On 11/22/2017 06:11 AM, Ming Lei wrote:
> Now we track legacy requests with .q_usage_counter in commit 055f6e18e08f
> ("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.
>
> Fixes: 055f6e18e08f("block: Make q_usage_counter also track legacy requests")
> Cc: Wen Xiong <wenxiong@xxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> block/blk-core.c | 9 +++++++--
> block/blk-mq.c | 2 ++
> block/blk.h | 2 ++
> 3 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 1038706edd87..5ae5ea0dca4c 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -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);
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 11097477eeab..3d3797327491 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -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);
> }
>
> diff --git a/block/blk.h b/block/blk.h
> index 3f1446937aec..442098aa9463 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -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 */
>
I seem to have missed something.
Is blk_drain_queue() ever used?
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
