block: remove __elevator_change

[Christoph Hellwig <hch@xxxxxx>]

elv_update_nr_hw_queues is very different from the other elevator
change cases, so open code the logic there.  Move the lookup of the
elevator type into elevator_switch to simplify this a bit.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 block/elevator.c | 73 ++++++++++++++++++++----------------------------
 1 file changed, 30 insertions(+), 43 deletions(-)

diff --git a/block/elevator.c b/block/elevator.c
index 71329a73bb44..e51f7b8bad16 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -56,7 +56,6 @@ static LIST_HEAD(elv_list);
 /* Holding context data for changing elevator */
 struct elv_change_ctx {
 	const char *name;
-	bool force;
 	bool uevent;
 	bool init;
 
@@ -644,11 +643,15 @@ void elevator_set_none(struct request_queue *q)
  * If switching fails, we are most likely running out of memory and not able
  * to restore the old io scheduler, so leaving the io scheduler being none.
  */
-static int elevator_switch(struct request_queue *q, struct elevator_type *new_e,
-			   struct elv_change_ctx *ctx)
+static int elevator_switch(struct request_queue *q, struct elv_change_ctx *ctx)
 {
+	struct elevator_type *new_e;
 	int ret;
 
+	new_e = elevator_find_get(ctx->name);
+	if (!new_e)
+		return -EINVAL;
+
 	WARN_ON_ONCE(q->mq_freeze_depth == 0);
 	lockdep_assert_held(&q->elevator_lock);
 
@@ -674,6 +677,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e,
 			new_e->elevator_name);
 	}
 
+	elevator_put(new_e);
 	return ret;
 }
 
@@ -723,38 +727,6 @@ static int elevator_change_done(struct request_queue *q,
 	return 0;
 }
 
-/*
- * Switch this queue to the given IO scheduler.
- */
-static int __elevator_change(struct request_queue *q,
-		struct elv_change_ctx *ctx)
-{
-	const char *elevator_name = ctx->name;
-	struct elevator_type *e;
-	int ret;
-
-	/* Make sure queue is not in the middle of being removed */
-	if (!ctx->init && !blk_queue_registered(q))
-		return -ENOENT;
-
-	if (!strncmp(elevator_name, "none", 4)) {
-		if (q->elevator)
-			elevator_disable(q, ctx);
-		return 0;
-	}
-
-	if (!ctx->force && q->elevator &&
-	    elevator_match(q->elevator->type, elevator_name))
-		return 0;
-
-	e = elevator_find_get(elevator_name);
-	if (!e)
-		return -EINVAL;
-	ret = elevator_switch(q, e, ctx);
-	elevator_put(e);
-	return ret;
-}
-
 /*
  * The I/O scheduler depends on the number of hardware queues, this forces a
  * reattachment when nr_hw_queues changes.
@@ -764,19 +736,25 @@ static int __elevator_change(struct request_queue *q,
 void elv_update_nr_hw_queues(struct request_queue *q)
 {
 	struct elv_change_ctx ctx = {
-		.name	= "none",
-		.force	= true,
 		.uevent	= true,
 	};
-	int ret;
+	bool done = false;
 
 	mutex_lock(&q->elevator_lock);
-	if (q->elevator && !blk_queue_dying(q))
+	if (!blk_queue_registered(q))
+		goto out_unlock;
+
+	if (q->elevator) {
 		ctx.name = q->elevator->type->elevator_name;
-	ret = __elevator_change(q, &ctx);
+		if (elevator_switch(q, &ctx) == 0)
+			done = true;
+	}
+
+out_unlock:
 	mutex_unlock(&q->elevator_lock);
 	blk_mq_unfreeze_queue_nomemrestore(q);
-	if (!ret)
+
+	if (done)
 		WARN_ON_ONCE(elevator_change_done(q, &ctx));
 }
 
@@ -785,7 +763,7 @@ static int elevator_change(struct request_queue *q,
 {
 	struct blk_mq_tag_set *set = q->tag_set;
 	unsigned int memflags;
-	int ret, idx;
+	int ret = 0, idx;
 
 	idx = srcu_read_lock(&set->update_nr_hwq_srcu);
 	if (set->updating_nr_hwq) {
@@ -805,7 +783,16 @@ static int elevator_change(struct request_queue *q,
 	 */
 	blk_mq_cancel_work_sync(q);
 	mutex_lock(&q->elevator_lock);
-	ret = __elevator_change(q, ctx);
+	/* Make sure queue is not in the middle of being removed */
+	if (!ctx->init && !blk_queue_registered(q)) {
+		ret = -ENOENT;
+	} else if (!strncmp(ctx->name, "none", 4)) {
+		if (q->elevator)
+			elevator_disable(q, ctx);
+	} else if (!q->elevator ||
+		   !elevator_match(q->elevator->type, ctx->name)) {
+		ret = elevator_switch(q, ctx);
+	}
 	mutex_unlock(&q->elevator_lock);
 	blk_mq_unfreeze_queue(q, memflags);
 	if (!ret)
-- 
2.47.2


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