block: move sysfs_lock into elevator_init

Both callers take just around so function call, so move it in.
Also remove the now pointless blk_mq_sched_init wrapper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-core.c

@@ -1175,16 +1175,8 @@ int blk_init_allocated_queue(struct request_queue *q)
 
 	q->sg_reserved_size = INT_MAX;
 
-	/* Protect q->elevator from elevator_change */
-	mutex_lock(&q->sysfs_lock);
-
-	/* init elevator */
-	if (elevator_init(q)) {
-		mutex_unlock(&q->sysfs_lock);
+	if (elevator_init(q))
 		goto out_exit_flush_rq;
-	}
-
-	mutex_unlock(&q->sysfs_lock);
 	return 0;
 
 out_exit_flush_rq:

block/blk-mq-sched.c

@@ -647,14 +647,3 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
 	blk_mq_sched_tags_teardown(q);
 	q->elevator = NULL;
 }
-
-int blk_mq_sched_init(struct request_queue *q)
-{
-	int ret;
-
-	mutex_lock(&q->sysfs_lock);
-	ret = elevator_init(q);
-	mutex_unlock(&q->sysfs_lock);
-
-	return ret;
-}

block/blk-mq-sched.h

@@ -33,8 +33,6 @@ int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
 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);
-
 static inline bool
 blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
 {

block/blk-mq.c

@@ -2573,7 +2573,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
 		int ret;
 
-		ret = blk_mq_sched_init(q);
+		ret = elevator_init(q);
 		if (ret)
 			return ERR_PTR(ret);
 	}

block/elevator.c

@@ -202,16 +202,15 @@ static void elevator_release(struct kobject *kobj)
 int elevator_init(struct request_queue *q)
 {
 	struct elevator_type *e = NULL;
-	int err;
+	int err = 0;
 
 	/*
 	 * q->sysfs_lock must be held to provide mutual exclusion between
 	 * elevator_switch() and here.
 	 */
-	lockdep_assert_held(&q->sysfs_lock);
-
+	mutex_lock(&q->sysfs_lock);
 	if (unlikely(q->elevator))
-		return 0;
+		goto out_unlock;
 
 	/*
 	 * Use the default elevator specified by config boot param for
@@ -237,7 +236,7 @@ int elevator_init(struct request_queue *q)
 			if (q->nr_hw_queues == 1)
 				e = elevator_get(q, "mq-deadline", false);
 			if (!e)
-				return 0;
+				goto out_unlock;
 		} else
 			e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false);
 
@@ -255,6 +254,8 @@ int elevator_init(struct request_queue *q)
 		err = e->ops.sq.elevator_init_fn(q, e);
 	if (err)
 		elevator_put(e);
+out_unlock:
+	mutex_unlock(&q->sysfs_lock);
 	return err;
 }