Commit 02e70742 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-merge: fix blk_bio_segment_split

Commit bdced438(block: setup bi_phys_segments after
splitting) introduces function of computing bio->bi_phys_segments
during bio splitting.

Unfortunately both bio->bi_seg_front_size and bio->bi_seg_back_size
arn't computed, so too many physical segments may be obtained
for one request since both the two are used to check if one segment
across two bios can be possible.

This patch fixes the issue by computing the two variables in

Fixes: bdced438

(block: setup bi_phys_segments after splitting)
Reported-by: default avatarMichael Ellerman <>
Reported-by: default avatarMark Salter <>
Tested-by: default avatarLaurent Dufour <>
Tested-by: default avatarMark Salter <>
Signed-off-by: default avatarMing Lei <>
Signed-off-by: default avatarJens Axboe <>
parent 578270bf
......@@ -76,6 +76,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
struct bio_vec bv, bvprv, *bvprvp = NULL;
struct bvec_iter iter;
unsigned seg_size = 0, nsegs = 0, sectors = 0;
unsigned front_seg_size = bio->bi_seg_front_size;
bool do_split = true;
struct bio *new = NULL;
bio_for_each_segment(bv, bio, iter) {
if (sectors + (bv.bv_len >> 9) > queue_max_sectors(q))
......@@ -111,13 +114,26 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
bvprvp = &bvprv;
seg_size = bv.bv_len;
sectors += bv.bv_len >> 9;
if (nsegs == 1 && seg_size > front_seg_size)
front_seg_size = seg_size;
*segs = nsegs;
return NULL;
do_split = false;
*segs = nsegs;
return bio_split(bio, sectors, GFP_NOIO, bs);
if (do_split) {
new = bio_split(bio, sectors, GFP_NOIO, bs);
if (new)
bio = new;
bio->bi_seg_front_size = front_seg_size;
if (seg_size > bio->bi_seg_back_size)
bio->bi_seg_back_size = seg_size;
return do_split ? new : NULL;
void blk_queue_split(struct request_queue *q, struct bio **bio,
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