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: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-merge.c b/block/blk-merge.c
index b3ac40a..89b97b5 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -97,19 +97,22 @@
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;
- if (no_sg_merge && !bio_flagged(bio, BIO_CLONED) &&
- merge_not_need)
- bio->bi_phys_segments = bio->bi_vcnt;
+ /* 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 (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;
}