From: Ming Lei <ming.lei@redhat.com>
Date: Thu, 11 Nov 2021 16:51:33 +0800
Subject: [PATCH] blk-mq: don't grab ->q_usage_counter in
blk_mq_sched_bio_merge
Git-commit: 10f7335e3627b4efa341ef8ac457f2c0770c5c19
Patch-mainline: v5.16-rc1
References: jsc#PED-1183
blk_mq_sched_bio_merge is only called from blk-mq.c:blk_attempt_bio_merge(),
which is called when queue usage counter is grabbed already:
1) blk_mq_get_new_requests()
2) blk_mq_get_request()
- cached request in current plug owns one queue usage counter
So don't grab ->q_usage_counter in blk_mq_sched_bio_merge(), and more
importantly this nest way causes hang in blk_mq_freeze_queue_wait().
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211111085134.345235-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
block/blk-mq-sched.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 4be652fa38e7..ba21449439cc 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -370,9 +370,6 @@ bool blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
bool ret = false;
enum hctx_type type;
- if (bio_queue_enter(bio))
- return false;
-
if (e && e->type->ops.bio_merge) {
ret = e->type->ops.bio_merge(q, bio, nr_segs);
goto out_put;
@@ -397,7 +394,6 @@ bool blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
spin_unlock(&ctx->lock);
out_put:
- blk_queue_exit(q);
return ret;
}
--
2.35.3