[PATCHv3 1/2] block: move elevator queue allocation logic into blk_mq_init_sched

[Nilay Shroff <nilay@linux.ibm.com>]

In preparation for allocating sched_tags before freezing the request
queue and acquiring ->elevator_lock, move the elevator queue allocation
logic from the elevator ops ->init_sched callback into blk_mq_init_sched.

This refactoring provides a centralized location for elevator queue
initialization, which makes it easier to store pre-allocated sched_tags
in the struct elevator_queue during later changes.

Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
---
 block/bfq-iosched.c   | 13 +++----------
 block/blk-mq-sched.c  |  7 ++++++-
 block/elevator.h      |  2 +-
 block/kyber-iosched.c | 11 ++---------
 block/mq-deadline.c   | 14 ++------------
 5 files changed, 14 insertions(+), 33 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 0cb1e9873aab..fd26dc1901b0 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -7232,22 +7232,16 @@ static void bfq_init_root_group(struct bfq_group *root_group,
 	root_group->sched_data.bfq_class_idle_last_service = jiffies;
 }
 
-static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
+static int bfq_init_queue(struct request_queue *q, struct elevator_queue *eq)
 {
 	struct bfq_data *bfqd;
-	struct elevator_queue *eq;
 	unsigned int i;
 	struct blk_independent_access_ranges *ia_ranges = q->disk->ia_ranges;
 
-	eq = elevator_alloc(q, e);
-	if (!eq)
-		return -ENOMEM;
-
 	bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
-	if (!bfqd) {
-		kobject_put(&eq->kobj);
+	if (!bfqd)
 		return -ENOMEM;
-	}
+
 	eq->elevator_data = bfqd;
 
 	spin_lock_irq(&q->queue_lock);
@@ -7405,7 +7399,6 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
 
 out_free:
 	kfree(bfqd);
-	kobject_put(&eq->kobj);
 	return -ENOMEM;
 }
 
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 55a0fd105147..d914eb9d61a6 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -475,6 +475,10 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 	q->nr_requests = 2 * min_t(unsigned int, q->tag_set->queue_depth,
 				   BLKDEV_DEFAULT_RQ);
 
+	eq = elevator_alloc(q, e);
+	if (!eq)
+		return -ENOMEM;
+
 	if (blk_mq_is_shared_tags(flags)) {
 		ret = blk_mq_init_sched_shared_tags(q);
 		if (ret)
@@ -487,7 +491,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 			goto err_free_map_and_rqs;
 	}
 
-	ret = e->ops.init_sched(q, e);
+	ret = e->ops.init_sched(q, eq);
 	if (ret)
 		goto err_free_map_and_rqs;
 
@@ -509,6 +513,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 	blk_mq_sched_free_rqs(q);
 	blk_mq_sched_tags_teardown(q, flags);
 
+	kobject_put(&eq->kobj);
 	q->elevator = NULL;
 	return ret;
 }
diff --git a/block/elevator.h b/block/elevator.h
index a07ce773a38f..a4de5f9ad790 100644
--- a/block/elevator.h
+++ b/block/elevator.h
@@ -24,7 +24,7 @@ struct blk_mq_alloc_data;
 struct blk_mq_hw_ctx;
 
 struct elevator_mq_ops {
-	int (*init_sched)(struct request_queue *, struct elevator_type *);
+	int (*init_sched)(struct request_queue *, struct elevator_queue *);
 	void (*exit_sched)(struct elevator_queue *);
 	int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
 	void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index 4dba8405bd01..7b6832cb3a8d 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -402,20 +402,13 @@ static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q)
 	return ERR_PTR(ret);
 }
 
-static int kyber_init_sched(struct request_queue *q, struct elevator_type *e)
+static int kyber_init_sched(struct request_queue *q, struct elevator_queue *eq)
 {
 	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);
+	if (IS_ERR(kqd))
 		return PTR_ERR(kqd);
-	}
 
 	blk_stat_enable_accounting(q);
 
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 2edf1cac06d5..7b6caf30e00a 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -568,20 +568,14 @@ static void dd_exit_sched(struct elevator_queue *e)
 /*
  * initialize elevator private data (deadline_data).
  */
-static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
+static int dd_init_sched(struct request_queue *q, struct elevator_queue *eq)
 {
 	struct deadline_data *dd;
-	struct elevator_queue *eq;
 	enum dd_prio prio;
-	int ret = -ENOMEM;
-
-	eq = elevator_alloc(q, e);
-	if (!eq)
-		return ret;
 
 	dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
 	if (!dd)
-		goto put_eq;
+		return -ENOMEM;
 
 	eq->elevator_data = dd;
 
@@ -608,10 +602,6 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
 
 	q->elevator = eq;
 	return 0;
-
-put_eq:
-	kobject_put(&eq->kobj);
-	return ret;
 }
 
 /*
-- 
2.49.0