work_sync(&hctx->run_work);
set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);
@@ -1249,29 +1277,40 @@ static void blk_mq_run_work_fn(struct work_struct *work)
{
struct blk_mq_hw_ctx *hctx;
- hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
+ hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
- __blk_mq_run_hw_queue(hctx);
-}
-
-static void blk_mq_delay_work_fn(struct work_struct *work)
-{
- struct blk_mq_hw_ctx *hctx;
+ /*
+ * If we are stopped, don't run the queue. The exception is if
+ * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
+ * the STOPPED bit and run it.
+ */
+ if (test_bit(BLK_MQ_S_STOPPED, &hctx->state)) {
+ if (!test_bit(BLK_MQ_S_START_ON_RUN, &hctx->state))
+ return;
- hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
+ clear_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
+ clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
+ }
- if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
- __blk_mq_run_hw_queue(hctx);
+ __blk_mq_run_hw_queue(hctx);
}
+
void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
return;
+ /*
+ * Stop the hw queue, then modify currently delayed work.
+ * This should prevent us from running the queue prematurely.
+ * Mark the queue as auto-clearing STOPPED when it runs.
+ */
blk_mq_stop_hw_queue(hctx);
- kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
- &hctx->delay_work, msecs_to_jiffies(msecs));
+ set_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
+ kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->run_work,
+ msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_queue);
@@ -1380,7 +1419,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
{
- init_request_from_bio(rq, bio);
+ blk_init_request_from_bio(rq, bio);
blk_account_io_start(rq, true);
}
@@ -1425,14 +1464,13 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
}
-static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
+static void __blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
bool may_sleep)
{
struct request_queue *q = rq->q;
struct blk_mq_queue_data bd = {
.rq = rq,
- .list = NULL,
- .last = 1
+ .last = true,
};
struct blk_mq_hw_ctx *hctx;
blk_qc_t new_cookie;
@@ -1457,31 +1495,42 @@ static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
return;
}
- __blk_mq_requeue_request(rq);
-
if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
*cookie = BLK_QC_T_NONE;
- rq->errors = -EIO;
- blk_mq_end_request(rq, rq->errors);
+ blk_mq_end_request(rq, -EIO);
return;
}
+ __blk_mq_requeue_request(rq);
insert:
blk_mq_sched_insert_request(rq, false, true, false, may_sleep);
}
-/*
- * Multiple hardware queue variant. This will not use per-process plugs,
- * but will attempt to bypass the hctx queueing if we can go straight to
- * hardware for SYNC IO.
- */
+static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
+ struct request *rq, blk_qc_t *cookie)
+{
+ if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
+ rcu_read_lock();
+ __blk_mq_try_issue_directly(rq, cookie, false);
+ rcu_read_unlock();
+ } else {
+ unsigned int srcu_idx;
+
+ might_sleep();
+
+ srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
+ __blk_mq_try_issue_directly(rq, cookie, true);
+ srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
+ }
+}
+
static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
const int is_sync = op_is_sync(bio->bi_opf);
const int is_flush_fua = op_is_flush(bio->bi_opf);
struct blk_mq_alloc_data data = { .flags = 0 };
struct request *rq;
- unsigned int request_count = 0, srcu_idx;
+ unsigned int request_count = 0;
struct blk_plug *plug;
struct request *same_queue_rq = NULL;
blk_qc_t cookie;
@@ -1517,147 +1566,21 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
cookie = request_to_qc_t(data.hctx, rq);
- if (unlikely(is_flush_fua)) {
- if (q->elevator)
- goto elv_insert;
- blk_mq_bio_to_request(rq, bio);
- blk_insert_flush(rq);
- goto run_queue;
- }
-
plug = current->plug;
- /*
- * If the driver supports defer issued based on 'last', then
- * queue it up like normal since we can potentially save some
- * CPU this way.
- */
- if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
- !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
- struct request *old_rq = NULL;
-
- blk_mq_bio_to_request(rq, bio);
-
- /*
- * We do limited plugging. If the bio can be merged, do that.
- * Otherwise the existing request in the plug list will be
- * issued. So the plug list will have one request at most
- */
- if (plug) {
- /*
- * The plug list might get flushed before this. If that
- * happens, same_queue_rq is invalid and plug list is
- * empty
- */
- if (same_queue_rq && !list_empty(&plug->mq_list)) {
- old_rq = same_queue_rq;
- list_del_init(&old_rq->queuelist);
- }
- list_add_tail(&rq->queuelist, &plug->mq_list);
- } else /* is_sync */
- old_rq = rq;
+ if (unlikely(is_flush_fua)) {
blk_mq_put_ctx(data.ctx);
- if (!old_rq)
- goto done;
-
- if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
- rcu_read_lock();
- blk_mq_try_issue_directly(old_rq, &cookie, false);
- rcu_read_unlock();
+ blk_mq_bio_to_request(rq, bio);
+ if (q->elevator) {
+ blk_mq_sched_insert_request(rq, false, true, true,
+ true);
} else {
- srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
- blk_mq_try_issue_directly(old_rq, &cookie, true);
- srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
+ blk_insert_flush(rq);
+ blk_mq_run_hw_queue(data.hctx, true);
}
- goto done;
- }
-
- if (q->elevator) {
-elv_insert:
- blk_mq_put_ctx(data.ctx);
- blk_mq_bio_to_request(rq, bio);
- blk_mq_sched_insert_request(rq, false, true,
- !is_sync || is_flush_fua, true);
- goto done;
- }
- if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
- /*
- * For a SYNC request, send it to the hardware immediately. For
- * an ASYNC request, just ensure that we run it later on. The
- * latter allows for merging opportunities and more efficient
- * dispatching.
- */
-run_queue:
- blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
- }
- blk_mq_put_ctx(data.ctx);
-done:
- return cookie;
-}
-
-/*
- * Single hardware queue variant. This will attempt to use any per-process
- * plug for merging and IO deferral.
- */
-static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
-{
- const int is_sync = op_is_sync(bio->bi_opf);
- const int is_flush_fua = op_is_flush(bio->bi_opf);
- struct blk_plug *plug;
- unsigned int request_count = 0;
- struct blk_mq_alloc_data data = { .flags = 0 };
- struct request *rq;
- blk_qc_t cookie;
- unsigned int wb_acct;
-
- blk_queue_bounce(q, &bio);
-
- if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
- bio_io_error(bio);
- return BLK_QC_T_NONE;
- }
-
- blk_queue_split(q, &bio, q->bio_split);
-
- if (!is_flush_fua && !blk_queue_nomerges(q)) {
- if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
- return BLK_QC_T_NONE;
- } else
- request_count = blk_plug_queued_count(q);
-
- if (blk_mq_sched_bio_merge(q, bio))
- return BLK_QC_T_NONE;
-
- wb_acct = wbt_wait(q->rq_wb, bio, NULL);
-
- trace_block_getrq(q, bio, bio->bi_opf);
-
- rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
- if (unlikely(!rq)) {
- __wbt_done(q->rq_wb, wb_acct);
- return BLK_QC_T_NONE;
- }
-
- wbt_track(&rq->issue_stat, wb_acct);
-
- cookie = request_to_qc_t(data.hctx, rq);
-
- if (unlikely(is_flush_fua)) {
- if (q->elevator)
- goto elv_insert;
- blk_mq_bio_to_request(rq, bio);
- blk_insert_flush(rq);
- goto run_queue;
- }
-
- /*
- * A task plug currently exists. Since this is completely lockless,
- * utilize that to temporarily store requests until the task is
- * either done or scheduled away.
- */
- plug = current->plug;
- if (plug) {
+ } else if (plug && q->nr_hw_queues == 1) {
struct request *last = NULL;
+ blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
/*
@@ -1666,13 +1589,14 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
*/
if (list_empty(&plug->mq_list))
request_count = 0;
+ else if (blk_queue_nomerges(q))
+ request_count = blk_plug_queued_count(q);
+
if (!request_count)
trace_block_plug(q);
else
last = list_entry_rq(plug->mq_list.prev);
- blk_mq_put_ctx(data.ctx);
-
if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
blk_flush_plug_list(plug, false);
@@ -1680,30 +1604,41 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
}
list_add_tail(&rq->queuelist, &plug->mq_list);
- return cookie;
- }
-
- if (q->elevator) {
-elv_insert:
- blk_mq_put_ctx(data.ctx);
+ } else if (plug && !blk_queue_nomerges(q)) {
blk_mq_bio_to_request(rq, bio);
- blk_mq_sched_insert_request(rq, false, true,
- !is_sync || is_flush_fua, true);
- goto done;
- }
- if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
+
/*
- * For a SYNC request, send it to the hardware immediately. For
- * an ASYNC request, just ensure that we run it later on. The
- * latter allows for merging opportunities and more efficient
- * dispatching.
+ * We do limited plugging. If the bio can be merged, do that.
+ * Otherwise the existing request in the plug list will be
+ * issued. So the plug list will have one request at most
+ * The plug list might get flushed before this. If that happens,
+ * the plug list is empty, and same_queue_rq is invalid.
*/
-run_queue:
- blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
- }
+ if (list_empty(&plug->mq_list))
+ same_queue_rq = NULL;
+ if (same_queue_rq)
+ list_del_init(&same_queue_rq->queuelist);
+ list_add_tail(&rq->queuelist, &plug->mq_list);
+
+ blk_mq_put_ctx(data.ctx);
+
+ if (same_queue_rq)
+ blk_mq_try_issue_directly(data.hctx, same_queue_rq,
+ &cookie);
+ } else if (q->nr_hw_queues > 1 && is_sync) {
+ blk_mq_put_ctx(data.ctx);
+ blk_mq_bio_to_request(rq, bio);
+ blk_mq_try_issue_directly(data.hctx, rq, &cookie);
+ } else if (q->elevator) {
+ blk_mq_put_ctx(data.ctx);
+ blk_mq_bio_to_request(rq, bio);
+ blk_mq_sched_insert_request(rq, false, true, true, true);
+ } else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
+ blk_mq_put_ctx(data.ctx);
+ blk_mq_run_hw_queue(data.hctx, true);
+ } else
+ blk_mq_put_ctx(data.ctx);
- blk_mq_put_ctx(data.ctx);
-done:
return cookie;
}
@@ -1923,6 +1858,8 @@ static void blk_mq_exit_hctx(struct request_queue *q,
hctx->fq->flush_rq, hctx_idx,
flush_start_tag + hctx_idx);
+ blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
+
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
@@ -1958,8 +1895,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
if (node == NUMA_NO_NODE)
node = hctx->numa_node = set->numa_node;
- INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
- INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
+ INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
hctx->queue = q;
@@ -1989,9 +1925,12 @@ static int blk_mq_init_hctx(struct request_queue *q,
set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
goto free_bitmap;
+ if (blk_mq_sched_init_hctx(q, hctx, hctx_idx))
+ goto exit_hctx;
+
hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
if (!hctx->fq)
- goto exit_hctx;
+ goto sched_exit_hctx;
if (set->ops->init_request &&
set->ops->init_request(set->driver_data,
@@ -2006,6 +1945,8 @@ static int blk_mq_init_hctx(struct request_queue *q,
free_fq:
kfree(hctx->fq);
+ sched_exit_hctx:
+ blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
exit_hctx:
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
@@ -2031,8 +1972,6 @@ static void blk_mq_init_cpu_queues(struct request_queue *q,
spin_lock_init(&__ctx->lock);
INIT_LIST_HEAD(&__ctx->rq_list);
__ctx->queue = q;
- blk_stat_init(&__ctx->stat[BLK_STAT_READ]);
- blk_stat_init(&__ctx->stat[BLK_STAT_WRITE]);
/* If the cpu isn't online, the cpu is mapped to first hctx */
if (!cpu_online(i))
@@ -2179,6 +2118,8 @@ static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
{
struct request_queue *q;
+ lockdep_assert_held(&set->tag_list_lock);
+
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_freeze_queue(q);
queue_set_hctx_shared(q, shared);
@@ -2191,7 +2132,8 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
struct blk_mq_tag_set *set = q->tag_set;
mutex_lock(&set->tag_list_lock);
- list_del_init(&q->tag_set_list);
+ list_del_rcu(&q->tag_set_list);
+ INIT_LIST_HEAD(&q->tag_set_list);
if (list_is_singular(&set->tag_list)) {
/* just transitioned to unshared */
set->flags &= ~BLK_MQ_F_TAG_SHARED;
@@ -2199,6 +2141,8 @@ static void blk_mq_del_queue_tag_set(struct request_queue *q)
blk_mq_update_tag_set_depth(set, false);
}
mutex_unlock(&set->tag_list_lock);
+
+ synchronize_rcu();
}
static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
@@ -2216,7 +2160,7 @@ static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
}
if (set->flags & BLK_MQ_F_TAG_SHARED)
queue_set_hctx_shared(q, true);
- list_add_tail(&q->tag_set_list, &set->tag_list);
+ list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
mutex_unlock(&set->tag_list_lock);
}
@@ -2232,8 +2176,6 @@ void blk_mq_release(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
unsigned int i;
- blk_mq_sched_teardown(q);
-
/* hctx kobj stays in hctx */
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx)
@@ -2330,6 +2272,12 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
/* mark the queue as mq asap */
q->mq_ops = set->ops;
+ q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
+ blk_mq_poll_stats_bkt,
+ BLK_MQ_POLL_STATS_BKTS, q);
+ if (!q->poll_cb)
+ goto err_exit;
+
q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
if (!q->queue_ctx)
goto err_exit;
@@ -2364,10 +2312,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
INIT_LIST_HEAD(&q->requeue_list);
spin_lock_init(&q->requeue_lock);
- if (q->nr_hw_queues > 1)
- blk_queue_make_request(q, blk_mq_make_request);
- else
- blk_queue_make_request(q, blk_sq_make_request);
+ blk_queue_make_request(q, blk_mq_make_request);
/*
* Do this after blk_queue_make_request() overrides it...
@@ -2422,8 +2367,6 @@ void blk_mq_free_queue(struct request_queue *q)
list_del_init(&q->all_q_node);
mutex_unlock(&all_q_mutex);
- wbt_exit(q);
-
blk_mq_del_queue_tag_set(q);
blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
@@ -2468,7 +2411,7 @@ static void blk_mq_queue_reinit_work(void)
* take place in parallel.
*/
list_for_each_entry(q, &all_q_list, all_q_node)
- blk_mq_freeze_queue_start(q);
+ blk_freeze_queue_start(q);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_freeze_queue_wait(q);
@@ -2564,6 +2507,14 @@ static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
return 0;
}
+static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
+{
+ if (set->ops->map_queues)
+ return set->ops->map_queues(set);
+ else
+ return blk_mq_map_queues(set);
+}
+
/*
* Alloc a tag set to be associated with one or more request queues.
* May fail with EINVAL for various error conditions. May adjust the
@@ -2618,10 +2569,7 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
if (!set->mq_map)
goto out_free_tags;
- if (set->ops->map_queues)
- ret = set->ops->map_queues(set);
- else
- ret = blk_mq_map_queues(set);
+ ret = blk_mq_update_queue_map(set);
if (ret)
goto out_free_mq_map;
@@ -2704,6 +2652,8 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
{
struct request_queue *q;
+ lockdep_assert_held(&set->tag_list_lock);
+
if (nr_hw_queues > nr_cpu_ids)
nr_hw_queues = nr_cpu_ids;
if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
@@ -2713,18 +2663,9 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
blk_mq_freeze_queue(q);
set->nr_hw_queues = nr_hw_queues;
+ blk_mq_update_queue_map(set);
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_realloc_hw_ctxs(set, q);
-
- /*
- * Manually set the make_request_fn as blk_queue_make_request
- * resets a lot of the queue settings.
- */
- if (q->nr_hw_queues > 1)
- q->make_request_fn = blk_mq_make_request;
- else
- q->make_request_fn = blk_sq_make_request;
-
blk_mq_queue_reinit(q, cpu_online_mask);
}
@@ -2733,39 +2674,69 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
}
EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
+/* Enable polling stats and return whether they were already enabled. */
+static bool blk_poll_stats_enable(struct request_queue *q)
+{
+ if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
+ test_and_set_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
+ return true;
+ blk_stat_add_callback(q, q->poll_cb);
+ return false;
+}
+
+static void blk_mq_poll_stats_start(struct request_queue *q)
+{
+ /*
+ * We don't arm the callback if polling stats are not enabled or the
+ * callback is already active.
+ */
+ if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
+ blk_stat_is_active(q->poll_cb))
+ return;
+
+ blk_stat_activate_msecs(q->poll_cb, 100);
+}
+
+static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
+{
+ struct request_queue *q = cb->data;
+ int bucket;
+
+ for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
+ if (cb->stat[bucket].nr_samples)
+ q->poll_stat[bucket] = cb->stat[bucket];
+ }
+}
+
static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
- struct blk_rq_stat stat[2];
unsigned long ret = 0;
+ int bucket;
/*
* If stats collection isn't on, don't sleep but turn it on for
* future users
*/
- if (!blk_stat_enable(q))
+ if (!blk_poll_stats_enable(q))
return 0;
/*
- * We don't have to do this once per IO, should optimize this
- * to just use the current window of stats until it changes
- */
- memset(&stat, 0, sizeof(stat));
- blk_hctx_stat_get(hctx, stat);
-
- /*
* As an optimistic guess, use half of the mean service time
* for this type of request. We can (and should) make this smarter.
* For instance, if the completion latencies are tight, we can
* get closer than just half the mean. This is especially
* important on devices where the completion latencies are longer
- * than ~10 usec.
+ * than ~10 usec. We do use the stats for the relevant IO size
+ * if available which does lead to better estimates.
*/
- if (req_op(rq) == REQ_OP_READ && stat[BLK_STAT_READ].nr_samples)
- ret = (stat[BLK_STAT_READ].mean + 1) / 2;
- else if (req_op(rq) == REQ_OP_WRITE && stat[BLK_STAT_WRITE].nr_samples)
- ret = (stat[BLK_STAT_WRITE].mean + 1) / 2;
+ bucket = blk_mq_poll_stats_bkt(rq);
+ if (bucket < 0)
+ return ret;
+
+ if (q->poll_stat[bucket].nr_samples)
+ ret = (q->poll_stat[bucket].mean + 1) / 2;
return ret;
}
@@ -2888,8 +2859,17 @@ bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
if (!blk_qc_t_is_internal(cookie))
rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
- else
+ else {
rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
+ /*
+ * With scheduling, if the request has completed, we'll
+ * get a NULL return here, as we clear the sched tag when
+ * that happens. The request still remains valid, like always,
+ * so we should be safe with just the NULL check.
