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Commit 1d9e9bc6 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-mq: don't stop queue for quiescing 



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.

Reviewed-by: default avatarBart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 69e07c4a

block/blk-mq.c

+3 −6
Original line number Original line Diff line number Diff line
@@ -169,11 +169,7 @@ void blk_mq_quiesce_queue(struct request_queue *q) 
	unsigned int i;

	unsigned int i;

	bool rcu = false;

	bool rcu = false;





	__blk_mq_stop_hw_queues(q, true);

	blk_mq_quiesce_queue_nowait(q);



	spin_lock_irq(q->queue_lock);

	queue_flag_set(QUEUE_FLAG_QUIESCED, q);

	spin_unlock_irq(q->queue_lock);





	queue_for_each_hw_ctx(q, hctx, i) {

	queue_for_each_hw_ctx(q, hctx, i) {

		if (hctx->flags & BLK_MQ_F_BLOCKING)

		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);

	queue_flag_clear(QUEUE_FLAG_QUIESCED, q);

	spin_unlock_irq(q->queue_lock);

	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);

EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);

include/linux/blk-mq.h

+0 −2
Original line number Original line Diff line number Diff line
@@ -271,8 +271,6 @@ static inline void blk_mq_quiesce_queue_nowait(struct request_queue *q) 
	spin_lock_irq(q->queue_lock);

	spin_lock_irq(q->queue_lock);

	queue_flag_set(QUEUE_FLAG_QUIESCED, q);

	queue_flag_set(QUEUE_FLAG_QUIESCED, q);

	spin_unlock_irq(q->queue_lock);

	spin_unlock_irq(q->queue_lock);



	blk_mq_stop_hw_queues(q);

}

}





/*

/*