Commit 3b87c6ea authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

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



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: default avatarShinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Fixes: f794f335 ("block: add support for blk_mq_end_request_batch()")
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20211102153619.3627505-4-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 62ba0c00

block/blk-mq.c

+7 −0
Original line number Diff line number Diff line
@@ -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);

}

block/blk-mq.h

+9 −3
Original line number Diff line number Diff line
@@ -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)