From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Date: Thu, 15 Nov 2018 16:53:04 +0800 Subject: [Cluster-devel] [PATCH V10 17/19] block: don't use bio->bi_vcnt to figure out segment number In-Reply-To: <20181115085306.9910-1-ming.lei@redhat.com> References: <20181115085306.9910-1-ming.lei@redhat.com> Message-ID: <20181115085306.9910-18-ming.lei@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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"). Cc: Dave Chinner Cc: Kent Overstreet Fixes: 7f60dcaaf91 ("block: blk-merge: fix blk_recount_segments()") Cc: Mike Snitzer Cc: dm-devel at redhat.com Cc: Alexander Viro Cc: linux-fsdevel at vger.kernel.org Cc: Shaohua Li Cc: linux-raid at vger.kernel.org Cc: linux-erofs at lists.ozlabs.org Cc: David Sterba Cc: linux-btrfs at vger.kernel.org Cc: Darrick J. Wong Cc: linux-xfs at vger.kernel.org Cc: Gao Xiang Cc: Christoph Hellwig Cc: Theodore Ts'o Cc: linux-ext4 at vger.kernel.org Cc: Coly Li Cc: linux-bcache at vger.kernel.org Cc: Boaz Harrosh Cc: Bob Peterson Cc: cluster-devel at redhat.com Signed-off-by: Ming Lei --- 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 cb9f49bcfd36..153a659fde74 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -429,13 +429,7 @@ 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))) -- 2.9.5