diff mbox

[v4,09/11] blk-mq: don't stop queue for quiescing

Message ID 20170605155925.7896-10-ming.lei@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ming Lei June 5, 2017, 3:59 p.m. UTC 
Queue can be started by other blk-mq APIs and can be used in
different cases, this limits uses of blk_mq_quiesce_queue()
if it is based on stopping queue, and make its usage very
difficult, especially users have to use the stop queue APIs
carefully for avoiding to break blk_mq_quiesce_queue().

We have applied the QUIESCED flag for draining and blocking
dispatch, so it isn't necessary to stop queue any more.

After stopping queue is removed, blk_mq_quiesce_queue() can
be used safely and easily, then users won't worry about queue
restarting during quiescing at all.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-mq.c         | 9 +++------
 include/linux/blk-mq.h | 2 --
 2 files changed, 3 insertions(+), 8 deletions(-)

Comments

Bart Van Assche June 5, 2017, 9:36 p.m. UTC | #1 
On Mon, 2017-06-05 at 23:59 +0800, Ming Lei wrote:
> @@ -169,11 +169,7 @@ void blk_mq_quiesce_queue(struct request_queue *q)
>  	unsigned int i;
>  	bool rcu = false;
>  
> -	__blk_mq_stop_hw_queues(q, true);
> -
> -	spin_lock_irq(q->queue_lock);
> -	queue_flag_set(QUEUE_FLAG_QUIESCED, q);
> -	spin_unlock_irq(q->queue_lock);
> +	blk_mq_quiesce_queue_nowait(q);
>  

Although I would have preferred to keep blk_mq_quiesce_nowait() open-coded in
this function,

Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
diff mbox

Patch

diff --git a/block/blk-mq.c b/block/blk-mq.c
index c2177e8713ec..2788cacdaa1e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -169,11 +169,7 @@  void blk_mq_quiesce_queue(struct request_queue *q)
 	unsigned int i;
 	bool rcu = false;
 
-	__blk_mq_stop_hw_queues(q, true);
-
-	spin_lock_irq(q->queue_lock);
-	queue_flag_set(QUEUE_FLAG_QUIESCED, q);
-	spin_unlock_irq(q->queue_lock);
+	blk_mq_quiesce_queue_nowait(q);
 
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (hctx->flags & BLK_MQ_F_BLOCKING)
@@ -199,7 +195,8 @@  void blk_mq_unquiesce_queue(struct request_queue *q)
 	queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
 	spin_unlock_irq(q->queue_lock);
 
-	blk_mq_start_stopped_hw_queues(q, true);
+	/* dispatch requests which are inserted during quiescing */
+	blk_mq_run_hw_queues(q, true);
 }
 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
 
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index dc96ce3f5425..105d70630947 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -274,8 +274,6 @@  static inline void blk_mq_quiesce_queue_nowait(struct request_queue *q)
 	spin_lock_irq(q->queue_lock);
 	queue_flag_set(QUEUE_FLAG_QUIESCED, q);
 	spin_unlock_irq(q->queue_lock);
-
-	blk_mq_stop_hw_queues(q);
 }
 
 /*