Commit 23f3e327 authored by Xiao Ni's avatar Xiao Ni Committed by Jens Axboe
Browse files

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: default avatarXiao Ni <xni@redhat.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230209031930.27354-1-xni@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent dcb52201

block/blk-mq.c

+4 −3
Original line number Diff line number Diff line
@@ -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 &&