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=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 01EB8C433DF for ; Tue, 25 Aug 2020 06:22:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF4C5207FB for ; Tue, 25 Aug 2020 06:22:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="q+m2Hw1S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728845AbgHYGWp (ORCPT ); Tue, 25 Aug 2020 02:22:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725946AbgHYGWo (ORCPT ); Tue, 25 Aug 2020 02:22:44 -0400 Received: from mail-il1-x143.google.com (mail-il1-x143.google.com [IPv6:2607:f8b0:4864:20::143]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5BF9C061574; Mon, 24 Aug 2020 23:22:44 -0700 (PDT) Received: by mail-il1-x143.google.com with SMTP id k4so9451129ilr.12; Mon, 24 Aug 2020 23:22:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=nJnF6NzmSch03bI5+ZVNRt+pUANjQezLXGWDqR64ZyE=; b=q+m2Hw1SeiQXjmCeL5sOpmQ/Q7e7rxTjM9Crx/jDVjVDNid8RGwY33P8onK0iNDsnX neuwYqxm2KrM/aBS0s91yNN/YO86OAaA8/dtY2Mq4Wp0y3bv62ipQH9IKOKmps3C3K74 z7qvnaQaLqYPg1hdb8aAdoSw53YI66Ixvrxf3TWgzNiL9xmoOHKTZxiS10D+oz0WppPB vzMVfTV7+HNlMrAZdu4P0SyXScJdKuCYsgkrBdQyOESpxpmcZDLtiskzzt56UPoNfEXI FfDdvPSoDnjiF8Dz/xxGoJXTPFVoTKXmqesRBj0WDx1hyL8DYn5wabA8IP9KLXLRI9OL uPig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=nJnF6NzmSch03bI5+ZVNRt+pUANjQezLXGWDqR64ZyE=; b=kFwuQznf29BTHeLvXDK4ilG1TCOr6sNR5PhvniLxeCsPpF7LlQNm/jrMrhM1kAFYfl isTuZKoJAZ8mmfvYaar5y08MC7MwAHbA2+FRa1i50Yl07k8t6h5WumPd4Lyv3pnw/AtR SICvafoV8QF6lJp78hsijGFinsSXhSizfPnsbxuSrT1BjtR+H9VZSi7IFbs4e7sChuXR 4R1+wPSSShf2QvPQT75GjMU9Oj/HzaChJWDlJwn5l7mjzy5wQe9xlsmPQJGrRkpAKPPI 5JpUM4THVXTxoG+VV2G+vfNd1duEQLJjQRYhnm0cgbTAXvPWgRqe5wHZQhzpTFgPXUbK 9Mog== X-Gm-Message-State: AOAM530MpQycEZKw06Hlg/brkaUBk1DsvH5/2/WyjdCQsvyIEtPXaVDj Ol2aJZzy23050B0WC2kcrzOETS4El8hvvsatDsM= X-Google-Smtp-Source: ABdhPJzQfbaRyHzQbR9fyU0qXLrO4Y2S+GlY4XMCXjt/Xr0ZQ+i+TOlj55R6o1mM/ROaK6ZHgSzas1SCwe69FKAmeqk= X-Received: by 2002:a92:9f57:: with SMTP id u84mr8100793ili.203.1598336564033; Mon, 24 Aug 2020 23:22:44 -0700 (PDT) MIME-Version: 1.0 References: <20200824014234.7109-1-laoar.shao@gmail.com> <20200824014234.7109-3-laoar.shao@gmail.com> <20200824130925.a3d2d2b75ac3a6b4eba72fb9@linux-foundation.org> <20200824205647.GG17456@casper.infradead.org> <20200825053233.GN12131@dread.disaster.area> In-Reply-To: <20200825053233.GN12131@dread.disaster.area> From: Yafang Shao Date: Tue, 25 Aug 2020 14:22:08 +0800 Message-ID: Subject: Re: [PATCH v6 2/2] xfs: avoid transaction reservation recursion To: Dave Chinner Cc: Matthew Wilcox , Andrew Morton , Christoph Hellwig , "Darrick J. Wong" , Michal Hocko , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Linux MM Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Aug 25, 2020 at 1:32 PM Dave Chinner wrote: > > On Mon, Aug 24, 2020 at 09:56:47PM +0100, Matthew Wilcox wrote: > > On Mon, Aug 24, 2020 at 01:09:25PM -0700, Andrew Morton wrote: > > > On Mon, 24 Aug 2020 09:42:34 +0800 Yafang Shao wrote: > > > > > > > --- a/include/linux/iomap.h > > > > +++ b/include/linux/iomap.h > > > > @@ -271,4 +271,11 @@ int iomap_swapfile_activate(struct swap_info_struct *sis, > > > > # define iomap_swapfile_activate(sis, swapfile, pagespan, ops) (-EIO) > > > > #endif /* CONFIG_SWAP */ > > > > > > > > +/* Use the journal_info to indicate current is in a transaction */ > > > > +static inline bool > > > > +fstrans_context_active(void) > > > > +{ > > > > + return current->journal_info != NULL; > > > > +} > > > > > > Why choose iomap.h for this? > > > > Because it gets used in iomap/buffered-io.c > > > > I don't think this is necessarily a useful abstraction, to be honest. > > I'd just open-code 'if (current->journal_info)' or !current->journal_info, > > whichever way round the code is: > > > > fs/btrfs/delalloc-space.c: if (current->journal_info) > > fs/ceph/xattr.c: if (current->journal_info) { > > fs/gfs2/bmap.c: if (current->journal_info) { > > fs/jbd2/transaction.c: if (WARN_ON(current->journal_info)) { > > fs/reiserfs/super.c: if (!current->journal_info) { > > /me wonders idly if any of the other filesystems that use > current->journal_info can have an active transaction while calling > ->writepages... > > .... and if so, whether this patchset has taken the wrong path in > trying to use current->journal_info for XFS to re-implement this > warning..... > > .... so we'll have to remove or rework this yet again when other > filesystems are converted to use iomap.... > > /me suspects the btrfs_write_and_wait_transaction() is a path where > this can actually happen... > How about adding a flag in struct writeback_control ? struct writeback_control { ... unsigned fstrans_check:1; /* Whether to check the current is in fstrans */ }; Then we can set it in xfs_vm_writepage(s), for example, xfs_vm_writepage { wbc->fstrans_check = 1; // set it for XFS only. return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops); } And then we check this flag in iomap_do_writepage(): iomap_do_writepage if (WARN_ON_ONCE(wbc->fstrans_check && current->journal_info)) goto redirty; -- Thanks Yafang