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-rw-r--r--drivers/block/drbd/drbd_actlog.c15
-rw-r--r--drivers/block/drbd/drbd_req.c136
2 files changed, 98 insertions, 53 deletions
diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index 6ce5c76d642b..e9fbcafaccdc 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -357,8 +357,19 @@ int drbd_al_begin_io_nonblock(struct drbd_device *device, struct drbd_interval *
/* We want all necessary updates for a given request within the same transaction
* We could first check how many updates are *actually* needed,
* and use that instead of the worst-case nr_al_extents */
- if (available_update_slots < nr_al_extents)
- return -EWOULDBLOCK;
+ if (available_update_slots < nr_al_extents) {
+ /* Too many activity log extents are currently "hot".
+ *
+ * If we have accumulated pending changes already,
+ * we made progress.
+ *
+ * If we cannot get even a single pending change through,
+ * stop the fast path until we made some progress,
+ * or requests to "cold" extents could be starved. */
+ if (!al->pending_changes)
+ __set_bit(__LC_STARVING, &device->act_log->flags);
+ return -ENOBUFS;
+ }
/* Is resync active in this area? */
for (enr = first; enr <= last; enr++) {
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 74ebef101dc7..c67717d572d1 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1182,6 +1182,8 @@ static void drbd_queue_write(struct drbd_device *device, struct drbd_request *re
&device->pending_master_completion[1 /* WRITE */]);
spin_unlock_irq(&device->resource->req_lock);
queue_work(device->submit.wq, &device->submit.worker);
+ /* do_submit() may sleep internally on al_wait, too */
+ wake_up(&device->al_wait);
}
/* returns the new drbd_request pointer, if the caller is expected to
@@ -1365,7 +1367,8 @@ static void submit_fast_path(struct drbd_device *device, struct list_head *incom
static bool prepare_al_transaction_nonblock(struct drbd_device *device,
struct list_head *incoming,
- struct list_head *pending)
+ struct list_head *pending,
+ struct list_head *later)
{
struct drbd_request *req, *tmp;
int wake = 0;
@@ -1374,44 +1377,105 @@ static bool prepare_al_transaction_nonblock(struct drbd_device *device,
spin_lock_irq(&device->al_lock);
list_for_each_entry_safe(req, tmp, incoming, tl_requests) {
err = drbd_al_begin_io_nonblock(device, &req->i);
+ if (err == -ENOBUFS)
+ break;
if (err == -EBUSY)
wake = 1;
if (err)
- continue;
- list_move_tail(&req->tl_requests, pending);
+ list_move_tail(&req->tl_requests, later);
+ else
+ list_move_tail(&req->tl_requests, pending);
}
spin_unlock_irq(&device->al_lock);
if (wake)
wake_up(&device->al_wait);
-
return !list_empty(pending);
}
+void send_and_submit_pending(struct drbd_device *device, struct list_head *pending)
+{
+ struct drbd_request *req, *tmp;
+
+ list_for_each_entry_safe(req, tmp, pending, tl_requests) {
+ req->rq_state |= RQ_IN_ACT_LOG;
+ req->in_actlog_jif = jiffies;
+ atomic_dec(&device->ap_actlog_cnt);
+ list_del_init(&req->tl_requests);
+ drbd_send_and_submit(device, req);
+ }
+}
+
void do_submit(struct work_struct *ws)
{
struct drbd_device *device = container_of(ws, struct drbd_device, submit.worker);
- LIST_HEAD(incoming);
- LIST_HEAD(pending);
- struct drbd_request *req, *tmp;
+ LIST_HEAD(incoming); /* from drbd_make_request() */
+ LIST_HEAD(pending); /* to be submitted after next AL-transaction commit */
+ LIST_HEAD(busy); /* blocked by resync requests */
+
+ /* grab new incoming requests */
+ spin_lock_irq(&device->resource->req_lock);
+ list_splice_tail_init(&device->submit.writes, &incoming);
+ spin_unlock_irq(&device->resource->req_lock);
for (;;) {
- spin_lock_irq(&device->resource->req_lock);
- list_splice_tail_init(&device->submit.writes, &incoming);
- spin_unlock_irq(&device->resource->req_lock);
+ DEFINE_WAIT(wait);
+ /* move used-to-be-busy back to front of incoming */
+ list_splice_init(&busy, &incoming);
submit_fast_path(device, &incoming);
if (list_empty(&incoming))
break;
-skip_fast_path:
- wait_event(device->al_wait, prepare_al_transaction_nonblock(device, &incoming, &pending));
- /* Maybe more was queued, while we prepared the transaction?
