path: root/block/blk-merge.c
diff options
authorMing Lei <tom.leiming@gmail.com>2014-10-22 08:30:30 +0800
committerJens Axboe <axboe@fb.com>2014-10-21 19:00:32 -0600
commit76d8137a31139f0d69ecc4177497ad6b8d4f016c (patch)
tree194c64bc760ff1aff6c21f29b9519725b1c2fc1a /block/blk-merge.c
parent432f16e64f50fd4999a476543d04dd52f7a2d753 (diff)
blk-merge: recaculate segment if it isn't less than max segments
The problem is introduced by commit 764f612c6c3c231b(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: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-merge.c')
1 files changed, 3 insertions, 2 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index ba99351c0f58..b3ac40aef46b 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -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 merge_not_need = bio->bi_vcnt < queue_max_segments(q);
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;
else {
struct bio *nxt = bio->bi_next;
bio->bi_next = NULL;
bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio,
- no_sg_merge);
+ no_sg_merge && merge_not_need);
bio->bi_next = nxt;