+ */
+ if (!rq)
+ return false;
+ }
return __blk_mq_poll(hctx, rq);
}
diff --git a/block/blk-mq.h b/block/blk-mq.h
index b79f9a7d8cf6..2814a14e529c 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -20,7 +20,6 @@ struct blk_mq_ctx {
/* incremented at completion time */
unsigned long ____cacheline_aligned_in_smp rq_completed[2];
- struct blk_rq_stat stat[2];
struct request_queue *queue;
struct kobject kobj;
@@ -31,7 +30,7 @@ void blk_mq_freeze_queue(struct request_queue *q);
void blk_mq_free_queue(struct request_queue *q);
int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr);
void blk_mq_wake_waiters(struct request_queue *q);
-bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *, struct list_head *);
+bool blk_mq_dispatch_rq_list(struct request_queue *, struct list_head *);
void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list);
bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx);
bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
@@ -79,6 +78,7 @@ static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
*/
extern void blk_mq_sysfs_init(struct request_queue *q);
extern void blk_mq_sysfs_deinit(struct request_queue *q);
+extern int __blk_mq_register_dev(struct device *dev, struct request_queue *q);
extern int blk_mq_sysfs_register(struct request_queue *q);
extern void blk_mq_sysfs_unregister(struct request_queue *q);
extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
@@ -87,13 +87,12 @@ extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
* debugfs helpers
*/
#ifdef CONFIG_BLK_DEBUG_FS
-int blk_mq_debugfs_register(struct request_queue *q, const char *name);
+int blk_mq_debugfs_register(struct request_queue *q);
void blk_mq_debugfs_unregister(struct request_queue *q);
-int blk_mq_debugfs_register_hctxs(struct request_queue *q);
-void blk_mq_debugfs_unregister_hctxs(struct request_queue *q);
+int blk_mq_debugfs_register_mq(struct request_queue *q);
+void blk_mq_debugfs_unregister_mq(struct request_queue *q);
#else
-static inline int blk_mq_debugfs_register(struct request_queue *q,
- const char *name)
+static inline int blk_mq_debugfs_register(struct request_queue *q)
{
return 0;
}
@@ -102,12 +101,12 @@ static inline void blk_mq_debugfs_unregister(struct request_queue *q)
{
}
-static inline int blk_mq_debugfs_register_hctxs(struct request_queue *q)
+static inline int blk_mq_debugfs_register_mq(struct request_queue *q)
{
return 0;
}
-static inline void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
+static inline void blk_mq_debugfs_unregister_mq(struct request_queue *q)
{
}
#endif
@@ -142,6 +141,7 @@ struct blk_mq_alloc_data {
/* input parameter */
struct request_queue *q;
unsigned int flags;
+ unsigned int shallow_depth;
/* input & output parameter */
struct blk_mq_ctx *ctx;
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 1e7174ffc9d4..4fa81ed383ca 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -103,7 +103,6 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->discard_granularity = 0;
lim->discard_alignment = 0;
lim->discard_misaligned = 0;
- lim->discard_zeroes_data = 0;
lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
lim->alignment_offset = 0;
@@ -127,7 +126,6 @@ void blk_set_stacking_limits(struct queue_limits *lim)
blk_set_default_limits(lim);
/* Inherit limits from component devices */
- lim->discard_zeroes_data = 1;
lim->max_segments = USHRT_MAX;
lim->max_discard_segments = 1;
lim->max_hw_sectors = UINT_MAX;
@@ -609,7 +607,6 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
t->cluster &= b->cluster;
- t->discard_zeroes_data &= b->discard_zeroes_data;
/* Physical block size a multiple of the logical block size? */
if (t->physical_block_size & (t->logical_block_size - 1)) {
diff --git a/block/blk-stat.c b/block/blk-stat.c
index 186fcb981e9b..6c2f40940439 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -4,10 +4,27 @@
* Copyright (C) 2016 Jens Axboe
*/
#include <linux/kernel.h>
+#include <linux/rculist.h>
#include <linux/blk-mq.h>
#include "blk-stat.h"
#include "blk-mq.h"
+#include "blk.h"
+
+#define BLK_RQ_STAT_BATCH 64
+
+struct blk_queue_stats {
+ struct list_head callbacks;
+ spinlock_t lock;
+ bool enable_accounting;
+};
+
+static void blk_stat_init(struct blk_rq_stat *stat)
+{
+ stat->min = -1ULL;
+ stat->max = stat->nr_samples = stat->mean = 0;
+ stat->batch = stat->nr_batch = 0;
+}
static void blk_stat_flush_batch(struct blk_rq_stat *stat)
{
@@ -48,209 +65,185 @@ static void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
dst->nr_samples += src->nr_samples;
}
-static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
+static void __blk_stat_add(struct blk_rq_stat *stat, u64 value)
{
- struct blk_mq_hw_ctx *hctx;
- struct blk_mq_ctx *ctx;
- uint64_t latest = 0;
- int i, j, nr;
-
- blk_stat_init(&dst[BLK_STAT_READ]);
- blk_stat_init(&dst[BLK_STAT_WRITE]);
-
- nr = 0;
- do {
- uint64_t newest = 0;
-
- queue_for_each_hw_ctx(q, hctx, i) {
- hctx_for_each_ctx(hctx, ctx, j) {
- blk_stat_flush_batch(&ctx->stat[BLK_STAT_READ]);
- blk_stat_flush_batch(&ctx->stat[BLK_STAT_WRITE]);
-
- if (!ctx->stat[BLK_STAT_READ].nr_samples &&
- !ctx->stat[BLK_STAT_WRITE].nr_samples)
- continue;
- if (ctx->stat[BLK_STAT_READ].time > newest)
- newest = ctx->stat[BLK_STAT_READ].time;
- if (ctx->stat[BLK_STAT_WRITE].time > newest)
- newest = ctx->stat[BLK_STAT_WRITE].time;
- }
- }
+ stat->min = min(stat->min, value);
+ stat->max = max(stat->max, value);
- /*
- * No samples
- */
- if (!newest)
- break;
-
- if (newest > latest)
- latest = newest;
-
- queue_for_each_hw_ctx(q, hctx, i) {
- hctx_for_each_ctx(hctx, ctx, j) {
- if (ctx->stat[BLK_STAT_READ].time == newest) {
- blk_stat_sum(&dst[BLK_STAT_READ],
- &ctx->stat[BLK_STAT_READ]);
- nr++;
- }
- if (ctx->stat[BLK_STAT_WRITE].time == newest) {
- blk_stat_sum(&dst[BLK_STAT_WRITE],
- &ctx->stat[BLK_STAT_WRITE]);
- nr++;
- }
- }
- }
- /*
- * If we race on finding an entry, just loop back again.
- * Should be very rare.
- */
- } while (!nr);
+ if (stat->batch + value < stat->batch ||
+ stat->nr_batch + 1 == BLK_RQ_STAT_BATCH)
+ blk_stat_flush_batch(stat);
- dst[BLK_STAT_READ].time = dst[BLK_STAT_WRITE].time = latest;
+ stat->batch += value;
+ stat->nr_batch++;
}
-void blk_queue_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
+void blk_stat_add(struct request *rq)
{
- if (q->mq_ops)
- blk_mq_stat_get(q, dst);
- else {
- blk_stat_flush_batch(&q->rq_stats[BLK_STAT_READ]);
- blk_stat_flush_batch(&q->rq_stats[BLK_STAT_WRITE]);
- memcpy(&dst[BLK_STAT_READ], &q->rq_stats[BLK_STAT_READ],
- sizeof(struct blk_rq_stat));
- memcpy(&dst[BLK_STAT_WRITE], &q->rq_stats[BLK_STAT_WRITE],
- sizeof(struct blk_rq_stat));
+ struct request_queue *q = rq->q;
+ struct blk_stat_callback *cb;
+ struct blk_rq_stat *stat;
+ int bucket;
+ s64 now, value;
+
+ now = __blk_stat_time(ktime_to_ns(ktime_get()));
+ if (now < blk_stat_time(&rq->issue_stat))
+ return;
+
+ value = now - blk_stat_time(&rq->issue_stat);
+
+ blk_throtl_stat_add(rq, value);
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(cb, &q->stats->callbacks, list) {
+ if (blk_stat_is_active(cb)) {
+ bucket = cb->bucket_fn(rq);
+ if (bucket < 0)
+ continue;
+ stat = &this_cpu_ptr(cb->cpu_stat)[bucket];
+ __blk_stat_add(stat, value);
+ }
}
+ rcu_read_unlock();
}
-void blk_hctx_stat_get(struct blk_mq_hw_ctx *hctx, struct blk_rq_stat *dst)
+static void blk_stat_timer_fn(unsigned long data)
{
- struct blk_mq_ctx *ctx;
- unsigned int i, nr;
+ struct blk_stat_callback *cb = (void *)data;
+ unsigned int bucket;
+ int cpu;
- nr = 0;
- do {
- uint64_t newest = 0;
+ for (bucket = 0; bucket < cb->buckets; bucket++)
+ blk_stat_init(&cb->stat[bucket]);
- hctx_for_each_ctx(hctx, ctx, i) {
- blk_stat_flush_batch(&ctx->stat[BLK_STAT_READ]);
- blk_stat_flush_batch(&ctx->stat[BLK_STAT_WRITE]);
+ for_each_online_cpu(cpu) {
+ struct blk_rq_stat *cpu_stat;
- if (!ctx->stat[BLK_STAT_READ].nr_samples &&
- !ctx->stat[BLK_STAT_WRITE].nr_samples)
- continue;
-
- if (ctx->stat[BLK_STAT_READ].time > newest)
- newest = ctx->stat[BLK_STAT_READ].time;
- if (ctx->stat[BLK_STAT_WRITE].time > newest)
- newest = ctx->stat[BLK_STAT_WRITE].time;
+ cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu);
+ for (bucket = 0; bucket < cb->buckets; bucket++) {
+ blk_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]);
+ blk_stat_init(&cpu_stat[bucket]);
}
+ }
- if (!newest)
- break;
-
- hctx_for_each_ctx(hctx, ctx, i) {
- if (ctx->stat[BLK_STAT_READ].time == newest) {
- blk_stat_sum(&dst[BLK_STAT_READ],
- &ctx->stat[BLK_STAT_READ]);
- nr++;
- }
- if (ctx->stat[BLK_STAT_WRITE].time == newest) {
- blk_stat_sum(&dst[BLK_STAT_WRITE],
- &ctx->stat[BLK_STAT_WRITE]);
- nr++;
- }
- }
- /*
- * If we race on finding an entry, just loop back again.
- * Should be very rare, as the window is only updated
- * occasionally
- */
- } while (!nr);
+ cb->timer_fn(cb);
}
-static void __blk_stat_init(struct blk_rq_stat *stat, s64 time_now)
+struct blk_stat_callback *
+blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),
+ int (*bucket_fn)(const struct request *),
+ unsigned int buckets, void *data)
{
- stat->min = -1ULL;
- stat->max = stat->nr_samples = stat->mean = 0;
- stat->batch = stat->nr_batch = 0;
- stat->time = time_now & BLK_STAT_NSEC_MASK;
-}
+ struct blk_stat_callback *cb;
-void blk_stat_init(struct blk_rq_stat *stat)
-{
- __blk_stat_init(stat, ktime_to_ns(ktime_get()));
-}
+ cb = kmalloc(sizeof(*cb), GFP_KERNEL);
+ if (!cb)
+ return NULL;
-static bool __blk_stat_is_current(struct blk_rq_stat *stat, s64 now)
-{
- return (now & BLK_STAT_NSEC_MASK) == (stat->time & BLK_STAT_NSEC_MASK);
+ cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat),
+ GFP_KERNEL);
+ if (!cb->stat) {
+ kfree(cb);
+ return NULL;
+ }
+ cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat),
+ __alignof__(struct blk_rq_stat));
+ if (!cb->cpu_stat) {
+ kfree(cb->stat);
+ kfree(cb);
+ return NULL;
+ }
+
+ cb->timer_fn = timer_fn;
+ cb->bucket_fn = bucket_fn;
+ cb->data = data;
+ cb->buckets = buckets;
+ setup_timer(&cb->timer, blk_stat_timer_fn, (unsigned long)cb);
+
+ return cb;
}
+EXPORT_SYMBOL_GPL(blk_stat_alloc_callback);
-bool blk_stat_is_current(struct blk_rq_stat *stat)
+void blk_stat_add_callback(struct request_queue *q,
+ struct blk_stat_callback *cb)
{
- return __blk_stat_is_current(stat, ktime_to_ns(ktime_get()));
+ unsigned int bucket;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct blk_rq_stat *cpu_stat;
+
+ cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu);
+ for (bucket = 0; bucket < cb->buckets; bucket++)
+ blk_stat_init(&cpu_stat[bucket]);
+ }
+
+ spin_lock(&q->stats->lock);
+ list_add_tail_rcu(&cb->list, &q->stats->callbacks);
+ set_bit(QUEUE_FLAG_STATS, &q->queue_flags);
+ spin_unlock(&q->stats->lock);
}
+EXPORT_SYMBOL_GPL(blk_stat_add_callback);
-void blk_stat_add(struct blk_rq_stat *stat, struct request *rq)
+void blk_stat_remove_callback(struct request_queue *q,
+ struct blk_stat_callback *cb)
{
- s64 now, value;
+ spin_lock(&q->stats->lock);
+ list_del_rcu(&cb->list);
+ if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting)
+ clear_bit(QUEUE_FLAG_STATS, &q->queue_flags);
+ spin_unlock(&q->stats->lock);
- now = __blk_stat_time(ktime_to_ns(ktime_get()));
- if (now < blk_stat_time(&rq->issue_stat))
- return;
-
- if (!__blk_stat_is_current(stat, now))
- __blk_stat_init(stat, now);
+ del_timer_sync(&cb->timer);
+}
+EXPORT_SYMBOL_GPL(blk_stat_remove_callback);
- value = now - blk_stat_time(&rq->issue_stat);
- if (value > stat->max)
- stat->max = value;
- if (value < stat->min)
- stat->min = value;
+static void blk_stat_free_callback_rcu(struct rcu_head *head)
+{
+ struct blk_stat_callback *cb;
- if (stat->batch + value < stat->batch ||
- stat->nr_batch + 1 == BLK_RQ_STAT_BATCH)
- blk_stat_flush_batch(stat);
+ cb = container_of(head, struct blk_stat_callback, rcu);
+ free_percpu(cb->cpu_stat);
+ kfree(cb->stat);
+ kfree(cb);
+}
- stat->batch += value;
- stat->nr_batch++;
+void blk_stat_free_callback(struct blk_stat_callback *cb)
+{
+ if (cb)
+ call_rcu(&cb->rcu, blk_stat_free_callback_rcu);
}
+EXPORT_SYMBOL_GPL(blk_stat_free_callback);
-void blk_stat_clear(struct request_queue *q)
+void blk_stat_enable_accounting(struct request_queue *q)
{
- if (q->mq_ops) {
- struct blk_mq_hw_ctx *hctx;
- struct blk_mq_ctx *ctx;
- int i, j;
-
- queue_for_each_hw_ctx(q, hctx, i) {
- hctx_for_each_ctx(hctx, ctx, j) {
- blk_stat_init(&ctx->stat[BLK_STAT_READ]);
- blk_stat_init(&ctx->stat[BLK_STAT_WRITE]);
- }
- }
- } else {
- blk_stat_init(&q->rq_stats[BLK_STAT_READ]);
- blk_stat_init(&q->rq_stats[BLK_STAT_WRITE]);
- }
+ spin_lock(&q->stats->lock);
+ q->stats->enable_accounting = true;
+ set_bit(QUEUE_FLAG_STATS, &q->queue_flags);
+ spin_unlock(&q->stats->lock);
}
-void blk_stat_set_issue_time(struct blk_issue_stat *stat)
+struct blk_queue_stats *blk_alloc_queue_stats(void)
{
- stat->time = (stat->time & BLK_STAT_MASK) |
- (ktime_to_ns(ktime_get()) & BLK_STAT_TIME_MASK);
+ struct blk_queue_stats *stats;
+
+ stats = kmalloc(sizeof(*stats), GFP_KERNEL);
+ if (!stats)
+ return NULL;
+
+ INIT_LIST_HEAD(&stats->callbacks);
+ spin_lock_init(&stats->lock);
+ stats->enable_accounting = false;
+
+ return stats;
}
-/*
- * Enable stat tracking, return whether it was enabled
- */
-bool blk_stat_enable(struct request_queue *q)
+void blk_free_queue_stats(struct blk_queue_stats *stats)
{
- if (!test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
- set_bit(QUEUE_FLAG_STATS, &q->queue_flags);
- return false;
- }
+ if (!stats)
+ return;
+
+ WARN_ON(!list_empty(&stats->callbacks));
- return true;
+ kfree(stats);
}
diff --git a/block/blk-stat.h b/block/blk-stat.h
index a2050a0a5314..2fb20d1a341a 100644
--- a/block/blk-stat.h
+++ b/block/blk-stat.h
@@ -1,33 +1,85 @@
#ifndef BLK_STAT_H
#define BLK_STAT_H
-/*
- * ~0.13s window as a power-of-2 (2^27 nsecs)
- */
-#define BLK_STAT_NSEC 134217728ULL
-#define BLK_STAT_NSEC_MASK ~(BLK_STAT_NSEC - 1)
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/ktime.h>
+#include <linux/rcupdate.h>
+#include <linux/timer.h>
/*
- * Upper 3 bits can be used elsewhere
+ * from upper:
+ * 3 bits: reserved for other usage
+ * 12 bits: size
+ * 49 bits: time
*/
#define BLK_STAT_RES_BITS 3
-#define BLK_STAT_SHIFT (64 - BLK_STAT_RES_BITS)
-#define BLK_STAT_TIME_MASK ((1ULL << BLK_STAT_SHIFT) - 1)
-#define BLK_STAT_MASK ~BLK_STAT_TIME_MASK
+#define BLK_STAT_SIZE_BITS 12
+#define BLK_STAT_RES_SHIFT (64 - BLK_STAT_RES_BITS)
+#define BLK_STAT_SIZE_SHIFT (BLK_STAT_RES_SHIFT - BLK_STAT_SIZE_BITS)
+#define BLK_STAT_TIME_MASK ((1ULL << BLK_STAT_SIZE_SHIFT) - 1)
+#define BLK_STAT_SIZE_MASK \
+ (((1ULL << BLK_STAT_SIZE_BITS) - 1) << BLK_STAT_SIZE_SHIFT)
+#define BLK_STAT_RES_MASK (~((1ULL << BLK_STAT_RES_SHIFT) - 1))
+
+/**
+ * struct blk_stat_callback - Block statistics callback.
+ *
+ * A &struct blk_stat_callback is associated with a &struct request_queue. While
+ * @timer is active, that queue's request completion latencies are sorted into
+ * buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the
+ * timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked.
+ */
+struct blk_stat_callback {
+ /*
+ * @list: RCU list of callbacks for a &struct request_queue.
+ */
+ struct list_head list;
+
+ /**
+ * @timer: Timer for the next callback invocation.
+ */
+ struct timer_list timer;
+
+ /**
+ * @cpu_stat: Per-cpu statistics buckets.
+ */
+ struct blk_rq_stat __percpu *cpu_stat;
+
+ /**
+ * @bucket_fn: Given a request, returns which statistics bucket it
+ * should be accounted under. Return -1 for no bucket for this
+ * request.
+ */
+ int (*bucket_fn)(const struct request *);
+
+ /**
+ * @buckets: Number of statistics buckets.
+ */
+ unsigned int buckets;
+
+ /**
+ * @stat: Array of statistics buckets.
+ */
+ struct blk_rq_stat *stat;
+
+ /**
+ * @fn: Callback function.
+ */
+ void (*timer_fn)(struct blk_stat_callback *);
+
+ /**
+ * @data: Private pointer for the user.
+ */
+ void *data;
-enum {
- BLK_STAT_READ = 0,
- BLK_STAT_WRITE,
+ struct rcu_head rcu;
};
-void blk_stat_add(struct blk_rq_stat *, struct request *);
-void blk_hctx_stat_get(struct blk_mq_hw_ctx *, struct blk_rq_stat *);
-void blk_queue_stat_get(struct request_queue *, struct blk_rq_stat *);
-void blk_stat_clear(struct request_queue *);
-void blk_stat_init(struct blk_rq_stat *);
-bool blk_stat_is_current(struct blk_rq_stat *);
-void blk_stat_set_issue_time(struct blk_issue_stat *);
-bool blk_stat_enable(struct request_queue *);
+struct blk_queue_stats *blk_alloc_queue_stats(void);
+void blk_free_queue_stats(struct blk_queue_stats *);
+
+void blk_stat_add(struct request *);
static inline u64 __blk_stat_time(u64 time)
{
@@ -36,7 +88,117 @@ static inline u64 __blk_stat_time(u64 time)
static inline u64 blk_stat_time(struct blk_issue_stat *stat)
{
- return __blk_stat_time(stat->time);
+ return __blk_stat_time(stat->stat);
+}
+
+static inline sector_t blk_capped_size(sector_t size)
+{
+ return size & ((1ULL << BLK_STAT_SIZE_BITS) - 1);
+}
+
+static inline sector_t blk_stat_size(struct blk_issue_stat *stat)
+{
+ return (stat->stat & BLK_STAT_SIZE_MASK) >> BLK_STAT_SIZE_SHIFT;
+}
+
+static inline void blk_stat_set_issue(struct blk_issue_stat *stat,
+ sector_t size)
+{
+ stat->stat = (stat->stat & BLK_STAT_RES_MASK) |
+ (ktime_to_ns(ktime_get()) & BLK_STAT_TIME_MASK) |
+ (((u64)blk_capped_size(size)) << BLK_STAT_SIZE_SHIFT);
+}
+
+/* record time/size info in request but not add a callback */
+void blk_stat_enable_accounting(struct request_queue *q);
+
+/**
+ * blk_stat_alloc_callback() - Allocate a block statistics callback.
+ * @timer_fn: Timer callback function.
+ * @bucket_fn: Bucket callback function.
+ * @buckets: Number of statistics buckets.
+ * @data: Value for the @data field of the &struct blk_stat_callback.
+ *
+ * See &struct blk_stat_callback for details on the callback functions.
+ *
+ * Return: &struct blk_stat_callback on success or NULL on ENOMEM.
+ */
+struct blk_stat_callback *
+blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),
+ int (*bucket_fn)(const struct request *),
+ unsigned int buckets, void *data);
+
+/**
+ * blk_stat_add_callback() - Add a block statistics callback to be run on a
+ * request queue.
+ * @q: The request queue.
+ * @cb: The callback.
+ *
+ * Note that a single &struct blk_stat_callback can only be added to a single
+ * &struct request_queue.
+ */
+void blk_stat_add_callback(struct request_queue *q,
+ struct blk_stat_callback *cb);
+
+/**
+ * blk_stat_remove_callback() - Remove a block statistics callback from a
+ * request queue.
+ * @q: The request queue.
+ * @cb: The callback.
+ *
+ * When this returns, the callback is not running on any CPUs and will not be
+ * called again unless readded.
+ */
+void blk_stat_remove_callback(struct request_queue *q,
+ struct blk_stat_callback *cb);
+
+/**
+ * blk_stat_free_callback() - Free a block statistics callback.
+ * @cb: The callback.
+ *
+ * @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must
+ * not be associated with a request queue. I.e., if it was previously added with
+ * blk_stat_add_callback(), it must also have been removed since then with
+ * blk_stat_remove_callback().
+ */
+void blk_stat_free_callback(struct blk_stat_callback *cb);
+
+/**
+ * blk_stat_is_active() - Check if a block statistics callback is currently
+ * gathering statistics.
+ * @cb: The callback.
+ */
+static inline bool blk_stat_is_active(struct blk_stat_callback *cb)
+{
+ return timer_pending(&cb->timer);
+}
+
+/**
+ * blk_stat_activate_nsecs() - Gather block statistics during a time window in
+ * nanoseconds.
+ * @cb: The callback.
+ * @nsecs: Number of nanoseconds to gather statistics for.
+ *
+ * The timer callback will be called when the window expires.
+ */
+static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb,
+ u64 nsecs)
+{
+ mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs));
+}
+
+/**
+ * blk_stat_activate_msecs() - Gather block statistics during a time window in
+ * milliseconds.
+ * @cb: The callback.
+ * @msecs: Number of milliseconds to gather statistics for.
+ *
+ * The timer callback will be called when the window expires.
