1 files changed, 50 insertions, 82 deletions

diff --git a/block/elevator.c b/block/elevator.c
index 5ff093cb3cf8..cd2ce4921601 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -83,13 +83,6 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
 }
 EXPORT_SYMBOL(elv_bio_merge_ok);
 
-static inline bool elv_support_features(struct request_queue *q,
-		const struct elevator_type *e)
-{
-	return (q->required_elevator_features & e->elevator_features) ==
-		q->required_elevator_features;
-}
-
 /**
  * elevator_match - Check whether @e's name or alias matches @name
  * @e: Scheduler to test
@@ -113,14 +106,13 @@ static struct elevator_type *__elevator_find(const char *name)
 	return NULL;
 }
 
-static struct elevator_type *elevator_find_get(struct request_queue *q,
-		const char *name)
+static struct elevator_type *elevator_find_get(const char *name)
 {
 	struct elevator_type *e;
 
 	spin_lock(&elv_list_lock);
 	e = __elevator_find(name);
-	if (e && (!elv_support_features(q, e) || !elevator_tryget(e)))
+	if (e && (!elevator_tryget(e)))
 		e = NULL;
 	spin_unlock(&elv_list_lock);
 	return e;
@@ -413,12 +405,12 @@ struct request *elv_former_request(struct request_queue *q, struct request *rq)
 	return NULL;
 }
 
-#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
+#define to_elv(atr) container_of_const((atr), struct elv_fs_entry, attr)
 
 static ssize_t
 elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 {
-	struct elv_fs_entry *entry = to_elv(attr);
+	const struct elv_fs_entry *entry = to_elv(attr);
 	struct elevator_queue *e;
 	ssize_t error;
 
@@ -436,7 +428,7 @@ static ssize_t
 elv_attr_store(struct kobject *kobj, struct attribute *attr,
 	       const char *page, size_t length)
 {
-	struct elv_fs_entry *entry = to_elv(attr);
+	const struct elv_fs_entry *entry = to_elv(attr);
 	struct elevator_queue *e;
 	ssize_t error;
 
@@ -469,7 +461,7 @@ int elv_register_queue(struct request_queue *q, bool uevent)
 
 	error = kobject_add(&e->kobj, &q->disk->queue_kobj, "iosched");
 	if (!error) {
-		struct elv_fs_entry *attr = e->type->elevator_attrs;
+		const struct elv_fs_entry *attr = e->type->elevator_attrs;
 		if (attr) {
 			while (attr->attr.name) {
 				if (sysfs_create_file(&e->kobj, &attr->attr))
@@ -555,77 +547,38 @@ void elv_unregister(struct elevator_type *e)
 }
 EXPORT_SYMBOL_GPL(elv_unregister);
 
-static inline bool elv_support_iosched(struct request_queue *q)
-{
-	if (!queue_is_mq(q) ||
-	    (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED)))
-		return false;
-	return true;
-}
-
 /*
  * For single queue devices, default to using mq-deadline. If we have multiple
  * queues or mq-deadline is not available, default to "none".
  */
 static struct elevator_type *elevator_get_default(struct request_queue *q)
 {
-	if (q->tag_set && q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT)
+	if (q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT)
 		return NULL;
 
 	if (q->nr_hw_queues != 1 &&
 	    !blk_mq_is_shared_tags(q->tag_set->flags))
 		return NULL;
 
-	return elevator_find_get(q, "mq-deadline");
-}
-
-/*
- * Get the first elevator providing the features required by the request queue.
- * Default to "none" if no matching elevator is found.
- */
-static struct elevator_type *elevator_get_by_features(struct request_queue *q)
-{
-	struct elevator_type *e, *found = NULL;
-
-	spin_lock(&elv_list_lock);
-
-	list_for_each_entry(e, &elv_list, list) {
-		if (elv_support_features(q, e)) {
-			found = e;
-			break;
-		}
-	}
-
-	if (found && !elevator_tryget(found))
-		found = NULL;
-
-	spin_unlock(&elv_list_lock);
-	return found;
+	return elevator_find_get("mq-deadline");
 }
 
 /*
- * For a device queue that has no required features, use the default elevator
- * settings. Otherwise, use the first elevator available matching the required
- * features. If no suitable elevator is find or if the chosen elevator
- * initialization fails, fall back to the "none" elevator (no elevator).
+ * Use the default elevator settings. If the chosen elevator initialization
+ * fails, fall back to the "none" elevator (no elevator).
  */
 void elevator_init_mq(struct request_queue *q)
 {
 	struct elevator_type *e;
+	unsigned int memflags;
 	int err;
 
-	if (!elv_support_iosched(q))
-		return;
-
 	WARN_ON_ONCE(blk_queue_registered(q));
 
 	if (unlikely(q->elevator))
 		return;
 
-	if (!q->required_elevator_features)
-		e = elevator_get_default(q);
-	else
-		e = elevator_get_by_features(q);
+	e = elevator_get_default(q);
 	if (!e)
 		return;
 
