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Commit 454be724 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: drain queue before waiting for q_usage_counter becoming zero 

Now we track legacy requests with .q_usage_counter in commit 055f6e18
("block: Make q_usage_counter also track legacy requests"), but that
commit never runs and drains legacy queue before waiting for this counter
becoming zero, then IO hang is caused in the test of pulling disk during IO.

This patch fixes the issue by draining requests before waiting for
q_usage_counter becoming zero, both Mauricio and chenxiang reported this
issue, and observed that it can be fixed by this patch.

Link: https://marc.info/?l=linux-block&m=151192424731797&w=2


Fixes: 055f6e18("block: Make q_usage_counter also track legacy requests")
Cc: Wen Xiong <wenxiong@us.ibm.com>
Tested-by: default avatar"chenxiang (M)" <chenxiang66@hisilicon.com>
Tested-by: default avatarMauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 6d0e4827

block/blk-core.c

+7 −2
Original line number Diff line number Diff line
@@ -562,6 +562,13 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all) 
	}

}



void blk_drain_queue(struct request_queue *q)

{

	spin_lock_irq(q->queue_lock);

	__blk_drain_queue(q, true);

	spin_unlock_irq(q->queue_lock);

}



/**

 * blk_queue_bypass_start - enter queue bypass mode

 * @q: queue of interest
@@ -689,8 +696,6 @@ void blk_cleanup_queue(struct request_queue *q) 
	 */

	blk_freeze_queue(q);

	spin_lock_irq(lock);

	if (!q->mq_ops)

		__blk_drain_queue(q, true);

	queue_flag_set(QUEUE_FLAG_DEAD, q);

	spin_unlock_irq(lock);

block/blk-mq.c

+2 −0
Original line number Diff line number Diff line
@@ -161,6 +161,8 @@ void blk_freeze_queue(struct request_queue *q) 
	 * exported to drivers as the only user for unfreeze is blk_mq.

	 */

	blk_freeze_queue_start(q);

	if (!q->mq_ops)

		blk_drain_queue(q);

	blk_mq_freeze_queue_wait(q);

}

block/blk.h

+2 −0
Original line number Diff line number Diff line
@@ -330,4 +330,6 @@ static inline void blk_queue_bounce(struct request_queue *q, struct bio **bio) 
}

#endif /* CONFIG_BOUNCE */



extern void blk_drain_queue(struct request_queue *q);



#endif /* BLK_INTERNAL_H */