+ */
+static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb,
+ unsigned int msecs)
+{
+ mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs));
}
#endif
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index c44b321335f3..3f37813ccbaf 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -208,7 +208,7 @@ static ssize_t queue_discard_max_store(struct request_queue *q,
static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
{
- return queue_var_show(queue_discard_zeroes_data(q), page);
+ return queue_var_show(0, page);
}
static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
@@ -503,26 +503,6 @@ static ssize_t queue_dax_show(struct request_queue *q, char *page)
return queue_var_show(blk_queue_dax(q), page);
}
-static ssize_t print_stat(char *page, struct blk_rq_stat *stat, const char *pre)
-{
- return sprintf(page, "%s samples=%llu, mean=%lld, min=%lld, max=%lld\n",
- pre, (long long) stat->nr_samples,
- (long long) stat->mean, (long long) stat->min,
- (long long) stat->max);
-}
-
-static ssize_t queue_stats_show(struct request_queue *q, char *page)
-{
- struct blk_rq_stat stat[2];
- ssize_t ret;
-
- blk_queue_stat_get(q, stat);
-
- ret = print_stat(page, &stat[BLK_STAT_READ], "read :");
- ret += print_stat(page + ret, &stat[BLK_STAT_WRITE], "write:");
- return ret;
-}
-
static struct queue_sysfs_entry queue_requests_entry = {
.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
.show = queue_requests_show,
@@ -691,17 +671,20 @@ static struct queue_sysfs_entry queue_dax_entry = {
.show = queue_dax_show,
};
-static struct queue_sysfs_entry queue_stats_entry = {
- .attr = {.name = "stats", .mode = S_IRUGO },
- .show = queue_stats_show,
-};
-
static struct queue_sysfs_entry queue_wb_lat_entry = {
.attr = {.name = "wbt_lat_usec", .mode = S_IRUGO | S_IWUSR },
.show = queue_wb_lat_show,
.store = queue_wb_lat_store,
};
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+static struct queue_sysfs_entry throtl_sample_time_entry = {
+ .attr = {.name = "throttle_sample_time", .mode = S_IRUGO | S_IWUSR },
+ .show = blk_throtl_sample_time_show,
+ .store = blk_throtl_sample_time_store,
+};
+#endif
+
static struct attribute *default_attrs[] = {
&queue_requests_entry.attr,
&queue_ra_entry.attr,
@@ -733,9 +716,11 @@ static struct attribute *default_attrs[] = {
&queue_poll_entry.attr,
&queue_wc_entry.attr,
&queue_dax_entry.attr,
- &queue_stats_entry.attr,
&queue_wb_lat_entry.attr,
&queue_poll_delay_entry.attr,
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+ &throtl_sample_time_entry.attr,
+#endif
NULL,
};
@@ -810,15 +795,19 @@ static void blk_release_queue(struct kobject *kobj)
struct request_queue *q =
container_of(kobj, struct request_queue, kobj);
- wbt_exit(q);
+ if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
+ blk_stat_remove_callback(q, q->poll_cb);
+ blk_stat_free_callback(q->poll_cb);
bdi_put(q->backing_dev_info);
blkcg_exit_queue(q);
if (q->elevator) {
ioc_clear_queue(q);
- elevator_exit(q->elevator);
+ elevator_exit(q, q->elevator);
}
+ blk_free_queue_stats(q->stats);
+
blk_exit_rl(&q->root_rl);
if (q->queue_tags)
@@ -855,23 +844,6 @@ struct kobj_type blk_queue_ktype = {
.release = blk_release_queue,
};
-static void blk_wb_init(struct request_queue *q)
-{
-#ifndef CONFIG_BLK_WBT_MQ
- if (q->mq_ops)
- return;
-#endif
-#ifndef CONFIG_BLK_WBT_SQ
- if (q->request_fn)
- return;
-#endif
-
- /*
- * If this fails, we don't get throttling
- */
- wbt_init(q);
-}
-
int blk_register_queue(struct gendisk *disk)
{
int ret;
@@ -881,6 +853,11 @@ int blk_register_queue(struct gendisk *disk)
if (WARN_ON(!q))
return -ENXIO;
+ WARN_ONCE(test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags),
+ "%s is registering an already registered queue\n",
+ kobject_name(&dev->kobj));
+ queue_flag_set_unlocked(QUEUE_FLAG_REGISTERED, q);
+
/*
* SCSI probing may synchronously create and destroy a lot of
* request_queues for non-existent devices. Shutting down a fully
@@ -900,9 +877,6 @@ int blk_register_queue(struct gendisk *disk)
if (ret)
return ret;
- if (q->mq_ops)
- blk_mq_register_dev(dev, q);
-
/* Prevent changes through sysfs until registration is completed. */
mutex_lock(&q->sysfs_lock);
@@ -912,9 +886,14 @@ int blk_register_queue(struct gendisk *disk)
goto unlock;
}
+ if (q->mq_ops)
+ __blk_mq_register_dev(dev, q);
+
kobject_uevent(&q->kobj, KOBJ_ADD);
- blk_wb_init(q);
+ wbt_enable_default(q);
+
+ blk_throtl_register_queue(q);
if (q->request_fn || (q->mq_ops && q->elevator)) {
ret = elv_register_queue(q);
@@ -939,6 +918,11 @@ void blk_unregister_queue(struct gendisk *disk)
if (WARN_ON(!q))
return;
+ queue_flag_clear_unlocked(QUEUE_FLAG_REGISTERED, q);
+
+ wbt_exit(q);
+
+
if (q->mq_ops)
blk_mq_unregister_dev(disk_to_dev(disk), q);
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 8fab716e4059..b78db2e5fdff 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -18,8 +18,17 @@ static int throtl_grp_quantum = 8;
/* Total max dispatch from all groups in one round */
static int throtl_quantum = 32;
-/* Throttling is performed over 100ms slice and after that slice is renewed */
-static unsigned long throtl_slice = HZ/10; /* 100 ms */
+/* Throttling is performed over a slice and after that slice is renewed */
+#define DFL_THROTL_SLICE_HD (HZ / 10)
+#define DFL_THROTL_SLICE_SSD (HZ / 50)
+#define MAX_THROTL_SLICE (HZ)
+#define DFL_IDLE_THRESHOLD_SSD (1000L) /* 1 ms */
+#define DFL_IDLE_THRESHOLD_HD (100L * 1000) /* 100 ms */
+#define MAX_IDLE_TIME (5L * 1000 * 1000) /* 5 s */
+/* default latency target is 0, eg, guarantee IO latency by default */
+#define DFL_LATENCY_TARGET (0)
+
+#define SKIP_LATENCY (((u64)1) << BLK_STAT_RES_SHIFT)
static struct blkcg_policy blkcg_policy_throtl;
@@ -83,6 +92,12 @@ enum tg_state_flags {
#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
+enum {
+ LIMIT_LOW,
+ LIMIT_MAX,
+ LIMIT_CNT,
+};
+
struct throtl_grp {
/* must be the first member */
struct blkg_policy_data pd;
@@ -119,20 +134,54 @@ struct throtl_grp {
/* are there any throtl rules between this group and td? */
bool has_rules[2];
- /* bytes per second rate limits */
- uint64_t bps[2];
+ /* internally used bytes per second rate limits */
+ uint64_t bps[2][LIMIT_CNT];
+ /* user configured bps limits */
+ uint64_t bps_conf[2][LIMIT_CNT];
- /* IOPS limits */
- unsigned int iops[2];
+ /* internally used IOPS limits */
+ unsigned int iops[2][LIMIT_CNT];
+ /* user configured IOPS limits */
+ unsigned int iops_conf[2][LIMIT_CNT];
/* Number of bytes disptached in current slice */
uint64_t bytes_disp[2];
/* Number of bio's dispatched in current slice */
unsigned int io_disp[2];
+ unsigned long last_low_overflow_time[2];
+
+ uint64_t last_bytes_disp[2];
+ unsigned int last_io_disp[2];
+
+ unsigned long last_check_time;
+
+ unsigned long latency_target; /* us */
/* When did we start a new slice */
unsigned long slice_start[2];
unsigned long slice_end[2];
+
+ unsigned long last_finish_time; /* ns / 1024 */
+ unsigned long checked_last_finish_time; /* ns / 1024 */
+ unsigned long avg_idletime; /* ns / 1024 */
+ unsigned long idletime_threshold; /* us */
+
+ unsigned int bio_cnt; /* total bios */
+ unsigned int bad_bio_cnt; /* bios exceeding latency threshold */
+ unsigned long bio_cnt_reset_time;
+};
+
+/* We measure latency for request size from <= 4k to >= 1M */
+#define LATENCY_BUCKET_SIZE 9
+
+struct latency_bucket {
+ unsigned long total_latency; /* ns / 1024 */
+ int samples;
+};
+
+struct avg_latency_bucket {
+ unsigned long latency; /* ns / 1024 */
+ bool valid;
};
struct throtl_data
@@ -145,8 +194,26 @@ struct throtl_data
/* Total Number of queued bios on READ and WRITE lists */
unsigned int nr_queued[2];
+ unsigned int throtl_slice;
+
/* Work for dispatching throttled bios */
struct work_struct dispatch_work;
+ unsigned int limit_index;
+ bool limit_valid[LIMIT_CNT];
+
+ unsigned long dft_idletime_threshold; /* us */
+
+ unsigned long low_upgrade_time;
+ unsigned long low_downgrade_time;
+
+ unsigned int scale;
+
+ struct latency_bucket tmp_buckets[LATENCY_BUCKET_SIZE];
+ struct avg_latency_bucket avg_buckets[LATENCY_BUCKET_SIZE];
+ struct latency_bucket __percpu *latency_buckets;
+ unsigned long last_calculate_time;
+
+ bool track_bio_latency;
};
static void throtl_pending_timer_fn(unsigned long arg);
@@ -198,6 +265,76 @@ static struct throtl_data *sq_to_td(struct throtl_service_queue *sq)
return container_of(sq, struct throtl_data, service_queue);
}
+/*
+ * cgroup's limit in LIMIT_MAX is scaled if low limit is set. This scale is to
+ * make the IO dispatch more smooth.
+ * Scale up: linearly scale up according to lapsed time since upgrade. For
+ * every throtl_slice, the limit scales up 1/2 .low limit till the
+ * limit hits .max limit
+ * Scale down: exponentially scale down if a cgroup doesn't hit its .low limit
+ */
+static uint64_t throtl_adjusted_limit(uint64_t low, struct throtl_data *td)
+{
+ /* arbitrary value to avoid too big scale */
+ if (td->scale < 4096 && time_after_eq(jiffies,
+ td->low_upgrade_time + td->scale * td->throtl_slice))
+ td->scale = (jiffies - td->low_upgrade_time) / td->throtl_slice;
+
+ return low + (low >> 1) * td->scale;
+}
+
+static uint64_t tg_bps_limit(struct throtl_grp *tg, int rw)
+{
+ struct blkcg_gq *blkg = tg_to_blkg(tg);
+ struct throtl_data *td;
+ uint64_t ret;
+
+ if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent)
+ return U64_MAX;
+
+ td = tg->td;
+ ret = tg->bps[rw][td->limit_index];
+ if (ret == 0 && td->limit_index == LIMIT_LOW)
+ return tg->bps[rw][LIMIT_MAX];
+
+ if (td->limit_index == LIMIT_MAX && tg->bps[rw][LIMIT_LOW] &&
+ tg->bps[rw][LIMIT_LOW] != tg->bps[rw][LIMIT_MAX]) {
+ uint64_t adjusted;
+
+ adjusted = throtl_adjusted_limit(tg->bps[rw][LIMIT_LOW], td);
+ ret = min(tg->bps[rw][LIMIT_MAX], adjusted);
+ }
+ return ret;
+}
+
+static unsigned int tg_iops_limit(struct throtl_grp *tg, int rw)
+{
+ struct blkcg_gq *blkg = tg_to_blkg(tg);
+ struct throtl_data *td;
+ unsigned int ret;
+
+ if (cgroup_subsys_on_dfl(io_cgrp_subsys) && !blkg->parent)
+ return UINT_MAX;
+ td = tg->td;
+ ret = tg->iops[rw][td->limit_index];
+ if (ret == 0 && tg->td->limit_index == LIMIT_LOW)
+ return tg->iops[rw][LIMIT_MAX];
+
+ if (td->limit_index == LIMIT_MAX && tg->iops[rw][LIMIT_LOW] &&
+ tg->iops[rw][LIMIT_LOW] != tg->iops[rw][LIMIT_MAX]) {
+ uint64_t adjusted;
+
+ adjusted = throtl_adjusted_limit(tg->iops[rw][LIMIT_LOW], td);
+ if (adjusted > UINT_MAX)
+ adjusted = UINT_MAX;
+ ret = min_t(unsigned int, tg->iops[rw][LIMIT_MAX], adjusted);
+ }
+ return ret;
+}
+
+#define request_bucket_index(sectors) \
+ clamp_t(int, order_base_2(sectors) - 3, 0, LATENCY_BUCKET_SIZE - 1)
+
/**
* throtl_log - log debug message via blktrace
* @sq: the service_queue being reported
@@ -334,10 +471,17 @@ static struct blkg_policy_data *throtl_pd_alloc(gfp_t gfp, int node)
}
RB_CLEAR_NODE(&tg->rb_node);
- tg->bps[READ] = -1;
- tg->bps[WRITE] = -1;
- tg->iops[READ] = -1;
- tg->iops[WRITE] = -1;
+ tg->bps[READ][LIMIT_MAX] = U64_MAX;
+ tg->bps[WRITE][LIMIT_MAX] = U64_MAX;
+ tg->iops[READ][LIMIT_MAX] = UINT_MAX;
+ tg->iops[WRITE][LIMIT_MAX] = UINT_MAX;
+ tg->bps_conf[READ][LIMIT_MAX] = U64_MAX;
+ tg->bps_conf[WRITE][LIMIT_MAX] = U64_MAX;
+ tg->iops_conf[READ][LIMIT_MAX] = UINT_MAX;
+ tg->iops_conf[WRITE][LIMIT_MAX] = UINT_MAX;
+ /* LIMIT_LOW will have default value 0 */
+
+ tg->latency_target = DFL_LATENCY_TARGET;
return &tg->pd;
}
@@ -366,6 +510,8 @@ static void throtl_pd_init(struct blkg_policy_data *pd)
if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent)
sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
tg->td = td;
+
+ tg->idletime_threshold = td->dft_idletime_threshold;
}
/*
@@ -376,20 +522,59 @@ static void throtl_pd_init(struct blkg_policy_data *pd)
static void tg_update_has_rules(struct throtl_grp *tg)
{
struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq);
+ struct throtl_data *td = tg->td;
int rw;
for (rw = READ; rw <= WRITE; rw++)
tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) ||
- (tg->bps[rw] != -1 || tg->iops[rw] != -1);
+ (td->limit_valid[td->limit_index] &&
+ (tg_bps_limit(tg, rw) != U64_MAX ||
+ tg_iops_limit(tg, rw) != UINT_MAX));
}
static void throtl_pd_online(struct blkg_policy_data *pd)
{
+ struct throtl_grp *tg = pd_to_tg(pd);
/*
* We don't want new groups to escape the limits of its ancestors.
* Update has_rules[] after a new group is brought online.
*/
- tg_update_has_rules(pd_to_tg(pd));
+ tg_update_has_rules(tg);
+}
+
+static void blk_throtl_update_limit_valid(struct throtl_data *td)
+{
+ struct cgroup_subsys_state *pos_css;
+ struct blkcg_gq *blkg;
+ bool low_valid = false;
+
+ rcu_read_lock();
+ blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+
+ if (tg->bps[READ][LIMIT_LOW] || tg->bps[WRITE][LIMIT_LOW] ||
+ tg->iops[READ][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW])
+ low_valid = true;
+ }
+ rcu_read_unlock();
+
+ td->limit_valid[LIMIT_LOW] = low_valid;
+}
+
+static void throtl_upgrade_state(struct throtl_data *td);
+static void throtl_pd_offline(struct blkg_policy_data *pd)
+{
+ struct throtl_grp *tg = pd_to_tg(pd);
+
+ tg->bps[READ][LIMIT_LOW] = 0;
+ tg->bps[WRITE][LIMIT_LOW] = 0;
+ tg->iops[READ][LIMIT_LOW] = 0;
+ tg->iops[WRITE][LIMIT_LOW] = 0;
+
+ blk_throtl_update_limit_valid(tg->td);
+
+ if (!tg->td->limit_valid[tg->td->limit_index])
+ throtl_upgrade_state(tg->td);
}
static void throtl_pd_free(struct blkg_policy_data *pd)
@@ -499,6 +684,17 @@ static void throtl_dequeue_tg(struct throtl_grp *tg)
static void throtl_schedule_pending_timer(struct throtl_service_queue *sq,
unsigned long expires)
{
+ unsigned long max_expire = jiffies + 8 * sq_to_tg(sq)->td->throtl_slice;
+
+ /*
+ * Since we are adjusting the throttle limit dynamically, the sleep
+ * time calculated according to previous limit might be invalid. It's
+ * possible the cgroup sleep time is very long and no other cgroups
+ * have IO running so notify the limit changes. Make sure the cgroup
+ * doesn't sleep too long to avoid the missed notification.
+ */
+ if (time_after(expires, max_expire))
+ expires = max_expire;
mod_timer(&sq->pending_timer, expires);
throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu",
expires - jiffies, jiffies);
@@ -556,7 +752,7 @@ static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg,
if (time_after_eq(start, tg->slice_start[rw]))
tg->slice_start[rw] = start;
- tg->slice_end[rw] = jiffies + throtl_slice;
+ tg->slice_end[rw] = jiffies + tg->td->throtl_slice;
throtl_log(&tg->service_queue,
"[%c] new slice with credit start=%lu end=%lu jiffies=%lu",
rw == READ ? 'R' : 'W', tg->slice_start[rw],
@@ -568,7 +764,7 @@ static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw)
tg->bytes_disp[rw] = 0;
tg->io_disp[rw] = 0;
tg->slice_start[rw] = jiffies;
- tg->slice_end[rw] = jiffies + throtl_slice;
+ tg->slice_end[rw] = jiffies + tg->td->throtl_slice;
throtl_log(&tg->service_queue,
"[%c] new slice start=%lu end=%lu jiffies=%lu",
rw == READ ? 'R' : 'W', tg->slice_start[rw],
@@ -578,13 +774,13 @@ static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw)
static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw,
unsigned long jiffy_end)
{
- tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
+ tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice);
}
static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw,
unsigned long jiffy_end)
{
- tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
+ tg->slice_end[rw] = roundup(jiffy_end, tg->td->throtl_slice);
throtl_log(&tg->service_queue,
"[%c] extend slice start=%lu end=%lu jiffies=%lu",
rw == READ ? 'R' : 'W', tg->slice_start[rw],
@@ -624,19 +820,20 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
* is bad because it does not allow new slice to start.
*/
- throtl_set_slice_end(tg, rw, jiffies + throtl_slice);
+ throtl_set_slice_end(tg, rw, jiffies + tg->td->throtl_slice);
time_elapsed = jiffies - tg->slice_start[rw];
- nr_slices = time_elapsed / throtl_slice;
+ nr_slices = time_elapsed / tg->td->throtl_slice;
if (!nr_slices)
return;
- tmp = tg->bps[rw] * throtl_slice * nr_slices;
+ tmp = tg_bps_limit(tg, rw) * tg->td->throtl_slice * nr_slices;
do_div(tmp, HZ);
bytes_trim = tmp;
- io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
+ io_trim = (tg_iops_limit(tg, rw) * tg->td->throtl_slice * nr_slices) /
+ HZ;
if (!bytes_trim && !io_trim)
return;
@@ -651,7 +848,7 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
else
tg->io_disp[rw] = 0;
- tg->slice_start[rw] += nr_slices * throtl_slice;
+ tg->slice_start[rw] += nr_slices * tg->td->throtl_slice;
throtl_log(&tg->service_queue,
"[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu",
@@ -671,9 +868,9 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
/* Slice has just started. Consider one slice interval */
if (!jiffy_elapsed)
- jiffy_elapsed_rnd = throtl_slice;
+ jiffy_elapsed_rnd = tg->td->throtl_slice;
- jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
+ jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);
/*
* jiffy_elapsed_rnd should not be a big value as minimum iops can be
@@ -682,7 +879,7 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
* have been trimmed.
*/
- tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd;
+ tmp = (u64)tg_iops_limit(tg, rw) * jiffy_elapsed_rnd;
do_div(tmp, HZ);
if (tmp > UINT_MAX)
@@ -697,7 +894,7 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
}
/* Calc approx time to dispatch */
- jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1;
+ jiffy_wait = ((tg->io_disp[rw] + 1) * HZ) / tg_iops_limit(tg, rw) + 1;
if (jiffy_wait > jiffy_elapsed)
jiffy_wait = jiffy_wait - jiffy_elapsed;
@@ -720,11 +917,11 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
/* Slice has just started. Consider one slice interval */
if (!jiffy_elapsed)
- jiffy_elapsed_rnd = throtl_slice;
+ jiffy_elapsed_rnd = tg->td->throtl_slice;
- jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
+ jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);
- tmp = tg->bps[rw] * jiffy_elapsed_rnd;
+ tmp = tg_bps_limit(tg, rw) * jiffy_elapsed_rnd;
do_div(tmp, HZ);
bytes_allowed = tmp;
@@ -736,7 +933,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
/* Calc approx time to dispatch */
extra_bytes = tg->bytes_disp[rw] + bio->bi_iter.bi_size - bytes_allowed;
- jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
+ jiffy_wait = div64_u64(extra_bytes * HZ, tg_bps_limit(tg, rw));
if (!jiffy_wait)
jiffy_wait = 1;
@@ -771,7 +968,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
bio != throtl_peek_queued(&tg->service_queue.queued[rw]));
/* If tg->bps = -1, then BW is unlimited */
- if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
+ if (tg_bps_limit(tg, rw) == U64_MAX &&
+ tg_iops_limit(tg, rw) == UINT_MAX) {
if (wait)
*wait = 0;
return true;
@@ -787,8 +985,10 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
if (throtl_slice_used(tg, rw) && !(tg->service_queue.nr_queued[rw]))
throtl_start_new_slice(tg, rw);
else {
- if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
- throtl_extend_slice(tg, rw, jiffies + throtl_slice);
+ if (time_before(tg->slice_end[rw],
+ jiffies + tg->td->throtl_slice))
+ throtl_extend_slice(tg, rw,
+ jiffies + tg->td->throtl_slice);
}
if (tg_with_in_bps_limit(tg, bio, &bps_wait) &&
@@ -816,6 +1016,8 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
/* Charge the bio to the group */
tg->bytes_disp[rw] += bio->bi_iter.bi_size;
tg->io_disp[rw]++;
+ tg->last_bytes_disp[rw] += bio->bi_iter.bi_size;
+ tg->last_io_disp[rw]++;
/*
* BIO_THROTTLED is used to prevent the same bio to be throttled
@@ -999,6 +1201,8 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
return nr_disp;
}
+static bool throtl_can_upgrade(struct throtl_data *td,
+ struct throtl_grp *this_tg);
/**
* throtl_pending_timer_fn - timer function for service_queue->pending_timer
* @arg: the throtl_service_queue being serviced
@@ -1025,6 +1229,9 @@ static void throtl_pending_timer_fn(unsigned long arg)
int ret;
spin_lock_irq(q->queue_lock);
+ if (throtl_can_upgrade(td, NULL))
+ throtl_upgrade_state(td);
+
again:
parent_sq = sq->parent_sq;
dispatched = false;
@@ -1112,7 +1319,7 @@ static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd,
struct throtl_grp *tg = pd_to_tg(pd);
u64 v = *(u64 *)((void *)tg + off);
- if (v == -1)
+ if (v == U64_MAX)
return 0;
return __blkg_prfill_u64(sf, pd, v);
}
@@ -1123,7 +1330,7 @@ static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd,
struct throtl_grp *tg = pd_to_tg(pd);
unsigned int v = *(unsigned int *)((void *)tg + off);
- if (v == -1)
+ if (v == UINT_MAX)
return 0;
return __blkg_prfill_u64(sf, pd, v);
}
@@ -1150,8 +1357,8 @@ static void tg_conf_updated(struct throtl_grp *tg)
throtl_log(&tg->service_queue,
"limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
- tg->bps[READ], tg->bps[WRITE],
- tg->iops[READ], tg->iops[WRITE]);
+ tg_bps_limit(tg, READ), tg_bps_limit(tg, WRITE),
+ tg_iops_limit(tg, READ), tg_iops_limit(tg, WRITE));
/*
* Update has_rules[] flags for the updated tg's subtree. A tg is
@@ -1197,7 +1404,7 @@ static ssize_t tg_set_conf(struct kernfs_open_file *of,
if (sscanf(ctx.body, "%llu", &v) != 1)
goto out_finish;
if (!v)
- v = -1;
+ v = U64_MAX;
tg = blkg_to_tg(ctx.blkg);
@@ -1228,25 +1435,25 @@ static ssize_t tg_set_conf_uint(struct kernfs_open_file *of,
static struct cftype throtl_legacy_files[] = {
{
.name = "throttle.read_bps_device",
- .private = offsetof(struct throtl_grp, bps[READ]),
+ .private = offsetof(struct throtl_grp, bps[READ][LIMIT_MAX]),
.seq_show = tg_print_conf_u64,
.write = tg_set_conf_u64,
},
{
.name = "throttle.write_bps_device",
- .private = offsetof(struct throtl_grp, bps[WRITE]),
+ .private = offsetof(struct throtl_grp, bps[WRITE][LIMIT_MAX]),
.seq_show = tg_print_conf_u64,
.write = tg_set_conf_u64,
},
{
.name = "throttle.read_iops_device",
- .private = offsetof(struct throtl_grp, iops[READ]),
+ .private = offsetof(struct throtl_grp, iops[READ][LIMIT_MAX]),
.seq_show = tg_print_conf_uint,
.write = tg_set_conf_uint,
},
{
.name = "throttle.write_iops_device",
- .private = offsetof(struct throtl_grp, iops[WRITE]),
+ .private = offsetof(struct throtl_grp, iops[WRITE][LIMIT_MAX]),
.seq_show = tg_print_conf_uint,
.write = tg_set_conf_uint,
},
@@ -1263,48 +1470,87 @@ static struct cftype throtl_legacy_files[] = {
{ } /* terminate */
};
-static u64 tg_prfill_max(struct seq_file *sf, struct blkg_policy_data *pd,
+static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
int off)
{
struct throtl_grp *tg = pd_to_tg(pd);
const char *dname = blkg_dev_name(pd->blkg);
char bufs[4][21] = { "max", "max", "max", "max" };
+ u64 bps_dft;
+ unsigned int iops_dft;
+ char idle_time[26] = "";
+ char latency_time[26] = "";
if (!dname)
return 0;
- if (tg->bps[READ] == -1 && tg->bps[WRITE] == -1 &&
- tg->iops[READ] == -1 && tg->iops[WRITE] == -1)
+
+ if (off == LIMIT_LOW) {
+ bps_dft = 0;
+ iops_dft = 0;
+ } else {
+ bps_dft = U64_MAX;
+ iops_dft = UINT_MAX;
+ }
+
+ if (tg->bps_conf[READ][off] == bps_dft &&
+ tg->bps_conf[WRITE][off] == bps_dft &&
+ tg->iops_conf[READ][off] == iops_dft &&
+ tg->iops_conf[WRITE][off] == iops_dft &&
+ (off != LIMIT_LOW ||
+ (tg->idletime_threshold == tg->td->dft_idletime_threshold &&
+ tg->latency_target == DFL_LATENCY_TARGET)))
return 0;
- if (tg->bps[READ] != -1)
- snprintf(bufs[0], sizeof(bufs[0]), "%llu", tg->bps[READ]);
- if (tg->bps[WRITE] != -1)
- snprintf(bufs[1], sizeof(bufs[1]), "%llu", tg->bps[WRITE]);
- if (tg->iops[READ] != -1)
- snprintf(bufs[2], sizeof(bufs[2]), "%u", tg->iops[READ]);
- if (tg->iops[WRITE] != -1)
- snprintf(bufs[3], sizeof(bufs[3]), "%u", tg->iops[WRITE]);
-
- seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s\n",
- dname, bufs[0], bufs[1], bufs[2], bufs[3]);
+ if (tg->bps_conf[READ][off] != bps_dft)
+ snprintf(bufs[0], sizeof(bufs[0]), "%llu",
+ tg->bps_conf[READ][off]);
+ if (tg->bps_conf[WRITE][off] != bps_dft)
+ snprintf(bufs[1], sizeof(bufs[1]), "%llu",
+ tg->bps_conf[WRITE][off]);
+ if (tg->iops_conf[READ][off] != iops_dft)
+ snprintf(bufs[2], sizeof(bufs[2]), "%u",
+ tg->iops_conf[READ][off]);
+ if (tg->iops_conf[WRITE][off] != iops_dft)
+ snprintf(bufs[3], sizeof(bufs[3]), "%u",
+ tg->iops_conf[WRITE][off]);
+ if (off == LIMIT_LOW) {
+ if (tg->idletime_threshold == ULONG_MAX)
+ strcpy(idle_time, " idle=max");
+ else
+ snprintf(idle_time, sizeof(idle_time), " idle=%lu",
+ tg->idletime_threshold);
+
+ if (tg->latency_target == ULONG_MAX)
+ strcpy(latency_time, " latency=max");
+ else
+ snprintf(latency_time, sizeof(latency_time),
+ " latency=%lu", tg->latency_target);
+ }
+
+ seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n",
+ dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time,
+ latency_time);
return 0;
}
-static int tg_print_max(struct seq_file *sf, void *v)
+static int tg_print_limit(struct seq_file *sf, void *v)
{
- blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_max,
+ blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), tg_prfill_limit,
&blkcg_policy_throtl, seq_cft(sf)->private, false);
return 0;
}
-static ssize_t tg_set_max(struct kernfs_open_file *of,
+static ssize_t tg_set_limit(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct blkcg *blkcg = css_to_blkcg(of_css(of));
struct blkg_conf_ctx ctx;
struct throtl_grp *tg;
u64 v[4];
+ unsigned long idle_time;
+ unsigned long latency_time;
int ret;
+ int index = of_cft(of)->private;
ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx);
if (ret)
@@ -1312,15 +1558,17 @@ static ssize_t tg_set_max(struct kernfs_open_file *of,
tg = blkg_to_tg(ctx.blkg);
- v[0] = tg->bps[READ];
- v[1] = tg->bps[WRITE];
- v[2] = tg->iops[READ];
- v[3] = tg->iops[WRITE];
+ v[0] = tg->bps_conf[READ][index];
+ v[1] = tg->bps_conf[WRITE][index];
+ v[2] = tg->iops_conf[READ][index];
+ v[3] = tg->iops_conf[WRITE][index];
+ idle_time = tg->idletime_threshold;
+ latency_time = tg->latency_target;
while (true) {
char tok[27]; /* wiops=18446744073709551616 */
char *p;
- u64 val = -1;
+ u64 val = U64_MAX;
int len;
if (sscanf(ctx.body, "%26s%n", tok, &len) != 1)
@@ -1348,15 +1596,43 @@ static ssize_t tg_set_max(struct kernfs_open_file *of,
v[2] = min_t(u64, val, UINT_MAX);
else if (!strcmp(tok, "wiops"))
v[3] = min_t(u64, val, UINT_MAX);
+ else if (off == LIMIT_LOW && !strcmp(tok, "idle"))
+ idle_time = val;
+ else if (off == LIMIT_LOW && !strcmp(tok, "latency"))
+ latency_time = val;
else
goto out_finish;
}
- tg->bps[READ] = v[0];
- tg->bps[WRITE] = v[1];
- tg->iops[READ] = v[2];
- tg->iops[WRITE] = v[3];
+ tg->bps_conf[READ][index] = v[0];
+ tg->bps_conf[WRITE][index] = v[1];
+ tg->iops_conf[READ][index] = v[2];
+ tg->iops_conf[WRITE][index] = v[3];
+ if (index == LIMIT_MAX) {
+ tg->bps[READ][index] = v[0];
+ tg->bps[WRITE][index] = v[1];
+ tg->iops[READ][index] = v[2];
+ tg->iops[WRITE][index] = v[3];
+ }
+ tg->bps[READ][LIMIT_LOW] = min(tg->bps_conf[READ][LIMIT_LOW],
+ tg->bps_conf[READ][LIMIT_MAX]);
+ tg->bps[WRITE][LIMIT_LOW] = min(tg->bps_conf[WRITE][LIMIT_LOW],
+ tg->bps_conf[WRITE][LIMIT_MAX]);
+ tg->iops[READ][LIMIT_LOW] = min(tg->iops_conf[READ][LIMIT_LOW],
+ tg->iops_conf[READ][LIMIT_MAX]);
+ tg->iops[WRITE][LIMIT_LOW] = min(tg->iops_conf[WRITE][LIMIT_LOW],
+ tg->iops_conf[WRITE][LIMIT_MAX]);
+
+ if (index == LIMIT_LOW) {
+ blk_throtl_update_limit_valid(tg->td);
+ if (tg->td->limit_valid[LIMIT_LOW])
+ tg->td->limit_index = LIMIT_LOW;
+ tg->idletime_threshold = (idle_time == ULONG_MAX) ?
+ ULONG_MAX : idle_time;
+ tg->latency_target = (latency_time == ULONG_MAX) ?
+ ULONG_MAX : latency_time;
+ }
tg_conf_updated(tg);
ret = 0;
out_finish:
@@ -1365,11 +1641,21 @@ out_finish:
}
static struct cftype throtl_files[] = {
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+ {
+ .name = "low",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = tg_print_limit,
+ .write = tg_set_limit,
+ .private = LIMIT_LOW,
+ },
+#endif
{
.name = "max",
.flags = CFTYPE_NOT_ON_ROOT,
- .seq_show = tg_print_max,
- .write = tg_set_max,
+ .seq_show = tg_print_limit,
+ .write = tg_set_limit,
+ .private = LIMIT_MAX,
},
{ } /* terminate */
};
@@ -1388,9 +1674,376 @@ static struct blkcg_policy blkcg_policy_throtl = {
.pd_alloc_fn = throtl_pd_alloc,
.pd_init_fn = throtl_pd_init,
.pd_online_fn = throtl_pd_online,
+ .pd_offline_fn = throtl_pd_offline,
.pd_free_fn = throtl_pd_free,
};
+static unsigned long __tg_last_low_overflow_time(struct throtl_grp *tg)
+{
+ unsigned long rtime = jiffies, wtime = jiffies;
+
+ if (tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW])
+ rtime = tg->last_low_overflow_time[READ];
+ if (tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW])
+ wtime = tg->last_low_overflow_time[WRITE];
+ return min(rtime, wtime);
+}
+
+/* tg should not be an intermediate node */
+static unsigned long tg_last_low_overflow_time(struct throtl_grp *tg)
+{
+ struct throtl_service_queue *parent_sq;
+ struct throtl_grp *parent = tg;
+ unsigned long ret = __tg_last_low_overflow_time(tg);
+
+ while (true) {
+ parent_sq = parent->service_queue.parent_sq;
+ parent = sq_to_tg(parent_sq);
+ if (!parent)
+ break;
+
+ /*
+ * The parent doesn't have low limit, it always reaches low
+ * limit. Its overflow time is useless for children
+ */
+ if (!parent->bps[READ][LIMIT_LOW] &&
+ !parent->iops[READ][LIMIT_LOW] &&
+ !parent->bps[WRITE][LIMIT_LOW] &&
+ !parent->iops[WRITE][LIMIT_LOW])
+ continue;
+ if (time_after(__tg_last_low_overflow_time(parent), ret))
+ ret = __tg_last_low_overflow_time(parent);
+ }
+ return ret;
+}
+
+static bool throtl_tg_is_idle(struct throtl_grp *tg)
+{
+ /*
+ * cgroup is idle if:
+ * - single idle is too long, longer than a fixed value (in case user
+ * configure a too big threshold) or 4 times of slice
+ * - average think time is more than threshold
+ * - IO latency is largely below threshold
+ */
+ unsigned long time = jiffies_to_usecs(4 * tg->td->throtl_slice);
+
+ time = min_t(unsigned long, MAX_IDLE_TIME, time);
+ return (ktime_get_ns() >> 10) - tg->last_finish_time > time ||
+ tg->avg_idletime > tg->idletime_threshold ||
+ (tg->latency_target && tg->bio_cnt &&
+ tg->bad_bio_cnt * 5 < tg->bio_cnt);
+}
+
+static bool throtl_tg_can_upgrade(struct throtl_grp *tg)
+{
+ struct throtl_service_queue *sq = &tg->service_queue;
+ bool read_limit, write_limit;
+
+ /*
+ * if cgroup reaches low limit (if low limit is 0, the cgroup always
+ * reaches), it's ok to upgrade to next limit
+ */
+ read_limit = tg->bps[READ][LIMIT_LOW] || tg->iops[READ][LIMIT_LOW];
+ write_limit = tg->bps[WRITE][LIMIT_LOW] || tg->iops[WRITE][LIMIT_LOW];
+ if (!read_limit && !write_limit)
+ return true;
+ if (read_limit && sq->nr_queued[READ] &&
+ (!write_limit || sq->nr_queued[WRITE]))
+ return true;
+ if (write_limit && sq->nr_queued[WRITE] &&
+ (!read_limit || sq->nr_queued[READ]))
+ return true;
+
+ if (time_after_eq(jiffies,
+ tg_last_low_overflow_time(tg) + tg->td->throtl_slice) &&
+ throtl_tg_is_idle(tg))
+ return true;
+ return false;
+}
+
+static bool throtl_hierarchy_can_upgrade(struct throtl_grp *tg)
+{
+ while (true) {
+ if (throtl_tg_can_upgrade(tg))
+ return true;
+ tg = sq_to_tg(tg->service_queue.parent_sq);
+ if (!tg || !tg_to_blkg(tg)->parent)
+ return false;
+ }
+ return false;
+}
+
+static bool throtl_can_upgrade(struct throtl_data *td,
+ struct throtl_grp *this_tg)
+{
+ struct cgroup_subsys_state *pos_css;
+ struct blkcg_gq *blkg;
+
+ if (td->limit_index != LIMIT_LOW)
+ return false;
+
+ if (time_before(jiffies, td->low_downgrade_time + td->throtl_slice))
+ return false;
+
+ rcu_read_lock();
+ blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+
+ if (tg == this_tg)
+ continue;
+ if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children))
+ continue;
+ if (!throtl_hierarchy_can_upgrade(tg)) {
+ rcu_read_unlock();
+ return false;
+ }
+ }
+ rcu_read_unlock();
+ return true;
+}
+
+static void throtl_upgrade_check(struct throtl_grp *tg)
+{
+ unsigned long now = jiffies;
+
+ if (tg->td->limit_index != LIMIT_LOW)
+ return;
+
+ if (time_after(tg->last_check_time + tg->td->throtl_slice, now))
+ return;
+
+ tg->last_check_time = now;
+
+ if (!time_after_eq(now,
+ __tg_last_low_overflow_time(tg) + tg->td->throtl_slice))
+ return;
+
+ if (throtl_can_upgrade(tg->td, NULL))
+ throtl_upgrade_state(tg->td);
+}
+
+static void throtl_upgrade_state(struct throtl_data *td)
+{
+ struct cgroup_subsys_state *pos_css;
+ struct blkcg_gq *blkg;
+
+ td->limit_index = LIMIT_MAX;
+ td->low_upgrade_time = jiffies;
+ td->scale = 0;
+ rcu_read_lock();
+ blkg_for_each_descendant_post(blkg, pos_css, td->queue->root_blkg) {
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+ struct throtl_service_queue *sq = &tg->service_queue;
+
+ tg->disptime = jiffies - 1;
+ throtl_select_dispatch(sq);
+ throtl_schedule_next_dispatch(sq, false);
+ }
+ rcu_read_unlock();
+ throtl_select_dispatch(&td->service_queue);
+ throtl_schedule_next_dispatch(&td->service_queue, false);
+ queue_work(kthrotld_workqueue, &td->dispatch_work);
+}
+
+static void throtl_downgrade_state(struct throtl_data *td, int new)
+{
+ td->scale /= 2;
+
+ if (td->scale) {
+ td->low_upgrade_time = jiffies - td->scale * td->throtl_slice;
+ return;
+ }
+
+ td->limit_index = new;
+ td->low_downgrade_time = jiffies;
+}
+
+static bool throtl_tg_can_downgrade(struct throtl_grp *tg)
+{
+ struct throtl_data *td = tg->td;
+ unsigned long now = jiffies;
+
+ /*
+ * If cgroup is below low limit, consider downgrade and throttle other
+ * cgroups
+ */
+ if (time_after_eq(now, td->low_upgrade_time + td->throtl_slice) &&
+ time_after_eq(now, tg_last_low_overflow_time(tg) +
+ td->throtl_slice) &&
+ (!throtl_tg_is_idle(tg) ||
+ !list_empty(&tg_to_blkg(tg)->blkcg->css.children)))
+ return true;
+ return false;
+}
+
+static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg)
+{
+ while (true) {
+ if (!throtl_tg_can_downgrade(tg))
+ return false;
+ tg = sq_to_tg(tg->service_queue.parent_sq);
+ if (!tg || !tg_to_blkg(tg)->parent)
+ break;
+ }
+ return true;
+}
+
+static void throtl_downgrade_check(struct throtl_grp *tg)
+{
+ uint64_t bps;
+ unsigned int iops;
+ unsigned long elapsed_time;
+ unsigned long now = jiffies;
+
+ if (tg->td->limit_index != LIMIT_MAX ||
+ !tg->td->limit_valid[LIMIT_LOW])
+ return;
+ if (!list_empty(&tg_to_blkg(tg)->blkcg->css.children))
+ return;
