From 23f3e3272e7a4d9fb870485cd6df1e4f9539282c Mon Sep 17 00:00:00 2001
From: Xiao Ni <xni@redhat.com>
Date: Thu, 9 Feb 2023 11:19:30 +0800
Subject: [PATCH] block: Merge bio before checking ->cached_rq
It checks if plug->cached_rq is empty before merging bio. But the merge action
doesn't have relationship with plug->cached_rq, it trys to merge bio with
requests within plug->mq_list. Now it checks if ->cached_rq is empty before
merging bio. If it's empty, it will miss the merge chances. So move the merge
function before checking ->cached_rq.
Signed-off-by: Xiao Ni <xni@redhat.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230209031930.27354-1-xni@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-mq.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 89b4dd81ae170..08093d4348dd6 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2879,15 +2879,16 @@ static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
if (!plug)
return NULL;
- rq = rq_list_peek(&plug->cached_rq);
- if (!rq || rq->q != q)
- return NULL;
if (blk_mq_attempt_bio_merge(q, *bio, nsegs)) {
*bio = NULL;
return NULL;
}
+ rq = rq_list_peek(&plug->cached_rq);
+ if (!rq || rq->q != q)
+ return NULL;
+
type = blk_mq_get_hctx_type((*bio)->bi_opf);
hctx_type = rq->mq_hctx->type;
if (type != hctx_type &&
--
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