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block: blk-merge: fix blk_recount_segments()

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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>
This commit is contained in:
Ming Lei 2014-11-12 00:15:41 +08:00 committed by Jens Axboe
parent 92697dc947
commit 7f60dcaaf9
1 changed files with 11 additions and 8 deletions
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19
block/blk-merge.c
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@ -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;
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;
}