+ if (time_after(tg->last_check_time + tg->td->throtl_slice, now))
+ return;
+
+ elapsed_time = now - tg->last_check_time;
+ tg->last_check_time = now;
+
+ if (time_before(now, tg_last_low_overflow_time(tg) +
+ tg->td->throtl_slice))
+ return;
+
+ if (tg->bps[READ][LIMIT_LOW]) {
+ bps = tg->last_bytes_disp[READ] * HZ;
+ do_div(bps, elapsed_time);
+ if (bps >= tg->bps[READ][LIMIT_LOW])
+ tg->last_low_overflow_time[READ] = now;
+ }
+
+ if (tg->bps[WRITE][LIMIT_LOW]) {
+ bps = tg->last_bytes_disp[WRITE] * HZ;
+ do_div(bps, elapsed_time);
+ if (bps >= tg->bps[WRITE][LIMIT_LOW])
+ tg->last_low_overflow_time[WRITE] = now;
+ }
+
+ if (tg->iops[READ][LIMIT_LOW]) {
+ iops = tg->last_io_disp[READ] * HZ / elapsed_time;
+ if (iops >= tg->iops[READ][LIMIT_LOW])
+ tg->last_low_overflow_time[READ] = now;
+ }
+
+ if (tg->iops[WRITE][LIMIT_LOW]) {
+ iops = tg->last_io_disp[WRITE] * HZ / elapsed_time;
+ if (iops >= tg->iops[WRITE][LIMIT_LOW])
+ tg->last_low_overflow_time[WRITE] = now;
+ }
+
+ /*
+ * If cgroup is below low limit, consider downgrade and throttle other
+ * cgroups
+ */
+ if (throtl_hierarchy_can_downgrade(tg))
+ throtl_downgrade_state(tg->td, LIMIT_LOW);
+
+ tg->last_bytes_disp[READ] = 0;
+ tg->last_bytes_disp[WRITE] = 0;
+ tg->last_io_disp[READ] = 0;
+ tg->last_io_disp[WRITE] = 0;
+}
+
+static void blk_throtl_update_idletime(struct throtl_grp *tg)
+{
+ unsigned long now = ktime_get_ns() >> 10;
+ unsigned long last_finish_time = tg->last_finish_time;
+
+ if (now <= last_finish_time || last_finish_time == 0 ||
+ last_finish_time == tg->checked_last_finish_time)
+ return;
+
+ tg->avg_idletime = (tg->avg_idletime * 7 + now - last_finish_time) >> 3;
+ tg->checked_last_finish_time = last_finish_time;
+}
+
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+static void throtl_update_latency_buckets(struct throtl_data *td)
+{
+ struct avg_latency_bucket avg_latency[LATENCY_BUCKET_SIZE];
+ int i, cpu;
+ unsigned long last_latency = 0;
+ unsigned long latency;
+
+ if (!blk_queue_nonrot(td->queue))
+ return;
+ if (time_before(jiffies, td->last_calculate_time + HZ))
+ return;
+ td->last_calculate_time = jiffies;
+
+ memset(avg_latency, 0, sizeof(avg_latency));
+ for (i = 0; i < LATENCY_BUCKET_SIZE; i++) {
+ struct latency_bucket *tmp = &td->tmp_buckets[i];
+
+ for_each_possible_cpu(cpu) {
+ struct latency_bucket *bucket;
+
+ /* this isn't race free, but ok in practice */
+ bucket = per_cpu_ptr(td->latency_buckets, cpu);
+ tmp->total_latency += bucket[i].total_latency;
+ tmp->samples += bucket[i].samples;
+ bucket[i].total_latency = 0;
+ bucket[i].samples = 0;
+ }
+
+ if (tmp->samples >= 32) {
+ int samples = tmp->samples;
+
+ latency = tmp->total_latency;
+
+ tmp->total_latency = 0;
+ tmp->samples = 0;
+ latency /= samples;
+ if (latency == 0)
+ continue;
+ avg_latency[i].latency = latency;
+ }
+ }
+
+ for (i = 0; i < LATENCY_BUCKET_SIZE; i++) {
+ if (!avg_latency[i].latency) {
+ if (td->avg_buckets[i].latency < last_latency)
+ td->avg_buckets[i].latency = last_latency;
+ continue;
+ }
+
+ if (!td->avg_buckets[i].valid)
+ latency = avg_latency[i].latency;
+ else
+ latency = (td->avg_buckets[i].latency * 7 +
+ avg_latency[i].latency) >> 3;
+
+ td->avg_buckets[i].latency = max(latency, last_latency);
+ td->avg_buckets[i].valid = true;
+ last_latency = td->avg_buckets[i].latency;
+ }
+}
+#else
+static inline void throtl_update_latency_buckets(struct throtl_data *td)
+{
+}
+#endif
+
+static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio)
+{
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+ int ret;
+
+ ret = bio_associate_current(bio);
+ if (ret == 0 || ret == -EBUSY)
+ bio->bi_cg_private = tg;
+ blk_stat_set_issue(&bio->bi_issue_stat, bio_sectors(bio));
+#else
+ bio_associate_current(bio);
+#endif
+}
+
bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
struct bio *bio)
{
@@ -1399,6 +2052,7 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
struct throtl_service_queue *sq;
bool rw = bio_data_dir(bio);
bool throttled = false;
+ struct throtl_data *td = tg->td;
WARN_ON_ONCE(!rcu_read_lock_held());
@@ -1408,19 +2062,35 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
spin_lock_irq(q->queue_lock);
+ throtl_update_latency_buckets(td);
+
if (unlikely(blk_queue_bypass(q)))
goto out_unlock;
+ blk_throtl_assoc_bio(tg, bio);
+ blk_throtl_update_idletime(tg);
+
sq = &tg->service_queue;
+again:
while (true) {
+ if (tg->last_low_overflow_time[rw] == 0)
+ tg->last_low_overflow_time[rw] = jiffies;
+ throtl_downgrade_check(tg);
+ throtl_upgrade_check(tg);
/* throtl is FIFO - if bios are already queued, should queue */
if (sq->nr_queued[rw])
break;
/* if above limits, break to queue */
- if (!tg_may_dispatch(tg, bio, NULL))
+ if (!tg_may_dispatch(tg, bio, NULL)) {
+ tg->last_low_overflow_time[rw] = jiffies;
+ if (throtl_can_upgrade(td, tg)) {
+ throtl_upgrade_state(td);
+ goto again;
+ }
break;
+ }
/* within limits, let's charge and dispatch directly */
throtl_charge_bio(tg, bio);
@@ -1453,12 +2123,14 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
/* out-of-limit, queue to @tg */
throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d",
rw == READ ? 'R' : 'W',
- tg->bytes_disp[rw], bio->bi_iter.bi_size, tg->bps[rw],
- tg->io_disp[rw], tg->iops[rw],
+ tg->bytes_disp[rw], bio->bi_iter.bi_size,
+ tg_bps_limit(tg, rw),
+ tg->io_disp[rw], tg_iops_limit(tg, rw),
sq->nr_queued[READ], sq->nr_queued[WRITE]);
- bio_associate_current(bio);
- tg->td->nr_queued[rw]++;
+ tg->last_low_overflow_time[rw] = jiffies;
+
+ td->nr_queued[rw]++;
throtl_add_bio_tg(bio, qn, tg);
throttled = true;
@@ -1483,9 +2155,94 @@ out:
*/
if (!throttled)
bio_clear_flag(bio, BIO_THROTTLED);
+
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+ if (throttled || !td->track_bio_latency)
+ bio->bi_issue_stat.stat |= SKIP_LATENCY;
+#endif
return throttled;
}
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+static void throtl_track_latency(struct throtl_data *td, sector_t size,
+ int op, unsigned long time)
+{
+ struct latency_bucket *latency;
+ int index;
+
+ if (!td || td->limit_index != LIMIT_LOW || op != REQ_OP_READ ||
+ !blk_queue_nonrot(td->queue))
+ return;
+
+ index = request_bucket_index(size);
+
+ latency = get_cpu_ptr(td->latency_buckets);
+ latency[index].total_latency += time;
+ latency[index].samples++;
+ put_cpu_ptr(td->latency_buckets);
+}
+
+void blk_throtl_stat_add(struct request *rq, u64 time_ns)
+{
+ struct request_queue *q = rq->q;
+ struct throtl_data *td = q->td;
+
+ throtl_track_latency(td, blk_stat_size(&rq->issue_stat),
+ req_op(rq), time_ns >> 10);
+}
+
+void blk_throtl_bio_endio(struct bio *bio)
+{
+ struct throtl_grp *tg;
+ u64 finish_time_ns;
+ unsigned long finish_time;
+ unsigned long start_time;
+ unsigned long lat;
+
+ tg = bio->bi_cg_private;
+ if (!tg)
+ return;
+ bio->bi_cg_private = NULL;
+
+ finish_time_ns = ktime_get_ns();
+ tg->last_finish_time = finish_time_ns >> 10;
+
+ start_time = blk_stat_time(&bio->bi_issue_stat) >> 10;
+ finish_time = __blk_stat_time(finish_time_ns) >> 10;
+ if (!start_time || finish_time <= start_time)
+ return;
+
+ lat = finish_time - start_time;
+ /* this is only for bio based driver */
+ if (!(bio->bi_issue_stat.stat & SKIP_LATENCY))
+ throtl_track_latency(tg->td, blk_stat_size(&bio->bi_issue_stat),
+ bio_op(bio), lat);
+
+ if (tg->latency_target) {
+ int bucket;
+ unsigned int threshold;
+
+ bucket = request_bucket_index(
+ blk_stat_size(&bio->bi_issue_stat));
+ threshold = tg->td->avg_buckets[bucket].latency +
+ tg->latency_target;
+ if (lat > threshold)
+ tg->bad_bio_cnt++;
+ /*
+ * Not race free, could get wrong count, which means cgroups
+ * will be throttled
+ */
+ tg->bio_cnt++;
+ }
+
+ if (time_after(jiffies, tg->bio_cnt_reset_time) || tg->bio_cnt > 1024) {
+ tg->bio_cnt_reset_time = tg->td->throtl_slice + jiffies;
+ tg->bio_cnt /= 2;
+ tg->bad_bio_cnt /= 2;
+ }
+}
+#endif
+
/*
* Dispatch all bios from all children tg's queued on @parent_sq. On
* return, @parent_sq is guaranteed to not have any active children tg's
@@ -1558,6 +2315,12 @@ int blk_throtl_init(struct request_queue *q)
td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
if (!td)
return -ENOMEM;
+ td->latency_buckets = __alloc_percpu(sizeof(struct latency_bucket) *
+ LATENCY_BUCKET_SIZE, __alignof__(u64));
+ if (!td->latency_buckets) {
+ kfree(td);
+ return -ENOMEM;
+ }
INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);
throtl_service_queue_init(&td->service_queue);
@@ -1565,10 +2328,17 @@ int blk_throtl_init(struct request_queue *q)
q->td = td;
td->queue = q;
+ td->limit_valid[LIMIT_MAX] = true;
+ td->limit_index = LIMIT_MAX;
+ td->low_upgrade_time = jiffies;
+ td->low_downgrade_time = jiffies;
+
/* activate policy */
ret = blkcg_activate_policy(q, &blkcg_policy_throtl);
- if (ret)
+ if (ret) {
+ free_percpu(td->latency_buckets);
kfree(td);
+ }
return ret;
}
@@ -1577,9 +2347,74 @@ void blk_throtl_exit(struct request_queue *q)
BUG_ON(!q->td);
throtl_shutdown_wq(q);
blkcg_deactivate_policy(q, &blkcg_policy_throtl);
+ free_percpu(q->td->latency_buckets);
kfree(q->td);
}
+void blk_throtl_register_queue(struct request_queue *q)
+{
+ struct throtl_data *td;
+ struct cgroup_subsys_state *pos_css;
+ struct blkcg_gq *blkg;
+
+ td = q->td;
+ BUG_ON(!td);
+
+ if (blk_queue_nonrot(q)) {
+ td->throtl_slice = DFL_THROTL_SLICE_SSD;
+ td->dft_idletime_threshold = DFL_IDLE_THRESHOLD_SSD;
+ } else {
+ td->throtl_slice = DFL_THROTL_SLICE_HD;
+ td->dft_idletime_threshold = DFL_IDLE_THRESHOLD_HD;
+ }
+#ifndef CONFIG_BLK_DEV_THROTTLING_LOW
+ /* if no low limit, use previous default */
+ td->throtl_slice = DFL_THROTL_SLICE_HD;
+#endif
+
+ td->track_bio_latency = !q->mq_ops && !q->request_fn;
+ if (!td->track_bio_latency)
+ blk_stat_enable_accounting(q);
+
+ /*
+ * some tg are created before queue is fully initialized, eg, nonrot
+ * isn't initialized yet
+ */
+ rcu_read_lock();
+ blkg_for_each_descendant_post(blkg, pos_css, q->root_blkg) {
+ struct throtl_grp *tg = blkg_to_tg(blkg);
+
+ tg->idletime_threshold = td->dft_idletime_threshold;
+ }
+ rcu_read_unlock();
+}
+
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page)
+{
+ if (!q->td)
+ return -EINVAL;
+ return sprintf(page, "%u\n", jiffies_to_msecs(q->td->throtl_slice));
+}
+
+ssize_t blk_throtl_sample_time_store(struct request_queue *q,
+ const char *page, size_t count)
+{
+ unsigned long v;
+ unsigned long t;
+
+ if (!q->td)
+ return -EINVAL;
+ if (kstrtoul(page, 10, &v))
+ return -EINVAL;
+ t = msecs_to_jiffies(v);
+ if (t == 0 || t > MAX_THROTL_SLICE)
+ return -EINVAL;
+ q->td->throtl_slice = t;
+ return count;
+}
+#endif
+
static int __init throtl_init(void)
{
kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index a30441a200c0..cbff183f3d9f 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -89,7 +89,6 @@ static void blk_rq_timed_out(struct request *req)
ret = q->rq_timed_out_fn(req);
switch (ret) {
case BLK_EH_HANDLED:
- /* Can we use req->errors here? */
__blk_complete_request(req);
break;
case BLK_EH_RESET_TIMER:
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 1aedb1f7ee0c..17676f4d7fd1 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -255,8 +255,8 @@ static inline bool stat_sample_valid(struct blk_rq_stat *stat)
* that it's writes impacting us, and not just some sole read on
* a device that is in a lower power state.
*/
- return stat[BLK_STAT_READ].nr_samples >= 1 &&
- stat[BLK_STAT_WRITE].nr_samples >= RWB_MIN_WRITE_SAMPLES;
+ return (stat[READ].nr_samples >= 1 &&
+ stat[WRITE].nr_samples >= RWB_MIN_WRITE_SAMPLES);
}
static u64 rwb_sync_issue_lat(struct rq_wb *rwb)
@@ -277,7 +277,7 @@ enum {
LAT_EXCEEDED,
};
-static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
+static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
{
struct backing_dev_info *bdi = rwb->queue->backing_dev_info;
u64 thislat;
@@ -293,7 +293,7 @@ static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
*/
thislat = rwb_sync_issue_lat(rwb);
if (thislat > rwb->cur_win_nsec ||
- (thislat > rwb->min_lat_nsec && !stat[BLK_STAT_READ].nr_samples)) {
+ (thislat > rwb->min_lat_nsec && !stat[READ].nr_samples)) {
trace_wbt_lat(bdi, thislat);
return LAT_EXCEEDED;
}
@@ -308,8 +308,8 @@ static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
* waited or still has writes in flights, consider us doing
* just writes as well.
*/
- if ((stat[BLK_STAT_WRITE].nr_samples && blk_stat_is_current(stat)) ||
- wb_recent_wait(rwb) || wbt_inflight(rwb))
+ if (stat[WRITE].nr_samples || wb_recent_wait(rwb) ||
+ wbt_inflight(rwb))
return LAT_UNKNOWN_WRITES;
return LAT_UNKNOWN;
}
@@ -317,8 +317,8 @@ static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
/*
* If the 'min' latency exceeds our target, step down.
*/
- if (stat[BLK_STAT_READ].min > rwb->min_lat_nsec) {
- trace_wbt_lat(bdi, stat[BLK_STAT_READ].min);
+ if (stat[READ].min > rwb->min_lat_nsec) {
+ trace_wbt_lat(bdi, stat[READ].min);
trace_wbt_stat(bdi, stat);
return LAT_EXCEEDED;
}
@@ -329,14 +329,6 @@ static int __latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
return LAT_OK;
}
-static int latency_exceeded(struct rq_wb *rwb)
-{
- struct blk_rq_stat stat[2];
-
- blk_queue_stat_get(rwb->queue, stat);
- return __latency_exceeded(rwb, stat);
-}
-
static void rwb_trace_step(struct rq_wb *rwb, const char *msg)
{
struct backing_dev_info *bdi = rwb->queue->backing_dev_info;
@@ -355,7 +347,6 @@ static void scale_up(struct rq_wb *rwb)
rwb->scale_step--;
rwb->unknown_cnt = 0;
- blk_stat_clear(rwb->queue);
rwb->scaled_max = calc_wb_limits(rwb);
@@ -385,15 +376,12 @@ static void scale_down(struct rq_wb *rwb, bool hard_throttle)
rwb->scaled_max = false;
rwb->unknown_cnt = 0;
- blk_stat_clear(rwb->queue);
calc_wb_limits(rwb);
rwb_trace_step(rwb, "step down");
}
static void rwb_arm_timer(struct rq_wb *rwb)
{
- unsigned long expires;
-
if (rwb->scale_step > 0) {
/*
* We should speed this up, using some variant of a fast
@@ -411,17 +399,16 @@ static void rwb_arm_timer(struct rq_wb *rwb)
rwb->cur_win_nsec = rwb->win_nsec;
}
- expires = jiffies + nsecs_to_jiffies(rwb->cur_win_nsec);
- mod_timer(&rwb->window_timer, expires);
+ blk_stat_activate_nsecs(rwb->cb, rwb->cur_win_nsec);
}
-static void wb_timer_fn(unsigned long data)
+static void wb_timer_fn(struct blk_stat_callback *cb)
{
- struct rq_wb *rwb = (struct rq_wb *) data;
+ struct rq_wb *rwb = cb->data;
unsigned int inflight = wbt_inflight(rwb);
int status;
- status = latency_exceeded(rwb);
+ status = latency_exceeded(rwb, cb->stat);
trace_wbt_timer(rwb->queue->backing_dev_info, status, rwb->scale_step,
inflight);
@@ -614,7 +601,7 @@ enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock)
__wbt_wait(rwb, bio->bi_opf, lock);
- if (!timer_pending(&rwb->window_timer))
+ if (!blk_stat_is_active(rwb->cb))
rwb_arm_timer(rwb);
if (current_is_kswapd())
@@ -666,22 +653,37 @@ void wbt_set_write_cache(struct rq_wb *rwb, bool write_cache_on)
rwb->wc = write_cache_on;
}
- /*
- * Disable wbt, if enabled by default. Only called from CFQ, if we have
- * cgroups enabled
+/*
+ * Disable wbt, if enabled by default. Only called from CFQ.
*/
void wbt_disable_default(struct request_queue *q)
{
struct rq_wb *rwb = q->rq_wb;
- if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT) {
- del_timer_sync(&rwb->window_timer);
- rwb->win_nsec = rwb->min_lat_nsec = 0;
- wbt_update_limits(rwb);
- }
+ if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT)
+ wbt_exit(q);
}
EXPORT_SYMBOL_GPL(wbt_disable_default);
+/*
+ * Enable wbt if defaults are configured that way
+ */
+void wbt_enable_default(struct request_queue *q)
+{
+ /* Throttling already enabled? */
+ if (q->rq_wb)
+ return;
+
+ /* Queue not registered? Maybe shutting down... */
+ if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
+ return;
+
+ if ((q->mq_ops && IS_ENABLED(CONFIG_BLK_WBT_MQ)) ||
+ (q->request_fn && IS_ENABLED(CONFIG_BLK_WBT_SQ)))
+ wbt_init(q);
+}
+EXPORT_SYMBOL_GPL(wbt_enable_default);
+
u64 wbt_default_latency_nsec(struct request_queue *q)
{
/*
@@ -694,29 +696,33 @@ u64 wbt_default_latency_nsec(struct request_queue *q)
return 75000000ULL;
}
+static int wbt_data_dir(const struct request *rq)
+{
+ return rq_data_dir(rq);
+}
+
int wbt_init(struct request_queue *q)
{
struct rq_wb *rwb;
int i;
- /*
- * For now, we depend on the stats window being larger than
- * our monitoring window. Ensure that this isn't inadvertently
- * violated.
- */
- BUILD_BUG_ON(RWB_WINDOW_NSEC > BLK_STAT_NSEC);
BUILD_BUG_ON(WBT_NR_BITS > BLK_STAT_RES_BITS);
rwb = kzalloc(sizeof(*rwb), GFP_KERNEL);
if (!rwb)
return -ENOMEM;
+ rwb->cb = blk_stat_alloc_callback(wb_timer_fn, wbt_data_dir, 2, rwb);
+ if (!rwb->cb) {
+ kfree(rwb);
+ return -ENOMEM;
+ }
+
for (i = 0; i < WBT_NUM_RWQ; i++) {
atomic_set(&rwb->rq_wait[i].inflight, 0);
init_waitqueue_head(&rwb->rq_wait[i].wait);
}
- setup_timer(&rwb->window_timer, wb_timer_fn, (unsigned long) rwb);
rwb->wc = 1;
rwb->queue_depth = RWB_DEF_DEPTH;
rwb->last_comp = rwb->last_issue = jiffies;
@@ -726,10 +732,10 @@ int wbt_init(struct request_queue *q)
wbt_update_limits(rwb);
/*
- * Assign rwb, and turn on stats tracking for this queue
+ * Assign rwb and add the stats callback.
*/
q->rq_wb = rwb;
- blk_stat_enable(q);
+ blk_stat_add_callback(q, rwb->cb);
rwb->min_lat_nsec = wbt_default_latency_nsec(q);
@@ -744,7 +750,8 @@ void wbt_exit(struct request_queue *q)
struct rq_wb *rwb = q->rq_wb;
if (rwb) {
- del_timer_sync(&rwb->window_timer);
+ blk_stat_remove_callback(q, rwb->cb);
+ blk_stat_free_callback(rwb->cb);
q->rq_wb = NULL;
kfree(rwb);
}
diff --git a/block/blk-wbt.h b/block/blk-wbt.h
index 65f1de519f67..df6de50c5d59 100644
--- a/block/blk-wbt.h
+++ b/block/blk-wbt.h
@@ -32,27 +32,27 @@ enum {
static inline void wbt_clear_state(struct blk_issue_stat *stat)
{
- stat->time &= BLK_STAT_TIME_MASK;
+ stat->stat &= ~BLK_STAT_RES_MASK;
}
static inline enum wbt_flags wbt_stat_to_mask(struct blk_issue_stat *stat)
{
- return (stat->time & BLK_STAT_MASK) >> BLK_STAT_SHIFT;
+ return (stat->stat & BLK_STAT_RES_MASK) >> BLK_STAT_RES_SHIFT;
}
static inline void wbt_track(struct blk_issue_stat *stat, enum wbt_flags wb_acct)
{
- stat->time |= ((u64) wb_acct) << BLK_STAT_SHIFT;
+ stat->stat |= ((u64) wb_acct) << BLK_STAT_RES_SHIFT;
}
static inline bool wbt_is_tracked(struct blk_issue_stat *stat)
{
- return (stat->time >> BLK_STAT_SHIFT) & WBT_TRACKED;
+ return (stat->stat >> BLK_STAT_RES_SHIFT) & WBT_TRACKED;
}
static inline bool wbt_is_read(struct blk_issue_stat *stat)
{
- return (stat->time >> BLK_STAT_SHIFT) & WBT_READ;
+ return (stat->stat >> BLK_STAT_RES_SHIFT) & WBT_READ;
}
struct rq_wait {
@@ -81,7 +81,7 @@ struct rq_wb {
u64 win_nsec; /* default window size */
u64 cur_win_nsec; /* current window size */
- struct timer_list window_timer;
+ struct blk_stat_callback *cb;
s64 sync_issue;
void *sync_cookie;
@@ -117,6 +117,7 @@ void wbt_update_limits(struct rq_wb *);
void wbt_requeue(struct rq_wb *, struct blk_issue_stat *);
void wbt_issue(struct rq_wb *, struct blk_issue_stat *);
void wbt_disable_default(struct request_queue *);
+void wbt_enable_default(struct request_queue *);
void wbt_set_queue_depth(struct rq_wb *, unsigned int);
void wbt_set_write_cache(struct rq_wb *, bool);
@@ -155,6 +156,9 @@ static inline void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat)
static inline void wbt_disable_default(struct request_queue *q)
{
}
+static inline void wbt_enable_default(struct request_queue *q)
+{
+}
static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
{
}
diff --git a/block/blk.h b/block/blk.h
index d1ea4bd9b9a3..2ed70228e44f 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -60,15 +60,12 @@ void blk_free_flush_queue(struct blk_flush_queue *q);
int blk_init_rl(struct request_list *rl, struct request_queue *q,
gfp_t gfp_mask);
void blk_exit_rl(struct request_list *rl);
-void init_request_from_bio(struct request *req, struct bio *bio);
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
struct bio *bio);
void blk_queue_bypass_start(struct request_queue *q);
void blk_queue_bypass_end(struct request_queue *q);
void blk_dequeue_request(struct request *rq);
void __blk_queue_free_tags(struct request_queue *q);
-bool __blk_end_bidi_request(struct request *rq, int error,
- unsigned int nr_bytes, unsigned int bidi_bytes);
void blk_freeze_queue(struct request_queue *q);
static inline void blk_queue_enter_live(struct request_queue *q)
@@ -319,10 +316,22 @@ static inline struct io_context *create_io_context(gfp_t gfp_mask, int node)
extern void blk_throtl_drain(struct request_queue *q);
extern int blk_throtl_init(struct request_queue *q);
extern void blk_throtl_exit(struct request_queue *q);
+extern void blk_throtl_register_queue(struct request_queue *q);
#else /* CONFIG_BLK_DEV_THROTTLING */
static inline void blk_throtl_drain(struct request_queue *q) { }
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline void blk_throtl_exit(struct request_queue *q) { }
+static inline void blk_throtl_register_queue(struct request_queue *q) { }
#endif /* CONFIG_BLK_DEV_THROTTLING */
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
+extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);
+extern ssize_t blk_throtl_sample_time_store(struct request_queue *q,
+ const char *page, size_t count);
+extern void blk_throtl_bio_endio(struct bio *bio);
+extern void blk_throtl_stat_add(struct request *rq, u64 time);
+#else
+static inline void blk_throtl_bio_endio(struct bio *bio) { }
+static inline void blk_throtl_stat_add(struct request *rq, u64 time) { }
+#endif
#endif /* BLK_INTERNAL_H */
diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index cd15f9dbb147..0a23dbba2d30 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -37,7 +37,7 @@ static void bsg_destroy_job(struct kref *kref)
struct bsg_job *job = container_of(kref, struct bsg_job, kref);
struct request *rq = job->req;
- blk_end_request_all(rq, rq->errors);
+ blk_end_request_all(rq, scsi_req(rq)->result);
put_device(job->dev); /* release reference for the request */
@@ -74,7 +74,7 @@ void bsg_job_done(struct bsg_job *job, int result,
struct scsi_request *rq = scsi_req(req);
int err;
- err = job->req->errors = result;
+ err = scsi_req(job->req)->result = result;
if (err < 0)
/* we're only returning the result field in the reply */
rq->sense_len = sizeof(u32);
@@ -177,7 +177,7 @@ failjob_rls_job:
* @q: request queue to manage
*
* On error the create_bsg_job function should return a -Exyz error value
- * that will be set to the req->errors.
+ * that will be set to ->result.
*
* Drivers/subsys should pass this to the queue init function.
*/
@@ -201,7 +201,7 @@ static void bsg_request_fn(struct request_queue *q)
ret = bsg_create_job(dev, req);
if (ret) {
- req->errors = ret;
+ scsi_req(req)->result = ret;
blk_end_request_all(req, ret);
spin_lock_irq(q->queue_lock);
continue;
diff --git a/block/bsg.c b/block/bsg.c
index 74835dbf0c47..6fd08544d77e 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -391,13 +391,13 @@ static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
struct scsi_request *req = scsi_req(rq);
int ret = 0;
- dprintk("rq %p bio %p 0x%x\n", rq, bio, rq->errors);
+ dprintk("rq %p bio %p 0x%x\n", rq, bio, req->result);
/*
* fill in all the output members
*/
- hdr->device_status = rq->errors & 0xff;
- hdr->transport_status = host_byte(rq->errors);
- hdr->driver_status = driver_byte(rq->errors);
+ hdr->device_status = req->result & 0xff;
+ hdr->transport_status = host_byte(req->result);
+ hdr->driver_status = driver_byte(req->result);
hdr->info = 0;
if (hdr->device_status || hdr->transport_status || hdr->driver_status)
hdr->info |= SG_INFO_CHECK;
@@ -431,8 +431,8 @@ static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
* just a protocol response (i.e. non negative), that gets
* processed above.
*/
- if (!ret && rq->errors < 0)
- ret = rq->errors;
+ if (!ret && req->result < 0)
+ ret = req->result;
blk_rq_unmap_user(bio);
scsi_req_free_cmd(req);
@@ -650,7 +650,7 @@ bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
dprintk("%s: write %zd bytes\n", bd->name, count);
- if (unlikely(segment_eq(get_fs(), KERNEL_DS)))
+ if (unlikely(uaccess_kernel()))
return -EINVAL;
bsg_set_block(bd, file);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 440b95ee593c..da69b079725f 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3761,16 +3761,14 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
-static bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
+static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
{
struct cfq_data *cfqd = cic_to_cfqd(cic);
struct cfq_queue *cfqq;
uint64_t serial_nr;
- bool nonroot_cg;
rcu_read_lock();
serial_nr = bio_blkcg(bio)->css.serial_nr;
- nonroot_cg = bio_blkcg(bio) != &blkcg_root;
rcu_read_unlock();
/*
@@ -3778,7 +3776,7 @@ static bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
* spuriously on a newly created cic but there's no harm.
*/
if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
- return nonroot_cg;
+ return;
/*
* Drop reference to queues. New queues will be assigned in new
@@ -3799,12 +3797,10 @@ static bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
}
cic->blkcg_serial_nr = serial_nr;
- return nonroot_cg;
}
#else
-static inline bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
+static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
{
- return false;
}
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
@@ -4449,12 +4445,11 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
const int rw = rq_data_dir(rq);
const bool is_sync = rq_is_sync(rq);
struct cfq_queue *cfqq;
- bool disable_wbt;
spin_lock_irq(q->queue_lock);
check_ioprio_changed(cic, bio);
- disable_wbt = check_blkcg_changed(cic, bio);
+ check_blkcg_changed(cic, bio);
new_queue:
cfqq = cic_to_cfqq(cic, is_sync);
if (!cfqq || cfqq == &cfqd->oom_cfqq) {
@@ -4491,9 +4486,6 @@ new_queue:
rq->elv.priv[1] = cfqq->cfqg;
spin_unlock_irq(q->queue_lock);
- if (disable_wbt)
- wbt_disable_default(q);
-
return 0;
}
@@ -4706,6 +4698,7 @@ static void cfq_registered_queue(struct request_queue *q)
*/
if (blk_queue_nonrot(q))
cfqd->cfq_slice_idle = 0;
+ wbt_disable_default(q);
}
/*
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 570021a0dc1c..04325b81c2b4 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -685,7 +685,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
case BLKALIGNOFF:
return compat_put_int(arg, bdev_alignment_offset(bdev));
case BLKDISCARDZEROES:
- return compat_put_uint(arg, bdev_discard_zeroes_data(bdev));
+ return compat_put_uint(arg, 0);
case BLKFLSBUF:
case BLKROSET:
case BLKDISCARD:
diff --git a/block/elevator.c b/block/elevator.c
index 01139f549b5b..bf11e70f008b 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -41,6 +41,7 @@
#include "blk.h"
#include "blk-mq-sched.h"
+#include "blk-wbt.h"
static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);
@@ -242,26 +243,21 @@ int elevator_init(struct request_queue *q, char *name)
}
}
- if (e->uses_mq) {
- err = blk_mq_sched_setup(q);
- if (!err)
- err = e->ops.mq.init_sched(q, e);
- } else
+ if (e->uses_mq)
+ err = blk_mq_init_sched(q, e);
+ else
err = e->ops.sq.elevator_init_fn(q, e);
- if (err) {
- if (e->uses_mq)
- blk_mq_sched_teardown(q);
+ if (err)
elevator_put(e);
- }
return err;
}
EXPORT_SYMBOL(elevator_init);
-void elevator_exit(struct elevator_queue *e)
+void elevator_exit(struct request_queue *q, struct elevator_queue *e)
{
mutex_lock(&e->sysfs_lock);
if (e->uses_mq && e->type->ops.mq.exit_sched)
- e->type->ops.mq.exit_sched(e);
+ blk_mq_exit_sched(q, e);
else if (!e->uses_mq && e->type->ops.sq.elevator_exit_fn)
e->type->ops.sq.elevator_exit_fn(e);
mutex_unlock(&e->sysfs_lock);
@@ -882,6 +878,8 @@ void elv_unregister_queue(struct request_queue *q)
kobject_uevent(&e->kobj, KOBJ_REMOVE);
kobject_del(&e->kobj);
e->registered = 0;
+ /* Re-enable throttling in case elevator disabled it */
+ wbt_enable_default(q);
}
}
EXPORT_SYMBOL(elv_unregister_queue);
@@ -946,6 +944,45 @@ void elv_unregister(struct elevator_type *e)
}
EXPORT_SYMBOL_GPL(elv_unregister);
+static int elevator_switch_mq(struct request_queue *q,
+ struct elevator_type *new_e)
+{
+ int ret;
+
+ blk_mq_freeze_queue(q);
+ blk_mq_quiesce_queue(q);
+
+ if (q->elevator) {
+ if (q->elevator->registered)
+ elv_unregister_queue(q);
+ ioc_clear_queue(q);
+ elevator_exit(q, q->elevator);
+ }
+
+ ret = blk_mq_init_sched(q, new_e);
+ if (ret)
+ goto out;
+
+ if (new_e) {
+ ret = elv_register_queue(q);
+ if (ret) {
+ elevator_exit(q, q->elevator);
+ goto out;
+ }
+ }
+
+ if (new_e)
+ blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
+ else
+ blk_add_trace_msg(q, "elv switch: none");
+
+out:
+ blk_mq_unfreeze_queue(q);
+ blk_mq_start_stopped_hw_queues(q, true);
+ return ret;
+
+}
+
/*
* switch to new_e io scheduler. be careful not to introduce deadlocks -
* we don't free the old io scheduler, before we have allocated what we
@@ -958,10 +995,8 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
bool old_registered = false;
int err;
- if (q->mq_ops) {
- blk_mq_freeze_queue(q);
- blk_mq_quiesce_queue(q);
- }
+ if (q->mq_ops)
+ return elevator_switch_mq(q, new_e);
/*
* Turn on BYPASS and drain all requests w/ elevator private data.
@@ -973,11 +1008,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
if (old) {
old_registered = old->registered;
- if (old->uses_mq)
- blk_mq_sched_teardown(q);
-
- if (!q->mq_ops)
- blk_queue_bypass_start(q);
+ blk_queue_bypass_start(q);
/* unregister and clear all auxiliary data of the old elevator */
if (old_registered)
@@ -987,56 +1018,32 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
}
/* allocate, init and register new elevator */
- if (new_e) {
- if (new_e->uses_mq) {
- err = blk_mq_sched_setup(q);
- if (!err)
- err = new_e->ops.mq.init_sched(q, new_e);
- } else
- err = new_e->ops.sq.elevator_init_fn(q, new_e);
- if (err)
- goto fail_init;
+ err = new_e->ops.sq.elevator_init_fn(q, new_e);
+ if (err)
+ goto fail_init;
- err = elv_register_queue(q);
- if (err)
- goto fail_register;
- } else
- q->elevator = NULL;
+ err = elv_register_queue(q);
+ if (err)
+ goto fail_register;
/* done, kill the old one and finish */
if (old) {
- elevator_exit(old);
- if (!q->mq_ops)
- blk_queue_bypass_end(q);
+ elevator_exit(q, old);
+ blk_queue_bypass_end(q);
}
- if (q->mq_ops) {
- blk_mq_unfreeze_queue(q);
- blk_mq_start_stopped_hw_queues(q, true);
- }
-
- if (new_e)
- blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
- else
- blk_add_trace_msg(q, "elv switch: none");
+ blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
return 0;
fail_register:
- if (q->mq_ops)
- blk_mq_sched_teardown(q);
- elevator_exit(q->elevator);
+ elevator_exit(q, q->elevator);
fail_init:
/* switch failed, restore and re-register old elevator */
if (old) {
q->elevator = old;
elv_register_queue(q);
- if (!q->mq_ops)
- blk_queue_bypass_end(q);
- }
- if (q->mq_ops) {
- blk_mq_unfreeze_queue(q);
- blk_mq_start_stopped_hw_queues(q, true);
+ blk_queue_bypass_end(q);
}
return err;
@@ -1094,12 +1101,20 @@ int elevator_change(struct request_queue *q, const char *name)
}
EXPORT_SYMBOL(elevator_change);
+static inline bool elv_support_iosched(struct request_queue *q)
+{
+ if (q->mq_ops && q->tag_set && (q->tag_set->flags &
+ BLK_MQ_F_NO_SCHED))
+ return false;
+ return true;
+}
+
ssize_t elv_iosched_store(struct request_queue *q, const char *name,
size_t count)
{
int ret;
- if (!(q->mq_ops || q->request_fn))
+ if (!(q->mq_ops || q->request_fn) || !elv_support_iosched(q))
return count;
ret = __elevator_change(q, name);
@@ -1131,7 +1146,7 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
len += sprintf(name+len, "[%s] ", elv->elevator_name);
continue;
}
- if (__e->uses_mq && q->mq_ops)
+ if (__e->uses_mq && q->mq_ops && elv_support_iosched(q))
len += sprintf(name+len, "%s ", __e->elevator_name);
else if (!__e->uses_mq && !q->mq_ops)
len += sprintf(name+len, "%s ", __e->elevator_name);
diff --git a/block/genhd.c b/block/genhd.c
index a9c516a8b37d..d252d29fe837 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -271,16 +271,17 @@ void blkdev_show(struct seq_file *seqf, off_t offset)
/**
* register_blkdev - register a new block device
*
- * @major: the requested major device number [1..255]. If @major=0, try to
+ * @major: the requested major device number [1..255]. If @major = 0, try to
* allocate any unused major number.
* @name: the name of the new block device as a zero terminated string
*
* The @name must be unique within the system.
*
- * The return value depends on the @major input parameter.
+ * The return value depends on the @major input parameter:
+ *
* - if a major device number was requested in range [1..255] then the
* function returns zero on success, or a negative error code
- * - if any unused major number was requested with @major=0 parameter
+ * - if any unused major number was requested with @major = 0 parameter
* then the return value is the allocated major number in range
* [1..255] or a negative error code otherwise
*/
@@ -1060,8 +1061,19 @@ static struct attribute *disk_attrs[] = {
NULL
};
+static umode_t disk_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+ struct device *dev = container_of(kobj, typeof(*dev), kobj);
+ struct gendisk *disk = dev_to_disk(dev);
+
+ if (a == &dev_attr_badblocks.attr && !disk->bb)
+ return 0;
+ return a->mode;
+}
+
static struct attribute_group disk_attr_group = {
.attrs = disk_attrs,
+ .is_visible = disk_visible,
};
static const struct attribute_group *disk_attr_groups[] = {
@@ -1352,7 +1364,7 @@ struct kobject *get_disk(struct gendisk *disk)
owner = disk->fops->owner;
if (owner && !try_module_get(owner))
return NULL;
- kobj = kobject_get(&disk_to_dev(disk)->kobj);
+ kobj = kobject_get_unless_zero(&disk_to_dev(disk)->kobj);
if (kobj == NULL) {
module_put(owner);
return NULL;
diff --git a/block/ioctl.c b/block/ioctl.c
index 7b88820b93d9..0de02ee67eed 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -255,7 +255,7 @@ static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
truncate_inode_pages_range(mapping, start, end);
return blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
- false);
+ BLKDEV_ZERO_NOUNMAP);
}
static int put_ushort(unsigned long arg, unsigned short val)
@@ -547,7 +547,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
case BLKALIGNOFF:
return put_int(arg, bdev_alignment_offset(bdev));
case BLKDISCARDZEROES:
- return put_uint(arg, bdev_discard_zeroes_data(bdev));
+ return put_uint(arg, 0);
case BLKSECTGET:
max_sectors = min_t(unsigned int, USHRT_MAX,
queue_max_sectors(bdev_get_queue(bdev)));
diff --git a/block/ioprio.c b/block/ioprio.c
index 0c47a00f92a8..4b120c9cf7e8 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -163,22 +163,12 @@ out:
int ioprio_best(unsigned short aprio, unsigned short bprio)
{
- unsigned short aclass;
- unsigned short bclass;
-
if (!ioprio_valid(aprio))
aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
if (!ioprio_valid(bprio))
bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
- aclass = IOPRIO_PRIO_CLASS(aprio);
- bclass = IOPRIO_PRIO_CLASS(bprio);
- if (aclass == bclass)
- return min(aprio, bprio);
- if (aclass > bclass)
- return bprio;
- else
- return aprio;
+ return min(aprio, bprio);
}
SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
new file mode 100644
index 000000000000..3b0090bc5dd1
--- /dev/null
+++ b/block/kyber-iosched.c
@@ -0,0 +1,719 @@
+/*
+ * The Kyber I/O scheduler. Controls latency by throttling queue depths using
+ * scalable techniques.
+ *
+ * Copyright (C) 2017 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
+#include <linux/elevator.h>
+#include <linux/module.h>
+#include <linux/sbitmap.h>
+
+#include "blk.h"
+#include "blk-mq.h"
+#include "blk-mq-sched.h"
+#include "blk-mq-tag.h"
+#include "blk-stat.h"
+
+/* Scheduling domains. */
+enum {
+ KYBER_READ,
+ KYBER_SYNC_WRITE,
+ KYBER_OTHER, /* Async writes, discard, etc. */
+ KYBER_NUM_DOMAINS,
+};
+
+enum {
+ KYBER_MIN_DEPTH = 256,
+
+ /*
+ * In order to prevent starvation of synchronous requests by a flood of
+ * asynchronous requests, we reserve 25% of requests for synchronous
+ * operations.
+ */
+ KYBER_ASYNC_PERCENT = 75,
+};
+
+/*
+ * Initial device-wide depths for each scheduling domain.
+ *
+ * Even for fast devices with lots of tags like NVMe, you can saturate
+ * the device with only a fraction of the maximum possible queue depth.
+ * So, we cap these to a reasonable value.
+ */
+static const unsigned int kyber_depth[] = {
+ [KYBER_READ] = 256,
+ [KYBER_SYNC_WRITE] = 128,
+ [KYBER_OTHER] = 64,
+};
+
+/*
+ * Scheduling domain batch sizes. We favor reads.
+ */
+static const unsigned int kyber_batch_size[] = {
+ [KYBER_READ] = 16,
+ [KYBER_SYNC_WRITE] = 8,
+ [KYBER_OTHER] = 8,
+};
+
+struct kyber_queue_data {
+ struct request_queue *q;
+
+ struct blk_stat_callback *cb;
+
+ /*
+ * The device is divided into multiple scheduling domains based on the
+ * request type. Each domain has a fixed number of in-flight requests of
+ * that type device-wide, limited by these tokens.
+ */
+ struct sbitmap_queue domain_tokens[KYBER_NUM_DOMAINS];
+
+ /*
+ * Async request percentage, converted to per-word depth for
+ * sbitmap_get_shallow().
