From 9523e3194ca0497e9cd88bc05d516002e33cc9c4 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 19 Mar 2019 15:47:46 +0800 Subject: [PATCH] block: don't use bio->bi_vcnt to figure out segment number mainline inclusion from mainline-5.1-rc1 commit 1a67356e9a4829da2935dd338630a550c59c8489 category: bugfix bugzilla: 12057 CVE: NA --------------------------- It is wrong to use bio->bi_vcnt to figure out how many segments there are in the bio even though CLONED flag isn't set on this bio, because this bio may be splitted or advanced. So always use bio_segments() in blk_recount_segments(), and it shouldn't cause any performance loss now because the physical segment number is figured out in blk_queue_split() and BIO_SEG_VALID is set meantime since bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting"). Reviewed-by: Omar Sandoval Reviewed-by: Christoph Hellwig Fixes: 76d8137a3113 ("blk-merge: recaculate segment if it isn't less than max segments") Signed-off-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Yufen Yu Reviewed-by: zhengbin Signed-off-by: Yang Yingliang --- block/blk-merge.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 2776ee6c5c3d..7efa8c3e2b72 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -309,13 +309,7 @@ void blk_recalc_rq_segments(struct request *rq) void blk_recount_segments(struct request_queue *q, struct bio *bio) { - 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; + unsigned short seg_cnt = bio_segments(bio); if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && (seg_cnt < queue_max_segments(q))) -- GitLab