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Commit 76d8137a authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
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blk-merge: recaculate segment if it isn't less than max segments 



The problem is introduced by commit 764f612c(blk-merge:
don't compute bi_phys_segments from bi_vcnt for cloned bio),
and merge is needed if number of current segment isn't less than
max segments.

Strictly speaking, bio->bi_vcnt shouldn't be used here since
it may not be accurate in cases of both cloned bio or bio cloned
from, but bio_segments() is a bit expensive, and bi_vcnt is still
the biggest number, so the approach should work.

Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 432f16e6

block/blk-merge.c

+3 −2
Original line number Original line Diff line number Diff line
@@ -99,16 +99,17 @@ void blk_recount_segments(struct request_queue *q, struct bio *bio) 
{

{

	bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,

	bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,

			&q->queue_flags);

			&q->queue_flags);

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





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

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

			bio->bi_vcnt < queue_max_segments(q))

			merge_not_need)

		bio->bi_phys_segments = bio->bi_vcnt;

		bio->bi_phys_segments = bio->bi_vcnt;

	else {

	else {

		struct bio *nxt = bio->bi_next;

		struct bio *nxt = bio->bi_next;





		bio->bi_next = NULL;

		bio->bi_next = NULL;

		bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio,

		bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio,

				no_sg_merge);

				no_sg_merge && merge_not_need);

		bio->bi_next = nxt;

		bio->bi_next = nxt;

	}

	}