+ */
+ unsigned int async_depth;
+
+ /* Target latencies in nanoseconds. */
+ u64 read_lat_nsec, write_lat_nsec;
+};
+
+struct kyber_hctx_data {
+ spinlock_t lock;
+ struct list_head rqs[KYBER_NUM_DOMAINS];
+ unsigned int cur_domain;
+ unsigned int batching;
+ wait_queue_t domain_wait[KYBER_NUM_DOMAINS];
+ atomic_t wait_index[KYBER_NUM_DOMAINS];
+};
+
+static int rq_sched_domain(const struct request *rq)
+{
+ unsigned int op = rq->cmd_flags;
+
+ if ((op & REQ_OP_MASK) == REQ_OP_READ)
+ return KYBER_READ;
+ else if ((op & REQ_OP_MASK) == REQ_OP_WRITE && op_is_sync(op))
+ return KYBER_SYNC_WRITE;
+ else
+ return KYBER_OTHER;
+}
+
+enum {
+ NONE = 0,
+ GOOD = 1,
+ GREAT = 2,
+ BAD = -1,
+ AWFUL = -2,
+};
+
+#define IS_GOOD(status) ((status) > 0)
+#define IS_BAD(status) ((status) < 0)
+
+static int kyber_lat_status(struct blk_stat_callback *cb,
+ unsigned int sched_domain, u64 target)
+{
+ u64 latency;
+
+ if (!cb->stat[sched_domain].nr_samples)
+ return NONE;
+
+ latency = cb->stat[sched_domain].mean;
+ if (latency >= 2 * target)
+ return AWFUL;
+ else if (latency > target)
+ return BAD;
+ else if (latency <= target / 2)
+ return GREAT;
+ else /* (latency <= target) */
+ return GOOD;
+}
+
+/*
+ * Adjust the read or synchronous write depth given the status of reads and
+ * writes. The goal is that the latencies of the two domains are fair (i.e., if
+ * one is good, then the other is good).
+ */
+static void kyber_adjust_rw_depth(struct kyber_queue_data *kqd,
+ unsigned int sched_domain, int this_status,
+ int other_status)
+{
+ unsigned int orig_depth, depth;
+
+ /*
+ * If this domain had no samples, or reads and writes are both good or
+ * both bad, don't adjust the depth.
+ */
+ if (this_status == NONE ||
+ (IS_GOOD(this_status) && IS_GOOD(other_status)) ||
+ (IS_BAD(this_status) && IS_BAD(other_status)))
+ return;
+
+ orig_depth = depth = kqd->domain_tokens[sched_domain].sb.depth;
+
+ if (other_status == NONE) {
+ depth++;
+ } else {
+ switch (this_status) {
+ case GOOD:
+ if (other_status == AWFUL)
+ depth -= max(depth / 4, 1U);
+ else
+ depth -= max(depth / 8, 1U);
+ break;
+ case GREAT:
+ if (other_status == AWFUL)
+ depth /= 2;
+ else
+ depth -= max(depth / 4, 1U);
+ break;
+ case BAD:
+ depth++;
+ break;
+ case AWFUL:
+ if (other_status == GREAT)
+ depth += 2;
+ else
+ depth++;
+ break;
+ }
+ }
+
+ depth = clamp(depth, 1U, kyber_depth[sched_domain]);
+ if (depth != orig_depth)
+ sbitmap_queue_resize(&kqd->domain_tokens[sched_domain], depth);
+}
+
+/*
+ * Adjust the depth of other requests given the status of reads and synchronous
+ * writes. As long as either domain is doing fine, we don't throttle, but if
+ * both domains are doing badly, we throttle heavily.
+ */
+static void kyber_adjust_other_depth(struct kyber_queue_data *kqd,
+ int read_status, int write_status,
+ bool have_samples)
+{
+ unsigned int orig_depth, depth;
+ int status;
+
+ orig_depth = depth = kqd->domain_tokens[KYBER_OTHER].sb.depth;
+
+ if (read_status == NONE && write_status == NONE) {
+ depth += 2;
+ } else if (have_samples) {
+ if (read_status == NONE)
+ status = write_status;
+ else if (write_status == NONE)
+ status = read_status;
+ else
+ status = max(read_status, write_status);
+ switch (status) {
+ case GREAT:
+ depth += 2;
+ break;
+ case GOOD:
+ depth++;
+ break;
+ case BAD:
+ depth -= max(depth / 4, 1U);
+ break;
+ case AWFUL:
+ depth /= 2;
+ break;
+ }
+ }
+
+ depth = clamp(depth, 1U, kyber_depth[KYBER_OTHER]);
+ if (depth != orig_depth)
+ sbitmap_queue_resize(&kqd->domain_tokens[KYBER_OTHER], depth);
+}
+
+/*
+ * Apply heuristics for limiting queue depths based on gathered latency
+ * statistics.
+ */
+static void kyber_stat_timer_fn(struct blk_stat_callback *cb)
+{
+ struct kyber_queue_data *kqd = cb->data;
+ int read_status, write_status;
+
+ read_status = kyber_lat_status(cb, KYBER_READ, kqd->read_lat_nsec);
+ write_status = kyber_lat_status(cb, KYBER_SYNC_WRITE, kqd->write_lat_nsec);
+
+ kyber_adjust_rw_depth(kqd, KYBER_READ, read_status, write_status);
+ kyber_adjust_rw_depth(kqd, KYBER_SYNC_WRITE, write_status, read_status);
+ kyber_adjust_other_depth(kqd, read_status, write_status,
+ cb->stat[KYBER_OTHER].nr_samples != 0);
+
+ /*
+ * Continue monitoring latencies if we aren't hitting the targets or
+ * we're still throttling other requests.
+ */
+ if (!blk_stat_is_active(kqd->cb) &&
+ ((IS_BAD(read_status) || IS_BAD(write_status) ||
+ kqd->domain_tokens[KYBER_OTHER].sb.depth < kyber_depth[KYBER_OTHER])))
+ blk_stat_activate_msecs(kqd->cb, 100);
+}
+
+static unsigned int kyber_sched_tags_shift(struct kyber_queue_data *kqd)
+{
+ /*
+ * All of the hardware queues have the same depth, so we can just grab
+ * the shift of the first one.
+ */
+ return kqd->q->queue_hw_ctx[0]->sched_tags->bitmap_tags.sb.shift;
+}
+
+static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q)
+{
+ struct kyber_queue_data *kqd;
+ unsigned int max_tokens;
+ unsigned int shift;
+ int ret = -ENOMEM;
+ int i;
+
+ kqd = kmalloc_node(sizeof(*kqd), GFP_KERNEL, q->node);
+ if (!kqd)
+ goto err;
+ kqd->q = q;
+
+ kqd->cb = blk_stat_alloc_callback(kyber_stat_timer_fn, rq_sched_domain,
+ KYBER_NUM_DOMAINS, kqd);
+ if (!kqd->cb)
+ goto err_kqd;
+
+ /*
+ * The maximum number of tokens for any scheduling domain is at least
+ * the queue depth of a single hardware queue. If the hardware doesn't
+ * have many tags, still provide a reasonable number.
+ */
+ max_tokens = max_t(unsigned int, q->tag_set->queue_depth,
+ KYBER_MIN_DEPTH);
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
+ WARN_ON(!kyber_depth[i]);
+ WARN_ON(!kyber_batch_size[i]);
+ ret = sbitmap_queue_init_node(&kqd->domain_tokens[i],
+ max_tokens, -1, false, GFP_KERNEL,
+ q->node);
+ if (ret) {
+ while (--i >= 0)
+ sbitmap_queue_free(&kqd->domain_tokens[i]);
+ goto err_cb;
+ }
+ sbitmap_queue_resize(&kqd->domain_tokens[i], kyber_depth[i]);
+ }
+
+ shift = kyber_sched_tags_shift(kqd);
+ kqd->async_depth = (1U << shift) * KYBER_ASYNC_PERCENT / 100U;
+
+ kqd->read_lat_nsec = 2000000ULL;
+ kqd->write_lat_nsec = 10000000ULL;
+
+ return kqd;
+
+err_cb:
+ blk_stat_free_callback(kqd->cb);
+err_kqd:
+ kfree(kqd);
+err:
+ return ERR_PTR(ret);
+}
+
+static int kyber_init_sched(struct request_queue *q, struct elevator_type *e)
+{
+ struct kyber_queue_data *kqd;
+ struct elevator_queue *eq;
+
+ eq = elevator_alloc(q, e);
+ if (!eq)
+ return -ENOMEM;
+
+ kqd = kyber_queue_data_alloc(q);
+ if (IS_ERR(kqd)) {
+ kobject_put(&eq->kobj);
+ return PTR_ERR(kqd);
+ }
+
+ eq->elevator_data = kqd;
+ q->elevator = eq;
+
+ blk_stat_add_callback(q, kqd->cb);
+
+ return 0;
+}
+
+static void kyber_exit_sched(struct elevator_queue *e)
+{
+ struct kyber_queue_data *kqd = e->elevator_data;
+ struct request_queue *q = kqd->q;
+ int i;
+
+ blk_stat_remove_callback(q, kqd->cb);
+
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++)
+ sbitmap_queue_free(&kqd->domain_tokens[i]);
+ blk_stat_free_callback(kqd->cb);
+ kfree(kqd);
+}
+
+static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
+{
+ struct kyber_hctx_data *khd;
+ int i;
+
+ khd = kmalloc_node(sizeof(*khd), GFP_KERNEL, hctx->numa_node);
+ if (!khd)
+ return -ENOMEM;
+
+ spin_lock_init(&khd->lock);
+
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
+ INIT_LIST_HEAD(&khd->rqs[i]);
+ INIT_LIST_HEAD(&khd->domain_wait[i].task_list);
+ atomic_set(&khd->wait_index[i], 0);
+ }
+
+ khd->cur_domain = 0;
+ khd->batching = 0;
+
+ hctx->sched_data = khd;
+
+ return 0;
+}
+
+static void kyber_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
+{
+ kfree(hctx->sched_data);
+}
+
+static int rq_get_domain_token(struct request *rq)
+{
+ return (long)rq->elv.priv[0];
+}
+
+static void rq_set_domain_token(struct request *rq, int token)
+{
+ rq->elv.priv[0] = (void *)(long)token;
+}
+
+static void rq_clear_domain_token(struct kyber_queue_data *kqd,
+ struct request *rq)
+{
+ unsigned int sched_domain;
+ int nr;
+
+ nr = rq_get_domain_token(rq);
+ if (nr != -1) {
+ sched_domain = rq_sched_domain(rq);
+ sbitmap_queue_clear(&kqd->domain_tokens[sched_domain], nr,
+ rq->mq_ctx->cpu);
+ }
+}
+
+static struct request *kyber_get_request(struct request_queue *q,
+ unsigned int op,
+ struct blk_mq_alloc_data *data)
+{
+ struct kyber_queue_data *kqd = q->elevator->elevator_data;
+ struct request *rq;
+
+ /*
+ * We use the scheduler tags as per-hardware queue queueing tokens.
+ * Async requests can be limited at this stage.
+ */
+ if (!op_is_sync(op))
+ data->shallow_depth = kqd->async_depth;
+
+ rq = __blk_mq_alloc_request(data, op);
+ if (rq)
+ rq_set_domain_token(rq, -1);
+ return rq;
+}
+
+static void kyber_put_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ struct kyber_queue_data *kqd = q->elevator->elevator_data;
+
+ rq_clear_domain_token(kqd, rq);
+ blk_mq_finish_request(rq);
+}
+
+static void kyber_completed_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ struct kyber_queue_data *kqd = q->elevator->elevator_data;
+ unsigned int sched_domain;
+ u64 now, latency, target;
+
+ /*
+ * Check if this request met our latency goal. If not, quickly gather
+ * some statistics and start throttling.
+ */
+ sched_domain = rq_sched_domain(rq);
+ switch (sched_domain) {
+ case KYBER_READ:
+ target = kqd->read_lat_nsec;
+ break;
+ case KYBER_SYNC_WRITE:
+ target = kqd->write_lat_nsec;
+ break;
+ default:
+ return;
+ }
+
+ /* If we are already monitoring latencies, don't check again. */
+ if (blk_stat_is_active(kqd->cb))
+ return;
+
+ now = __blk_stat_time(ktime_to_ns(ktime_get()));
+ if (now < blk_stat_time(&rq->issue_stat))
+ return;
+
+ latency = now - blk_stat_time(&rq->issue_stat);
+
+ if (latency > target)
+ blk_stat_activate_msecs(kqd->cb, 10);
+}
+
+static void kyber_flush_busy_ctxs(struct kyber_hctx_data *khd,
+ struct blk_mq_hw_ctx *hctx)
+{
+ LIST_HEAD(rq_list);
+ struct request *rq, *next;
+
+ blk_mq_flush_busy_ctxs(hctx, &rq_list);
+ list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
+ unsigned int sched_domain;
+
+ sched_domain = rq_sched_domain(rq);
+ list_move_tail(&rq->queuelist, &khd->rqs[sched_domain]);
+ }
+}
+
+static int kyber_domain_wake(wait_queue_t *wait, unsigned mode, int flags,
+ void *key)
+{
+ struct blk_mq_hw_ctx *hctx = READ_ONCE(wait->private);
+
+ list_del_init(&wait->task_list);
+ blk_mq_run_hw_queue(hctx, true);
+ return 1;
+}
+
+static int kyber_get_domain_token(struct kyber_queue_data *kqd,
+ struct kyber_hctx_data *khd,
+ struct blk_mq_hw_ctx *hctx)
+{
+ unsigned int sched_domain = khd->cur_domain;
+ struct sbitmap_queue *domain_tokens = &kqd->domain_tokens[sched_domain];
+ wait_queue_t *wait = &khd->domain_wait[sched_domain];
+ struct sbq_wait_state *ws;
+ int nr;
+
+ nr = __sbitmap_queue_get(domain_tokens);
+ if (nr >= 0)
+ return nr;
+
+ /*
+ * If we failed to get a domain token, make sure the hardware queue is
+ * run when one becomes available. Note that this is serialized on
+ * khd->lock, but we still need to be careful about the waker.
+ */
+ if (list_empty_careful(&wait->task_list)) {
+ init_waitqueue_func_entry(wait, kyber_domain_wake);
+ wait->private = hctx;
+ ws = sbq_wait_ptr(domain_tokens,
+ &khd->wait_index[sched_domain]);
+ add_wait_queue(&ws->wait, wait);
+
+ /*
+ * Try again in case a token was freed before we got on the wait
+ * queue.
+ */
+ nr = __sbitmap_queue_get(domain_tokens);
+ }
+ return nr;
+}
+
+static struct request *
+kyber_dispatch_cur_domain(struct kyber_queue_data *kqd,
+ struct kyber_hctx_data *khd,
+ struct blk_mq_hw_ctx *hctx,
+ bool *flushed)
+{
+ struct list_head *rqs;
+ struct request *rq;
+ int nr;
+
+ rqs = &khd->rqs[khd->cur_domain];
+ rq = list_first_entry_or_null(rqs, struct request, queuelist);
+
+ /*
+ * If there wasn't already a pending request and we haven't flushed the
+ * software queues yet, flush the software queues and check again.
+ */
+ if (!rq && !*flushed) {
+ kyber_flush_busy_ctxs(khd, hctx);
+ *flushed = true;
+ rq = list_first_entry_or_null(rqs, struct request, queuelist);
+ }
+
+ if (rq) {
+ nr = kyber_get_domain_token(kqd, khd, hctx);
+ if (nr >= 0) {
+ khd->batching++;
+ rq_set_domain_token(rq, nr);
+ list_del_init(&rq->queuelist);
+ return rq;
+ }
+ }
+
+ /* There were either no pending requests or no tokens. */
+ return NULL;
+}
+
+static struct request *kyber_dispatch_request(struct blk_mq_hw_ctx *hctx)
+{
+ struct kyber_queue_data *kqd = hctx->queue->elevator->elevator_data;
+ struct kyber_hctx_data *khd = hctx->sched_data;
+ bool flushed = false;
+ struct request *rq;
+ int i;
+
+ spin_lock(&khd->lock);
+
+ /*
+ * First, if we are still entitled to batch, try to dispatch a request
+ * from the batch.
+ */
+ if (khd->batching < kyber_batch_size[khd->cur_domain]) {
+ rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
+ if (rq)
+ goto out;
+ }
+
+ /*
+ * Either,
+ * 1. We were no longer entitled to a batch.
+ * 2. The domain we were batching didn't have any requests.
+ * 3. The domain we were batching was out of tokens.
+ *
+ * Start another batch. Note that this wraps back around to the original
+ * domain if no other domains have requests or tokens.
+ */
+ khd->batching = 0;
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
+ if (khd->cur_domain == KYBER_NUM_DOMAINS - 1)
+ khd->cur_domain = 0;
+ else
+ khd->cur_domain++;
+
+ rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
+ if (rq)
+ goto out;
+ }
+
+ rq = NULL;
+out:
+ spin_unlock(&khd->lock);
+ return rq;
+}
+
+static bool kyber_has_work(struct blk_mq_hw_ctx *hctx)
+{
+ struct kyber_hctx_data *khd = hctx->sched_data;
+ int i;
+
+ for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
+ if (!list_empty_careful(&khd->rqs[i]))
+ return true;
+ }
+ return false;
+}
+
+#define KYBER_LAT_SHOW_STORE(op) \
+static ssize_t kyber_##op##_lat_show(struct elevator_queue *e, \
+ char *page) \
+{ \
+ struct kyber_queue_data *kqd = e->elevator_data; \
+ \
+ return sprintf(page, "%llu\n", kqd->op##_lat_nsec); \
+} \
+ \
+static ssize_t kyber_##op##_lat_store(struct elevator_queue *e, \
+ const char *page, size_t count) \
+{ \
+ struct kyber_queue_data *kqd = e->elevator_data; \
+ unsigned long long nsec; \
+ int ret; \
+ \
+ ret = kstrtoull(page, 10, &nsec); \
+ if (ret) \
+ return ret; \
+ \
+ kqd->op##_lat_nsec = nsec; \
+ \
+ return count; \
+}
+KYBER_LAT_SHOW_STORE(read);
+KYBER_LAT_SHOW_STORE(write);
+#undef KYBER_LAT_SHOW_STORE
+
+#define KYBER_LAT_ATTR(op) __ATTR(op##_lat_nsec, 0644, kyber_##op##_lat_show, kyber_##op##_lat_store)
+static struct elv_fs_entry kyber_sched_attrs[] = {
+ KYBER_LAT_ATTR(read),
+ KYBER_LAT_ATTR(write),
+ __ATTR_NULL
+};
+#undef KYBER_LAT_ATTR
+
+static struct elevator_type kyber_sched = {
+ .ops.mq = {
+ .init_sched = kyber_init_sched,
+ .exit_sched = kyber_exit_sched,
+ .init_hctx = kyber_init_hctx,
+ .exit_hctx = kyber_exit_hctx,
+ .get_request = kyber_get_request,
+ .put_request = kyber_put_request,
+ .completed_request = kyber_completed_request,
+ .dispatch_request = kyber_dispatch_request,
+ .has_work = kyber_has_work,
+ },
+ .uses_mq = true,
+ .elevator_attrs = kyber_sched_attrs,
+ .elevator_name = "kyber",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init kyber_init(void)
+{
+ return elv_register(&kyber_sched);
+}
+
+static void __exit kyber_exit(void)
+{
+ elv_unregister(&kyber_sched);
+}
+
+module_init(kyber_init);
+module_exit(kyber_exit);
+
+MODULE_AUTHOR("Omar Sandoval");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Kyber I/O scheduler");
diff --git a/block/partition-generic.c b/block/partition-generic.c
index 5dfac337b0f2..ff07b9143ca4 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -496,7 +496,6 @@ rescan:
if (disk->fops->revalidate_disk)
disk->fops->revalidate_disk(disk);
- blk_integrity_revalidate(disk);
check_disk_size_change(disk, bdev);
bdev->bd_invalidated = 0;
if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 2a2fc768b27a..4a294a5f7fab 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -262,11 +262,11 @@ static int blk_complete_sghdr_rq(struct request *rq, struct sg_io_hdr *hdr,
/*
* fill in all the output members
*/
- hdr->status = rq->errors & 0xff;
- hdr->masked_status = status_byte(rq->errors);
- hdr->msg_status = msg_byte(rq->errors);
- hdr->host_status = host_byte(rq->errors);
- hdr->driver_status = driver_byte(rq->errors);
+ hdr->status = req->result & 0xff;
+ hdr->masked_status = status_byte(req->result);
+ hdr->msg_status = msg_byte(req->result);
+ hdr->host_status = host_byte(req->result);
+ hdr->driver_status = driver_byte(req->result);
hdr->info = 0;
if (hdr->masked_status || hdr->host_status || hdr->driver_status)
hdr->info |= SG_INFO_CHECK;
@@ -362,7 +362,7 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
goto out_free_cdb;
bio = rq->bio;
- rq->retries = 0;
+ req->retries = 0;
start_time = jiffies;
@@ -476,13 +476,13 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
goto error;
/* default. possible overriden later */
- rq->retries = 5;
+ req->retries = 5;
switch (opcode) {
case SEND_DIAGNOSTIC:
case FORMAT_UNIT:
rq->timeout = FORMAT_UNIT_TIMEOUT;
- rq->retries = 1;
+ req->retries = 1;
break;
case START_STOP:
rq->timeout = START_STOP_TIMEOUT;
@@ -495,7 +495,7 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
break;
case READ_DEFECT_DATA:
rq->timeout = READ_DEFECT_DATA_TIMEOUT;
- rq->retries = 1;
+ req->retries = 1;
break;
default:
rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
@@ -509,7 +509,7 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
blk_execute_rq(q, disk, rq, 0);
- err = rq->errors & 0xff; /* only 8 bit SCSI status */
+ err = req->result & 0xff; /* only 8 bit SCSI status */
if (err) {
if (req->sense_len && req->sense) {
bytes = (OMAX_SB_LEN > req->sense_len) ?
