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Commit 7f60dcaa authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: blk-merge: fix blk_recount_segments() 



For cloned bio, bio->bi_vcnt can't be used at all, and we
have resort to bio_segments() to figure out how many
segment there are in the bio.

Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 92697dc9

block/blk-merge.c

+11 −8
Original line number Diff line number Diff line
@@ -97,19 +97,22 @@ void blk_recalc_rq_segments(struct request *rq) 


void blk_recount_segments(struct request_queue *q, struct bio *bio)

{

	bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,

			&q->queue_flags);

	bool merge_not_need = bio->bi_vcnt < queue_max_segments(q);

	unsigned short seg_cnt;



	/* estimate segment number by bi_vcnt for non-cloned bio */

	if (bio_flagged(bio, BIO_CLONED))

		seg_cnt = bio_segments(bio);

	else

		seg_cnt = bio->bi_vcnt;



	if (no_sg_merge && !bio_flagged(bio, BIO_CLONED) &&

			merge_not_need)

		bio->bi_phys_segments = bio->bi_vcnt;

	if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) &&

			(seg_cnt < queue_max_segments(q)))

		bio->bi_phys_segments = seg_cnt;

	else {

		struct bio *nxt = bio->bi_next;



		bio->bi_next = NULL;

		bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio,

				no_sg_merge && merge_not_need);

		bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false);

		bio->bi_next = nxt;

	}