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blk-mq: update hctx->nr_active in blk_mq_end_request_batch()

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In case of shared tags and none io sched, batched completion still may
be run into, and hctx->nr_active is accounted when getting driver tag,
so it has to be updated in blk_mq_end_request_batch().

Otherwise, hctx->nr_active may become same with queue depth, then
hctx_may_queue() always return false, then io hang is caused.

Fixes the issue by updating the counter in batched way.

Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Fixes: f794f3351f ("block: add support for blk_mq_end_request_batch()")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20211102153619.3627505-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2021-11-02 23:36:19 +08:00 committed by Jens Axboe
parent 62ba0c008f
commit 3b87c6ea67
2 changed files with 16 additions and 3 deletions
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7
block/blk-mq.c
View file

@ -818,6 +818,13 @@ static inline void blk_mq_flush_tag_batch(struct blk_mq_hw_ctx *hctx,
{
struct request_queue *q = hctx->queue;
/*
* All requests should have been marked as RQF_MQ_INFLIGHT, so
* update hctx->nr_active in batch
*/
if (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
__blk_mq_sub_active_requests(hctx, nr_tags);
blk_mq_put_tags(hctx->tags, tag_array, nr_tags);
percpu_ref_put_many(&q->q_usage_counter, nr_tags);
}

12
block/blk-mq.h
View file

@ -225,12 +225,18 @@ static inline void __blk_mq_inc_active_requests(struct blk_mq_hw_ctx *hctx)
atomic_inc(&hctx->nr_active);
}
static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx)
static inline void __blk_mq_sub_active_requests(struct blk_mq_hw_ctx *hctx,
int val)
{
if (blk_mq_is_shared_tags(hctx->flags))
atomic_dec(&hctx->queue->nr_active_requests_shared_tags);
atomic_sub(val, &hctx->queue->nr_active_requests_shared_tags);
else
atomic_dec(&hctx->nr_active);
atomic_sub(val, &hctx->nr_active);
}
static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx)
{
__blk_mq_sub_active_requests(hctx, 1);
}
static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx)