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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 396E4C2BB1D for ; Wed, 11 Mar 2020 23:54:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49A67206B1 for ; Wed, 11 Mar 2020 23:54:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731525AbgCKXyP (ORCPT ); Wed, 11 Mar 2020 19:54:15 -0400 Received: from mail105.syd.optusnet.com.au ([211.29.132.249]:60067 "EHLO mail105.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731399AbgCKXyP (ORCPT ); Wed, 11 Mar 2020 19:54:15 -0400 Received: from dread.disaster.area (pa49-195-202-68.pa.nsw.optusnet.com.au [49.195.202.68]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 6FB1C3A2B28; Thu, 12 Mar 2020 10:54:10 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1jCBAu-0005Ez-JZ; Thu, 12 Mar 2020 10:54:08 +1100 Date: Thu, 12 Mar 2020 10:54:08 +1100 From: Dave Chinner To: Eric Biggers Cc: Theodore Ts'o , Linux Filesystem Development List , Ext4 Developers List , linux-f2fs-devel@lists.sourceforge.net Subject: Re: [PATCH] writeback: avoid double-writing the inode on a lazytime expiration Message-ID: <20200311235408.GX10737@dread.disaster.area> References: <20200306004555.GB225345@gmail.com> <20200307020043.60118-1-tytso@mit.edu> <20200311032009.GC46757@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200311032009.GC46757@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=X6os11be c=1 sm=1 tr=0 a=mqTaRPt+QsUAtUurwE173Q==:117 a=mqTaRPt+QsUAtUurwE173Q==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=SS2py6AdgQ4A:10 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=7-415B0cAAAA:8 a=tSSHeJGq2Hsi8ItP-fQA:9 a=CjuIK1q_8ugA:10 a=AjGcO6oz07-iQ99wixmX:22 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Mar 10, 2020 at 08:20:09PM -0700, Eric Biggers wrote: > On Fri, Mar 06, 2020 at 09:00:43PM -0500, Theodore Ts'o wrote: > > In the case that an inode has dirty timestamp for longer than the > > lazytime expiration timeout (or if all such inodes are being flushed > > out due to a sync or syncfs system call), we need to inform the file > > system that the inode is dirty so that the inode's timestamps can be > > copied out to the on-disk data structures. That's because if the file > > system supports lazytime, it will have ignored the dirty_inode(inode, > > I_DIRTY_TIME) notification when the timestamp was modified in memory.q > > > > Previously, this was accomplished by calling mark_inode_dirty_sync(), > > but that has the unfortunate side effect of also putting the inode the > > writeback list, and that's not necessary in this case, since we will > > immediately call write_inode() afterwards. > > > > Eric Biggers noticed that this was causing problems for fscrypt after > > the key was removed[1]. > > > > [1] https://lore.kernel.org/r/20200306004555.GB225345@gmail.com > > > > Reported-by: Eric Biggers > > Signed-off-by: Theodore Ts'o > > --- > > fs/fs-writeback.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > > index 76ac9c7d32ec..32101349ba97 100644 > > --- a/fs/fs-writeback.c > > +++ b/fs/fs-writeback.c > > @@ -1504,8 +1504,9 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) > > > > spin_unlock(&inode->i_lock); > > > > - if (dirty & I_DIRTY_TIME) > > - mark_inode_dirty_sync(inode); > > + /* This was a lazytime expiration; we need to tell the file system */ > > + if (dirty & I_DIRTY_TIME_EXPIRED && inode->i_sb->s_op->dirty_inode) > > + inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_TIME_EXPIRED); > > /* Don't write the inode if only I_DIRTY_PAGES was set */ > > if (dirty & ~I_DIRTY_PAGES) { > > int err = write_inode(inode, wbc); > > -- > > Thanks Ted! This fixes the fscrypt test failure. > > However, are you sure this works correctly on all filesystems? I'm not sure > about XFS. XFS only implements ->dirty_inode(), not ->write_inode(), and in its > ->dirty_inode() it does: > > static void > xfs_fs_dirty_inode( > struct inode *inode, > int flag) > { > struct xfs_inode *ip = XFS_I(inode); > struct xfs_mount *mp = ip->i_mount; > struct xfs_trans *tp; > > if (!(inode->i_sb->s_flags & SB_LAZYTIME)) > return; > if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME)) > return; > > if (xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp)) > return; > xfs_ilock(ip, XFS_ILOCK_EXCL); > xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL); > xfs_trans_log_inode(tp, ip, XFS_ILOG_TIMESTAMP); > xfs_trans_commit(tp); > } > > > So flag=I_DIRTY_TIME_EXPIRED will be a no-op. > > Maybe you should be using I_DIRTY_SYNC instead? Or perhaps XFS should be > checking for either I_DIRTY_TIME_EXPIRED or I_DIRTY_SYNC? Right, XFS does not use the VFS inode writeback code at all - we track all metadata changes internally via journalling. The VFS uses I_DIRTY_SYNC to indicate and inode is metadata dirty and a writeback candidate. Hence if we need to mark an inode dirty for integrity purposes for _any reason_, then I_DIRTY_SYNC is the correct flag to be passing to ->dirty_inode. Cheers, Dave. -- Dave Chinner david@fromorbit.com 