From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 499DAC43610 for ; Fri, 16 Nov 2018 13:53:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EE482086B for ; Fri, 16 Nov 2018 13:53:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0EE482086B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389616AbeKQAFl (ORCPT ); Fri, 16 Nov 2018 19:05:41 -0500 Received: from verein.lst.de ([213.95.11.211]:50051 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727727AbeKQAFl (ORCPT ); Fri, 16 Nov 2018 19:05:41 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id 7F57068D60; Fri, 16 Nov 2018 14:53:08 +0100 (CET) Date: Fri, 16 Nov 2018 14:53:08 +0100 From: Christoph Hellwig 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 Subject: Re: [PATCH V10 14/19] block: enable multipage bvecs Message-ID: <20181116135308.GK3165@lst.de> References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-15-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181115085306.9910-15-ming.lei@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org > - > - if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) { > - bv->bv_len += len; > - bio->bi_iter.bi_size += len; > - return true; > - } > + struct request_queue *q = NULL; > + > + if (page == bv->bv_page && off == (bv->bv_offset + bv->bv_len) > + && (off + len) <= PAGE_SIZE) How could the page struct be the same, but the range beyond PAGE_SIZE (at least with the existing callers)? Also no need for the inner btraces, and the && always goes on the first line. > + if (bio->bi_disk) > + q = bio->bi_disk->queue; > + > + /* disable multi-page bvec too if cluster isn't enabled */ > + if (!q || !blk_queue_cluster(q) || > + ((page_to_phys(bv->bv_page) + bv->bv_offset + bv->bv_len) != > + (page_to_phys(page) + off))) > + return false; > + merge: > + bv->bv_len += len; > + bio->bi_iter.bi_size += len; > + return true; Ok, this is scary, as it will give differen results depending on when bi_disk is assigned. But then again we shouldn't really do the cluster check here, but rather when splitting the bio for the actual low-level driver. (and eventually we should kill this clustering setting off in favor of our normal segment limits).