Commit 2dc5f68f authored Jan 18, 2023 by Kemeng Shi Committed by Greg Kroah-Hartman Mar 11, 2023

blk-mq: wait on correct sbitmap_queue in blk_mq_mark_tag_wait



[ Upstream commit 98b99e9412d0cde8c7b442bf5efb09528a2ede8b ]

For shared queues case, we will only wait on bitmap_tags if we fail to get
driver tag. However, rq could be from breserved_tags, then two problems
will occur:
1. io hung if no tag is currently allocated from bitmap_tags.
2. unnecessary wakeup when tag is freed to bitmap_tags while no tag is
freed to breserved_tags.
Wait on the bitmap which rq from to fix this.

Fixes: f906a6a0 ("blk-mq: improve tag waiting setup for non-shared tags")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 8c225150

block/blk-mq.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -1112,7 +1112,7 @@ static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
		static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
		struct request *rq)
		{
		struct sbitmap_queue *sbq = &hctx->tags->bitmap_tags;
		struct sbitmap_queue *sbq;
		struct wait_queue_head *wq;
		wait_queue_entry_t *wait;
		bool ret;
		@@ -1135,6 +1135,10 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
		if (!list_empty_careful(&wait->entry))
		return false;

		if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag))
		sbq = &hctx->tags->breserved_tags;
		else
		sbq = &hctx->tags->bitmap_tags;
		wq = &bt_wait_ptr(sbq, hctx)->wait;

		spin_lock_irq(&wq->lock);