Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:57070 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726053AbeKZNKw (ORCPT ); Mon, 26 Nov 2018 08:10:52 -0500 From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Theodore Ts'o , Omar Sandoval , Sagi Grimberg , Dave Chinner , Kent Overstreet , Mike Snitzer , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, Shaohua Li , linux-raid@vger.kernel.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com, Ming Lei Subject: [PATCH V12 04/20] block: don't use bio->bi_vcnt to figure out segment number Date: Mon, 26 Nov 2018 10:17:04 +0800 Message-Id: <20181126021720.19471-5-ming.lei@redhat.com> In-Reply-To: <20181126021720.19471-1-ming.lei@redhat.com> References: <20181126021720.19471-1-ming.lei@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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: Christoph Hellwig Fixes: 76d8137a3113 ("blk-merge: recaculate segment if it isn't less than max segments") 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 e69d8f8ba819..51ec6ca56a0a 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -367,13 +367,7 @@ 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