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blk-mq: don't stop queue for quiescing

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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>
This commit is contained in:
Ming Lei 2017-06-06 23:22:08 +08:00 committed by Jens Axboe
parent 69e07c4adb
commit 1d9e9bc6b5
2 changed files with 3 additions and 8 deletions
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9
block/blk-mq.c
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@ -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);

2
include/linux/blk-mq.h
View File

@ -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);
}
/*