From 7f60dcaaf91e911002007c7ae885ff6ef0f36c0d Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Wed, 12 Nov 2014 00:15:41 +0800 Subject: [PATCH] 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 Signed-off-by: Jens Axboe --- block/blk-merge.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index b3ac40aef46b..89b97b5e0881 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -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; + + /* 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 (no_sg_merge && !bio_flagged(bio, BIO_CLONED) && - merge_not_need) - bio->bi_phys_segments = 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; } -- 2.20.1