@@ -547,7 +547,8 @@ static int __blk_send_generic(struct request_queue *q, struct gendisk *bd_disk,
scsi_req(rq)->cmd[0] = cmd;
scsi_req(rq)->cmd[4] = data;
scsi_req(rq)->cmd_len = 6;
- err = blk_execute_rq(q, bd_disk, rq, 0);
+ blk_execute_rq(q, bd_disk, rq, 0);
+ err = scsi_req(rq)->result ? -EIO : 0;
blk_put_request(rq);
return err;
diff --git a/block/sed-opal.c b/block/sed-opal.c
index 14035f826b5e..9b30ae5ab843 100644
--- a/block/sed-opal.c
+++ b/block/sed-opal.c
@@ -275,8 +275,8 @@ static bool check_tper(const void *data)
u8 flags = tper->supported_features;
if (!(flags & TPER_SYNC_SUPPORTED)) {
- pr_err("TPer sync not supported. flags = %d\n",
- tper->supported_features);
+ pr_debug("TPer sync not supported. flags = %d\n",
+ tper->supported_features);
return false;
}
@@ -289,7 +289,7 @@ static bool check_sum(const void *data)
u32 nlo = be32_to_cpu(sum->num_locking_objects);
if (nlo == 0) {
- pr_err("Need at least one locking object.\n");
+ pr_debug("Need at least one locking object.\n");
return false;
}
@@ -385,9 +385,9 @@ static int next(struct opal_dev *dev)
error = step->fn(dev, step->data);
if (error) {
- pr_err("Error on step function: %d with error %d: %s\n",
- state, error,
- opal_error_to_human(error));
+ pr_debug("Error on step function: %d with error %d: %s\n",
+ state, error,
+ opal_error_to_human(error));
/* For each OPAL command we do a discovery0 then we
* start some sort of session.
@@ -419,8 +419,8 @@ static int opal_discovery0_end(struct opal_dev *dev)
print_buffer(dev->resp, hlen);
if (hlen > IO_BUFFER_LENGTH - sizeof(*hdr)) {
- pr_warn("Discovery length overflows buffer (%zu+%u)/%u\n",
- sizeof(*hdr), hlen, IO_BUFFER_LENGTH);
+ pr_debug("Discovery length overflows buffer (%zu+%u)/%u\n",
+ sizeof(*hdr), hlen, IO_BUFFER_LENGTH);
return -EFAULT;
}
@@ -503,7 +503,7 @@ static void add_token_u8(int *err, struct opal_dev *cmd, u8 tok)
if (*err)
return;
if (cmd->pos >= IO_BUFFER_LENGTH - 1) {
- pr_err("Error adding u8: end of buffer.\n");
+ pr_debug("Error adding u8: end of buffer.\n");
*err = -ERANGE;
return;
}
@@ -553,7 +553,7 @@ static void add_token_u64(int *err, struct opal_dev *cmd, u64 number)
len = DIV_ROUND_UP(msb, 4);
if (cmd->pos >= IO_BUFFER_LENGTH - len - 1) {
- pr_err("Error adding u64: end of buffer.\n");
+ pr_debug("Error adding u64: end of buffer.\n");
*err = -ERANGE;
return;
}
@@ -579,7 +579,7 @@ static void add_token_bytestring(int *err, struct opal_dev *cmd,
}
if (len >= IO_BUFFER_LENGTH - cmd->pos - header_len) {
- pr_err("Error adding bytestring: end of buffer.\n");
+ pr_debug("Error adding bytestring: end of buffer.\n");
*err = -ERANGE;
return;
}
@@ -597,7 +597,7 @@ static void add_token_bytestring(int *err, struct opal_dev *cmd,
static int build_locking_range(u8 *buffer, size_t length, u8 lr)
{
if (length > OPAL_UID_LENGTH) {
- pr_err("Can't build locking range. Length OOB\n");
+ pr_debug("Can't build locking range. Length OOB\n");
return -ERANGE;
}
@@ -614,7 +614,7 @@ static int build_locking_range(u8 *buffer, size_t length, u8 lr)
static int build_locking_user(u8 *buffer, size_t length, u8 lr)
{
if (length > OPAL_UID_LENGTH) {
- pr_err("Can't build locking range user, Length OOB\n");
+ pr_debug("Can't build locking range user, Length OOB\n");
return -ERANGE;
}
@@ -648,7 +648,7 @@ static int cmd_finalize(struct opal_dev *cmd, u32 hsn, u32 tsn)
add_token_u8(&err, cmd, OPAL_ENDLIST);
if (err) {
- pr_err("Error finalizing command.\n");
+ pr_debug("Error finalizing command.\n");
return -EFAULT;
}
@@ -660,7 +660,7 @@ static int cmd_finalize(struct opal_dev *cmd, u32 hsn, u32 tsn)
hdr->subpkt.length = cpu_to_be32(cmd->pos - sizeof(*hdr));
while (cmd->pos % 4) {
if (cmd->pos >= IO_BUFFER_LENGTH) {
- pr_err("Error: Buffer overrun\n");
+ pr_debug("Error: Buffer overrun\n");
return -ERANGE;
}
cmd->cmd[cmd->pos++] = 0;
@@ -679,14 +679,14 @@ static const struct opal_resp_tok *response_get_token(
const struct opal_resp_tok *tok;
if (n >= resp->num) {
- pr_err("Token number doesn't exist: %d, resp: %d\n",
- n, resp->num);
+ pr_debug("Token number doesn't exist: %d, resp: %d\n",
+ n, resp->num);
return ERR_PTR(-EINVAL);
}
tok = &resp->toks[n];
if (tok->len == 0) {
- pr_err("Token length must be non-zero\n");
+ pr_debug("Token length must be non-zero\n");
return ERR_PTR(-EINVAL);
}
@@ -727,7 +727,7 @@ static ssize_t response_parse_short(struct opal_resp_tok *tok,
tok->type = OPAL_DTA_TOKENID_UINT;
if (tok->len > 9) {
- pr_warn("uint64 with more than 8 bytes\n");
+ pr_debug("uint64 with more than 8 bytes\n");
return -EINVAL;
}
for (i = tok->len - 1; i > 0; i--) {
@@ -814,8 +814,8 @@ static int response_parse(const u8 *buf, size_t length,
if (clen == 0 || plen == 0 || slen == 0 ||
slen > IO_BUFFER_LENGTH - sizeof(*hdr)) {
- pr_err("Bad header length. cp: %u, pkt: %u, subpkt: %u\n",
- clen, plen, slen);
+ pr_debug("Bad header length. cp: %u, pkt: %u, subpkt: %u\n",
+ clen, plen, slen);
print_buffer(pos, sizeof(*hdr));
return -EINVAL;
}
@@ -848,7 +848,7 @@ static int response_parse(const u8 *buf, size_t length,
}
if (num_entries == 0) {
- pr_err("Couldn't parse response.\n");
+ pr_debug("Couldn't parse response.\n");
return -EINVAL;
}
resp->num = num_entries;
@@ -861,18 +861,18 @@ static size_t response_get_string(const struct parsed_resp *resp, int n,
{
*store = NULL;
if (!resp) {
- pr_err("Response is NULL\n");
+ pr_debug("Response is NULL\n");
return 0;
}
if (n > resp->num) {
- pr_err("Response has %d tokens. Can't access %d\n",
- resp->num, n);
+ pr_debug("Response has %d tokens. Can't access %d\n",
+ resp->num, n);
return 0;
}
if (resp->toks[n].type != OPAL_DTA_TOKENID_BYTESTRING) {
- pr_err("Token is not a byte string!\n");
+ pr_debug("Token is not a byte string!\n");
return 0;
}
@@ -883,26 +883,26 @@ static size_t response_get_string(const struct parsed_resp *resp, int n,
static u64 response_get_u64(const struct parsed_resp *resp, int n)
{
if (!resp) {
- pr_err("Response is NULL\n");
+ pr_debug("Response is NULL\n");
return 0;
}
if (n > resp->num) {
- pr_err("Response has %d tokens. Can't access %d\n",
- resp->num, n);
+ pr_debug("Response has %d tokens. Can't access %d\n",
+ resp->num, n);
return 0;
}
if (resp->toks[n].type != OPAL_DTA_TOKENID_UINT) {
- pr_err("Token is not unsigned it: %d\n",
- resp->toks[n].type);
+ pr_debug("Token is not unsigned it: %d\n",
+ resp->toks[n].type);
return 0;
}
if (!(resp->toks[n].width == OPAL_WIDTH_TINY ||
resp->toks[n].width == OPAL_WIDTH_SHORT)) {
- pr_err("Atom is not short or tiny: %d\n",
- resp->toks[n].width);
+ pr_debug("Atom is not short or tiny: %d\n",
+ resp->toks[n].width);
return 0;
}
@@ -949,7 +949,7 @@ static int parse_and_check_status(struct opal_dev *dev)
error = response_parse(dev->resp, IO_BUFFER_LENGTH, &dev->parsed);
if (error) {
- pr_err("Couldn't parse response.\n");
+ pr_debug("Couldn't parse response.\n");
return error;
}
@@ -975,7 +975,7 @@ static int start_opal_session_cont(struct opal_dev *dev)
tsn = response_get_u64(&dev->parsed, 5);
if (hsn == 0 && tsn == 0) {
- pr_err("Couldn't authenticate session\n");
+ pr_debug("Couldn't authenticate session\n");
return -EPERM;
}
@@ -1012,7 +1012,7 @@ static int finalize_and_send(struct opal_dev *dev, cont_fn cont)
ret = cmd_finalize(dev, dev->hsn, dev->tsn);
if (ret) {
- pr_err("Error finalizing command buffer: %d\n", ret);
+ pr_debug("Error finalizing command buffer: %d\n", ret);
return ret;
}
@@ -1041,7 +1041,7 @@ static int gen_key(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building gen key command\n");
+ pr_debug("Error building gen key command\n");
return err;
}
@@ -1059,8 +1059,8 @@ static int get_active_key_cont(struct opal_dev *dev)
return error;
keylen = response_get_string(&dev->parsed, 4, &activekey);
if (!activekey) {
- pr_err("%s: Couldn't extract the Activekey from the response\n",
- __func__);
+ pr_debug("%s: Couldn't extract the Activekey from the response\n",
+ __func__);
return OPAL_INVAL_PARAM;
}
dev->prev_data = kmemdup(activekey, keylen, GFP_KERNEL);
@@ -1103,7 +1103,7 @@ static int get_active_key(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building get active key command\n");
+ pr_debug("Error building get active key command\n");
return err;
}
@@ -1159,7 +1159,7 @@ static inline int enable_global_lr(struct opal_dev *dev, u8 *uid,
err = generic_lr_enable_disable(dev, uid, !!setup->RLE, !!setup->WLE,
0, 0);
if (err)
- pr_err("Failed to create enable global lr command\n");
+ pr_debug("Failed to create enable global lr command\n");
return err;
}
@@ -1217,7 +1217,7 @@ static int setup_locking_range(struct opal_dev *dev, void *data)
}
if (err) {
- pr_err("Error building Setup Locking range command.\n");
+ pr_debug("Error building Setup Locking range command.\n");
return err;
}
@@ -1234,11 +1234,8 @@ static int start_generic_opal_session(struct opal_dev *dev,
u32 hsn;
int err = 0;
- if (key == NULL && auth != OPAL_ANYBODY_UID) {
- pr_err("%s: Attempted to open ADMIN_SP Session without a Host" \
- "Challenge, and not as the Anybody UID\n", __func__);
+ if (key == NULL && auth != OPAL_ANYBODY_UID)
return OPAL_INVAL_PARAM;
- }
clear_opal_cmd(dev);
@@ -1273,12 +1270,12 @@ static int start_generic_opal_session(struct opal_dev *dev,
add_token_u8(&err, dev, OPAL_ENDLIST);
break;
default:
- pr_err("Cannot start Admin SP session with auth %d\n", auth);
+ pr_debug("Cannot start Admin SP session with auth %d\n", auth);
return OPAL_INVAL_PARAM;
}
if (err) {
- pr_err("Error building start adminsp session command.\n");
+ pr_debug("Error building start adminsp session command.\n");
return err;
}
@@ -1369,7 +1366,7 @@ static int start_auth_opal_session(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building STARTSESSION command.\n");
+ pr_debug("Error building STARTSESSION command.\n");
return err;
}
@@ -1391,7 +1388,7 @@ static int revert_tper(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_STARTLIST);
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building REVERT TPER command.\n");
+ pr_debug("Error building REVERT TPER command.\n");
return err;
}
@@ -1426,7 +1423,7 @@ static int internal_activate_user(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building Activate UserN command.\n");
+ pr_debug("Error building Activate UserN command.\n");
return err;
}
@@ -1453,7 +1450,7 @@ static int erase_locking_range(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building Erase Locking Range Command.\n");
+ pr_debug("Error building Erase Locking Range Command.\n");
return err;
}
return finalize_and_send(dev, parse_and_check_status);
@@ -1484,7 +1481,7 @@ static int set_mbr_done(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error Building set MBR Done command\n");
+ pr_debug("Error Building set MBR Done command\n");
return err;
}
@@ -1516,7 +1513,7 @@ static int set_mbr_enable_disable(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error Building set MBR done command\n");
+ pr_debug("Error Building set MBR done command\n");
return err;
}
@@ -1567,7 +1564,7 @@ static int set_new_pw(struct opal_dev *dev, void *data)
if (generic_pw_cmd(usr->opal_key.key, usr->opal_key.key_len,
cpin_uid, dev)) {
- pr_err("Error building set password command.\n");
+ pr_debug("Error building set password command.\n");
return -ERANGE;
}
@@ -1582,7 +1579,7 @@ static int set_sid_cpin_pin(struct opal_dev *dev, void *data)
memcpy(cpin_uid, opaluid[OPAL_C_PIN_SID], OPAL_UID_LENGTH);
if (generic_pw_cmd(key->key, key->key_len, cpin_uid, dev)) {
- pr_err("Error building Set SID cpin\n");
+ pr_debug("Error building Set SID cpin\n");
return -ERANGE;
}
return finalize_and_send(dev, parse_and_check_status);
@@ -1657,7 +1654,7 @@ static int add_user_to_lr(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building add user to locking range command.\n");
+ pr_debug("Error building add user to locking range command.\n");
return err;
}
@@ -1691,7 +1688,7 @@ static int lock_unlock_locking_range(struct opal_dev *dev, void *data)
/* vars are initalized to locked */
break;
default:
- pr_err("Tried to set an invalid locking state... returning to uland\n");
+ pr_debug("Tried to set an invalid locking state... returning to uland\n");
return OPAL_INVAL_PARAM;
}
@@ -1718,7 +1715,7 @@ static int lock_unlock_locking_range(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building SET command.\n");
+ pr_debug("Error building SET command.\n");
return err;
}
return finalize_and_send(dev, parse_and_check_status);
@@ -1752,14 +1749,14 @@ static int lock_unlock_locking_range_sum(struct opal_dev *dev, void *data)
/* vars are initalized to locked */
break;
default:
- pr_err("Tried to set an invalid locking state.\n");
+ pr_debug("Tried to set an invalid locking state.\n");
return OPAL_INVAL_PARAM;
}
ret = generic_lr_enable_disable(dev, lr_buffer, 1, 1,
read_locked, write_locked);
if (ret < 0) {
- pr_err("Error building SET command.\n");
+ pr_debug("Error building SET command.\n");
return ret;
}
return finalize_and_send(dev, parse_and_check_status);
@@ -1811,7 +1808,7 @@ static int activate_lsp(struct opal_dev *dev, void *data)
}
if (err) {
- pr_err("Error building Activate LockingSP command.\n");
+ pr_debug("Error building Activate LockingSP command.\n");
return err;
}
@@ -1831,7 +1828,7 @@ static int get_lsp_lifecycle_cont(struct opal_dev *dev)
/* 0x08 is Manufacured Inactive */
/* 0x09 is Manufactured */
if (lc_status != OPAL_MANUFACTURED_INACTIVE) {
- pr_err("Couldn't determine the status of the Lifcycle state\n");
+ pr_debug("Couldn't determine the status of the Lifecycle state\n");
return -ENODEV;
}
@@ -1868,7 +1865,7 @@ static int get_lsp_lifecycle(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error Building GET Lifecycle Status command\n");
+ pr_debug("Error Building GET Lifecycle Status command\n");
return err;
}
@@ -1887,7 +1884,7 @@ static int get_msid_cpin_pin_cont(struct opal_dev *dev)
strlen = response_get_string(&dev->parsed, 4, &msid_pin);
if (!msid_pin) {
- pr_err("%s: Couldn't extract PIN from response\n", __func__);
+ pr_debug("%s: Couldn't extract PIN from response\n", __func__);
return OPAL_INVAL_PARAM;
}
@@ -1929,7 +1926,7 @@ static int get_msid_cpin_pin(struct opal_dev *dev, void *data)
add_token_u8(&err, dev, OPAL_ENDLIST);
if (err) {
- pr_err("Error building Get MSID CPIN PIN command.\n");
+ pr_debug("Error building Get MSID CPIN PIN command.\n");
return err;
}
@@ -2124,18 +2121,18 @@ static int opal_add_user_to_lr(struct opal_dev *dev,
if (lk_unlk->l_state != OPAL_RO &&
lk_unlk->l_state != OPAL_RW) {
- pr_err("Locking state was not RO or RW\n");
+ pr_debug("Locking state was not RO or RW\n");
return -EINVAL;
}
if (lk_unlk->session.who < OPAL_USER1 ||
lk_unlk->session.who > OPAL_USER9) {
- pr_err("Authority was not within the range of users: %d\n",
- lk_unlk->session.who);
+ pr_debug("Authority was not within the range of users: %d\n",
+ lk_unlk->session.who);
return -EINVAL;
}
if (lk_unlk->session.sum) {
- pr_err("%s not supported in sum. Use setup locking range\n",
- __func__);
+ pr_debug("%s not supported in sum. Use setup locking range\n",
+ __func__);
return -EINVAL;
}
@@ -2312,7 +2309,7 @@ static int opal_activate_user(struct opal_dev *dev,
/* We can't activate Admin1 it's active as manufactured */
if (opal_session->who < OPAL_USER1 ||
opal_session->who > OPAL_USER9) {
- pr_err("Who was not a valid user: %d\n", opal_session->who);
+ pr_debug("Who was not a valid user: %d\n", opal_session->who);
return -EINVAL;
}
@@ -2343,9 +2340,9 @@ bool opal_unlock_from_suspend(struct opal_dev *dev)
ret = __opal_lock_unlock(dev, &suspend->unlk);
if (ret) {
- pr_warn("Failed to unlock LR %hhu with sum %d\n",
- suspend->unlk.session.opal_key.lr,
- suspend->unlk.session.sum);
+ pr_debug("Failed to unlock LR %hhu with sum %d\n",
+ suspend->unlk.session.opal_key.lr,
+ suspend->unlk.session.sum);
was_failure = true;
}
}
@@ -2363,10 +2360,8 @@ int sed_ioctl(struct opal_dev *dev, unsigned int cmd, void __user *arg)
return -EACCES;
if (!dev)
return -ENOTSUPP;
- if (!dev->supported) {
- pr_err("Not supported\n");
+ if (!dev->supported)
return -ENOTSUPP;
- }
p = memdup_user(arg, _IOC_SIZE(cmd));
if (IS_ERR(p))
@@ -2410,7 +2405,7 @@ int sed_ioctl(struct opal_dev *dev, unsigned int cmd, void __user *arg)
ret = opal_secure_erase_locking_range(dev, p);
break;
default:
- pr_warn("No such Opal Ioctl %u\n", cmd);
+ break;
}
kfree(p);
diff --git a/block/t10-pi.c b/block/t10-pi.c
index 2c97912335a9..680c6d636298 100644
--- a/block/t10-pi.c
+++ b/block/t10-pi.c
@@ -160,28 +160,28 @@ static int t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)
return t10_pi_verify(iter, t10_pi_ip_fn, 3);
}
-struct blk_integrity_profile t10_pi_type1_crc = {
+const struct blk_integrity_profile t10_pi_type1_crc = {
.name = "T10-DIF-TYPE1-CRC",
.generate_fn = t10_pi_type1_generate_crc,
.verify_fn = t10_pi_type1_verify_crc,
};
EXPORT_SYMBOL(t10_pi_type1_crc);
-struct blk_integrity_profile t10_pi_type1_ip = {
+const struct blk_integrity_profile t10_pi_type1_ip = {
.name = "T10-DIF-TYPE1-IP",
.generate_fn = t10_pi_type1_generate_ip,
.verify_fn = t10_pi_type1_verify_ip,
};
EXPORT_SYMBOL(t10_pi_type1_ip);
-struct blk_integrity_profile t10_pi_type3_crc = {
+const struct blk_integrity_profile t10_pi_type3_crc = {
.name = "T10-DIF-TYPE3-CRC",
.generate_fn = t10_pi_type3_generate_crc,
.verify_fn = t10_pi_type3_verify_crc,
};
EXPORT_SYMBOL(t10_pi_type3_crc);
-struct blk_integrity_profile t10_pi_type3_ip = {
+const struct blk_integrity_profile t10_pi_type3_ip = {
.name = "T10-DIF-TYPE3-IP",
.generate_fn = t10_pi_type3_generate_ip,
.verify_fn = t10_pi_type3_verify_ip,