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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 4472BC0044D for ; Wed, 11 Mar 2020 23:54:25 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 40B29206BE; Wed, 11 Mar 2020 23:54:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sourceforge.net header.i=@sourceforge.net header.b="cjLM+6rn"; 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Wed, 11 Mar 2020 23:54:20 +0000 Received: from dread.disaster.area (pa49-195-202-68.pa.nsw.optusnet.com.au [49.195.202.68]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 6FB1C3A2B28; Thu, 12 Mar 2020 10:54:10 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1jCBAu-0005Ez-JZ; Thu, 12 Mar 2020 10:54:08 +1100 Date: Thu, 12 Mar 2020 10:54:08 +1100 From: Dave Chinner To: Eric Biggers Message-ID: <20200311235408.GX10737@dread.disaster.area> References: <20200306004555.GB225345@gmail.com> <20200307020043.60118-1-tytso@mit.edu> <20200311032009.GC46757@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200311032009.GC46757@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=X6os11be c=1 sm=1 tr=0 a=mqTaRPt+QsUAtUurwE173Q==:117 a=mqTaRPt+QsUAtUurwE173Q==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=SS2py6AdgQ4A:10 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=7-415B0cAAAA:8 a=tSSHeJGq2Hsi8ItP-fQA:9 a=CjuIK1q_8ugA:10 a=AjGcO6oz07-iQ99wixmX:22 a=biEYGPWJfzWAr4FL6Ov7:22 X-Headers-End: 1jCBB4-0056wS-MV Subject: Re: [f2fs-dev] [PATCH] writeback: avoid double-writing the inode on a lazytime expiration X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linux Filesystem Development List , Ext4 Developers List , Theodore Ts'o , linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Tue, Mar 10, 2020 at 08:20:09PM -0700, Eric Biggers wrote: > On Fri, Mar 06, 2020 at 09:00:43PM -0500, Theodore Ts'o wrote: > > In the case that an inode has dirty timestamp for longer than the > > lazytime expiration timeout (or if all such inodes are being flushed > > out due to a sync or syncfs system call), we need to inform the file > > system that the inode is dirty so that the inode's timestamps can be > > copied out to the on-disk data structures. That's because if the file > > system supports lazytime, it will have ignored the dirty_inode(inode, > > I_DIRTY_TIME) notification when the timestamp was modified in memory.q > > > > Previously, this was accomplished by calling mark_inode_dirty_sync(), > > but that has the unfortunate side effect of also putting the inode the > > writeback list, and that's not necessary in this case, since we will > > immediately call write_inode() afterwards. > > > > Eric Biggers noticed that this was causing problems for fscrypt after > > the key was removed[1]. > > > > [1] https://lore.kernel.org/r/20200306004555.GB225345@gmail.com > > > > Reported-by: Eric Biggers > > Signed-off-by: Theodore Ts'o > > --- > > fs/fs-writeback.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > > index 76ac9c7d32ec..32101349ba97 100644 > > --- a/fs/fs-writeback.c > > +++ b/fs/fs-writeback.c > > @@ -1504,8 +1504,9 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) > > > > spin_unlock(&inode->i_lock); > > > > - if (dirty & I_DIRTY_TIME) > > - mark_inode_dirty_sync(inode); > > + /* This was a lazytime expiration; we need to tell the file system */ > > + if (dirty & I_DIRTY_TIME_EXPIRED && inode->i_sb->s_op->dirty_inode) > > + inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_TIME_EXPIRED); > > /* Don't write the inode if only I_DIRTY_PAGES was set */ > > if (dirty & ~I_DIRTY_PAGES) { > > int err = write_inode(inode, wbc); > > -- > > Thanks Ted! This fixes the fscrypt test failure. > > However, are you sure this works correctly on all filesystems? I'm not sure > about XFS. XFS only implements ->dirty_inode(), not ->write_inode(), and in its > ->dirty_inode() it does: > > static void > xfs_fs_dirty_inode( > struct inode *inode, > int flag) > { > struct xfs_inode *ip = XFS_I(inode); > struct xfs_mount *mp = ip->i_mount; > struct xfs_trans *tp; > > if (!(inode->i_sb->s_flags & SB_LAZYTIME)) > return; > if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME)) > return; > > if (xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp)) > return; > xfs_ilock(ip, XFS_ILOCK_EXCL); > xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL); > xfs_trans_log_inode(tp, ip, XFS_ILOG_TIMESTAMP); > xfs_trans_commit(tp); > } > > > So flag=I_DIRTY_TIME_EXPIRED will be a no-op. > > Maybe you should be using I_DIRTY_SYNC instead? Or perhaps XFS should be > checking for either I_DIRTY_TIME_EXPIRED or I_DIRTY_SYNC? Right, XFS does not use the VFS inode writeback code at all - we track all metadata changes internally via journalling. The VFS uses I_DIRTY_SYNC to indicate and inode is metadata dirty and a writeback candidate. Hence if we need to mark an inode dirty for integrity purposes for _any reason_, then I_DIRTY_SYNC is the correct flag to be passing to ->dirty_inode. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel