blk-mq: don't stop queue for quiescing (1d9e9bc6) · Commits · 戴 / test

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:

Bart Van Assche <Bart.VanAssche@sandisk.com> Signed-off-by:

Ming Lei <ming.lei@redhat.com> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -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);

include/linux/blk-mq.h

+0 −2

Original line number	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);
		queue_flag_set(QUEUE_FLAG_QUIESCED, q);
		spin_unlock_irq(q->queue_lock);

		blk_mq_stop_hw_queues(q);
		}

		/*

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