@@ -635,13 +588,16 @@ void elevator_init_mq(struct request_queue *q)
 	 * drain any dispatch activities originated from passthrough
 	 * requests, then no need to quiesce queue which may add long boot
 	 * latency, especially when lots of disks are involved.
+	 *
+	 * Disk isn't added yet, so verifying queue lock only manually.
 	 */
-	blk_mq_freeze_queue(q);
+	memflags = blk_mq_freeze_queue(q);
+
 	blk_mq_cancel_work_sync(q);
 
 	err = blk_mq_init_sched(q, e);
 
-	blk_mq_unfreeze_queue(q);
+	blk_mq_unfreeze_queue(q, memflags);
 
 	if (err) {
 		pr_warn("\"%s\" elevator initialization failed, "
@@ -659,11 +615,12 @@ void elevator_init_mq(struct request_queue *q)
  */
 int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 {
+	unsigned int memflags;
 	int ret;
 
 	lockdep_assert_held(&q->sysfs_lock);
 
-	blk_mq_freeze_queue(q);
+	memflags = blk_mq_freeze_queue(q);
 	blk_mq_quiesce_queue(q);
 
 	if (q->elevator) {
@@ -684,7 +641,7 @@ int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 
 out_unfreeze:
 	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q);
+	blk_mq_unfreeze_queue(q, memflags);
 
 	if (ret) {
 		pr_warn("elv: switch to \"%s\" failed, falling back to \"none\"\n",
@@ -696,9 +653,11 @@ out_unfreeze:
 
 void elevator_disable(struct request_queue *q)
 {
+	unsigned int memflags;
+
 	lockdep_assert_held(&q->sysfs_lock);
 
-	blk_mq_freeze_queue(q);
+	memflags = blk_mq_freeze_queue(q);
 	blk_mq_quiesce_queue(q);
 
 	elv_unregister_queue(q);
@@ -709,7 +668,7 @@ void elevator_disable(struct request_queue *q)
 	blk_add_trace_msg(q, "elv switch: none");
 
 	blk_mq_unquiesce_queue(q);
-	blk_mq_unfreeze_queue(q);
+	blk_mq_unfreeze_queue(q, memflags);
 }
 
 /*
@@ -733,43 +692,52 @@ static int elevator_change(struct request_queue *q, const char *elevator_name)
 	if (q->elevator && elevator_match(q->elevator->type, elevator_name))
 		return 0;
 
-	e = elevator_find_get(q, elevator_name);
-	if (!e) {
-		request_module("%s-iosched", elevator_name);
-		e = elevator_find_get(q, elevator_name);
-		if (!e)
-			return -EINVAL;
-	}
+	e = elevator_find_get(elevator_name);
+	if (!e)
+		return -EINVAL;
 	ret = elevator_switch(q, e);
 	elevator_put(e);
 	return ret;
 }
 
-ssize_t elv_iosched_store(struct request_queue *q, const char *buf,
+void elv_iosched_load_module(struct gendisk *disk, const char *buf,
+			     size_t count)
+{
+	char elevator_name[ELV_NAME_MAX];
+	struct elevator_type *found;
+	const char *name;
+
+	strscpy(elevator_name, buf, sizeof(elevator_name));
+	name = strstrip(elevator_name);
+
+	spin_lock(&elv_list_lock);
+	found = __elevator_find(name);
+	spin_unlock(&elv_list_lock);
+
+	if (!found)
+		request_module("%s-iosched", name);
+}
+
+ssize_t elv_iosched_store(struct gendisk *disk, const char *buf,
 			  size_t count)
 {
 	char elevator_name[ELV_NAME_MAX];
 	int ret;
 
-	if (!elv_support_iosched(q))
-		return count;
-
 	strscpy(elevator_name, buf, sizeof(elevator_name));
-	ret = elevator_change(q, strstrip(elevator_name));
+	ret = elevator_change(disk->queue, strstrip(elevator_name));
 	if (!ret)
 		return count;
 	return ret;
 }
 
-ssize_t elv_iosched_show(struct request_queue *q, char *name)
+ssize_t elv_iosched_show(struct gendisk *disk, char *name)
 {
+	struct request_queue *q = disk->queue;
 	struct elevator_queue *eq = q->elevator;
 	struct elevator_type *cur = NULL, *e;
 	int len = 0;
 
-	if (!elv_support_iosched(q))
-		return sprintf(name, "none\n");
-
 	if (!q->elevator) {
 		len += sprintf(name+len, "[none] ");
 	} else {
@@ -781,7 +749,7 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
 	list_for_each_entry(e, &elv_list, list) {
 		if (e == cur)
 			len += sprintf(name+len, "[%s] ", e->elevator_name);
-		else if (elv_support_features(q, e))
+		else
 			len += sprintf(name+len, "%s ", e->elevator_name);
 	}
 	spin_unlock(&elv_list_lock);