From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by kanga.kvack.org (Postfix) with ESMTP id 3F8B36B028D for ; Thu, 15 Nov 2018 03:58:15 -0500 (EST) Received: by mail-qk1-f199.google.com with SMTP id 92so43695894qkx.19 for ; Thu, 15 Nov 2018 00:58:15 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id p93si12041096qtd.400.2018.11.15.00.58.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Nov 2018 00:58:14 -0800 (PST) From: Ming Lei Subject: [PATCH V10 17/19] block: don't use bio->bi_vcnt to figure out segment number Date: Thu, 15 Nov 2018 16:53:04 +0800 Message-Id: <20181115085306.9910-18-ming.lei@redhat.com> In-Reply-To: <20181115085306.9910-1-ming.lei@redhat.com> References: <20181115085306.9910-1-ming.lei@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ming Lei , Dave Chinner , Kent Overstreet , Mike Snitzer , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, Shaohua Li , linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , Theodore Ts'o , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com 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@redhat.com Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org Cc: Shaohua Li Cc: linux-raid@vger.kernel.org Cc: linux-erofs@lists.ozlabs.org Cc: David Sterba Cc: linux-btrfs@vger.kernel.org Cc: Darrick J. Wong Cc: linux-xfs@vger.kernel.org Cc: Gao Xiang Cc: Christoph Hellwig Cc: Theodore Ts'o Cc: linux-ext4@vger.kernel.org Cc: Coly Li Cc: linux-bcache@vger.kernel.org Cc: Boaz Harrosh Cc: Bob Peterson Cc: cluster-devel@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