- * Try to stuff them into this transaction as well.
- * Be strictly non-blocking here, no wait_event, we already
- * have something to commit.
- * Stop if we don't make any more progres.
- */
for (;;) {
+ prepare_to_wait(&device->al_wait, &wait, TASK_UNINTERRUPTIBLE);
+
+ list_splice_init(&busy, &incoming);
+ prepare_al_transaction_nonblock(device, &incoming, &pending, &busy);
+ if (!list_empty(&pending))
+ break;
+
+ schedule();
+
+ /* If all currently "hot" activity log extents are kept busy by
+ * incoming requests, we still must not totally starve new
+ * requests to "cold" extents.
+ * Something left on &incoming means there had not been
+ * enough update slots available, and the activity log
+ * has been marked as "starving".
+ *
+ * Try again now, without looking for new requests,
+ * effectively blocking all new requests until we made
+ * at least _some_ progress with what we currently have.
+ */
+ if (!list_empty(&incoming))
+ continue;
+
+ /* Nothing moved to pending, but nothing left
+ * on incoming: all moved to busy!
+ * Grab new and iterate. */
+ spin_lock_irq(&device->resource->req_lock);
+ list_splice_tail_init(&device->submit.writes, &incoming);
+ spin_unlock_irq(&device->resource->req_lock);
+ }
+ finish_wait(&device->al_wait, &wait);
+
+ /* If the transaction was full, before all incoming requests
+ * had been processed, skip ahead to commit, and iterate
+ * without splicing in more incoming requests from upper layers.
+ *
+ * Else, if all incoming have been processed,
+ * they have become either "pending" (to be submitted after
+ * next transaction commit) or "busy" (blocked by resync).
+ *
+ * Maybe more was queued, while we prepared the transaction?
+ * Try to stuff those into this transaction as well.
+ * Be strictly non-blocking here,
+ * we already have something to commit.
+ *
+ * Commit if we don't make any more progres.
+ */
+
+ while (list_empty(&incoming)) {
LIST_HEAD(more_pending);
LIST_HEAD(more_incoming);
bool made_progress;
@@ -1428,46 +1492,16 @@ skip_fast_path:
if (list_empty(&more_incoming))
break;
- made_progress = prepare_al_transaction_nonblock(device, &more_incoming, &more_pending);
+ made_progress = prepare_al_transaction_nonblock(device, &more_incoming, &more_pending, &busy);
list_splice_tail_init(&more_pending, &pending);
list_splice_tail_init(&more_incoming, &incoming);
-
if (!made_progress)
break;
}
- drbd_al_begin_io_commit(device);
- list_for_each_entry_safe(req, tmp, &pending, tl_requests) {
- req->rq_state |= RQ_IN_ACT_LOG;
- req->in_actlog_jif = jiffies;
- atomic_dec(&device->ap_actlog_cnt);
- list_del_init(&req->tl_requests);
- drbd_send_and_submit(device, req);
- }
-
- /* If all currently hot activity log extents are kept busy by
- * incoming requests, we still must not totally starve new
- * requests to cold extents. In that case, prepare one request
- * in blocking mode. */
- list_for_each_entry_safe(req, tmp, &incoming, tl_requests) {
- bool was_cold;
- list_del_init(&req->tl_requests);
- was_cold = drbd_al_begin_io_prepare(device, &req->i);
- if (!was_cold) {
- req->rq_state |= RQ_IN_ACT_LOG;
- req->in_actlog_jif = jiffies;
- atomic_dec(&device->ap_actlog_cnt);
- /* Corresponding extent was hot after all? */
- drbd_send_and_submit(device, req);
- } else {
- /* Found a request to a cold extent.
- * Put on "pending" list,
- * and try to cumulate with more. */
- list_add(&req->tl_requests, &pending);
- goto skip_fast_path;
- }
- }
+ drbd_al_begin_io_commit(device);
+ send_and_submit_pending(device, &pending);
}
}
generated by cgit (git 2.34.1) at 2024-06-23 22:17:48 +0000