From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by kanga.kvack.org (Postfix) with ESMTP id 108226B09B8 for ; Fri, 16 Nov 2018 08:55:14 -0500 (EST) Received: by mail-wr1-f70.google.com with SMTP id g17-v6so26477649wrw.6 for ; Fri, 16 Nov 2018 05:55:14 -0800 (PST) Received: from newverein.lst.de (verein.lst.de. [213.95.11.211]) by mx.google.com with ESMTPS id u14-v6si24364365wrq.254.2018.11.16.05.55.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Nov 2018 05:55:12 -0800 (PST) Date: Fri, 16 Nov 2018 14:55:12 +0100 From: Christoph Hellwig Subject: Re: [PATCH V10 17/19] block: don't use bio->bi_vcnt to figure out segment number Message-ID: <20181116135512.GM3165@lst.de> References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-18-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181115085306.9910-18-ming.lei@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, 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 On Thu, Nov 15, 2018 at 04:53:04PM +0800, Ming Lei wrote: > 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"). Looks good, but shouldn't this go to the beginning of the series? Reviewed-by: Christoph Hellwig