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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EAD3C19F2A for ; Sun, 7 Aug 2022 23:08:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231263AbiHGXIT (ORCPT ); Sun, 7 Aug 2022 19:08:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229907AbiHGXIQ (ORCPT ); Sun, 7 Aug 2022 19:08:16 -0400 Received: from mail104.syd.optusnet.com.au (mail104.syd.optusnet.com.au [211.29.132.246]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5DAA33891; Sun, 7 Aug 2022 16:08:15 -0700 (PDT) Received: from dread.disaster.area (pa49-181-193-158.pa.nsw.optusnet.com.au [49.181.193.158]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id E13F762CFE2; Mon, 8 Aug 2022 09:08:11 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1oKpNS-00AQOr-2N; Mon, 08 Aug 2022 09:08:10 +1000 Date: Mon, 8 Aug 2022 09:08:10 +1000 From: Dave Chinner To: Lukas Czerner Cc: linux-ext4@vger.kernel.org, jlayton@kernel.org, tytso@mit.edu, linux-fsdevel@vger.kernel.org, Christoph Hellwig , Jan Kara Subject: Re: [PATCH v2 2/3] fs: record I_DIRTY_TIME even if inode already has I_DIRTY_INODE Message-ID: <20220807230810.GF3861211@dread.disaster.area> References: <20220803105340.17377-1-lczerner@redhat.com> <20220803105340.17377-2-lczerner@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220803105340.17377-2-lczerner@redhat.com> X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.4 cv=e9dl9Yl/ c=1 sm=1 tr=0 ts=62f045dd a=SeswVvpAPK2RnNNwqI8AaA==:117 a=SeswVvpAPK2RnNNwqI8AaA==:17 a=kj9zAlcOel0A:10 a=biHskzXt2R4A:10 a=7-415B0cAAAA:8 a=JfrnYn6hAAAA:8 a=20KFwNOVAAAA:8 a=DIIZEVAEUkBuOxPNP6QA:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 a=1CNFftbPRP8L7MoqJWF3:22 Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed, Aug 03, 2022 at 12:53:39PM +0200, Lukas Czerner wrote: > Currently the I_DIRTY_TIME will never get set if the inode already has > I_DIRTY_INODE with assumption that it supersedes I_DIRTY_TIME. That's > true, however ext4 will only update the on-disk inode in > ->dirty_inode(), not on actual writeback. As a result if the inode > already has I_DIRTY_INODE state by the time we get to > __mark_inode_dirty() only with I_DIRTY_TIME, the time was already filled > into on-disk inode and will not get updated until the next I_DIRTY_INODE > update, which might never come if we crash or get a power failure. > > The problem can be reproduced on ext4 by running xfstest generic/622 > with -o iversion mount option. > > Fix it by allowing I_DIRTY_TIME to be set even if the inode already has > I_DIRTY_INODE. Also make sure that the case is properly handled in > writeback_single_inode() as well. Additionally changes in > xfs_fs_dirty_inode() was made to accommodate for I_DIRTY_TIME in flag. > > Thanks Jan Kara for suggestions on how to make this work properly. > > Cc: Dave Chinner > Cc: Christoph Hellwig > Signed-off-by: Lukas Czerner > Suggested-by: Jan Kara > --- > v2: Reworked according to suggestions from Jan .... > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c > index aa977c7ea370..cff05a4771b5 100644 > --- a/fs/xfs/xfs_super.c > +++ b/fs/xfs/xfs_super.c > @@ -658,7 +658,8 @@ xfs_fs_dirty_inode( > > if (!(inode->i_sb->s_flags & SB_LAZYTIME)) > return; > - if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME)) > + if ((flag & ~I_DIRTY_TIME) != I_DIRTY_SYNC || > + !((inode->i_state | flag) & I_DIRTY_TIME)) > return; My eyes, they bleed. The dirty time code was already a horrid abomination, and this makes it worse. >From looking at the code, I cannot work out what the new semantics for I_DIRTY_TIME and I_DIRTY_SYNC are supposed to be, nor can I work out what the condition this is new code is supposed to be doing. I *can't verify it is correct* by reading the code. Can you please add a comment here explaining the conditions where we don't have to log a new timestamp update? Also, if "flag" now contains multiple flags, can you rename it "flags"? Cheers, Dave. -- Dave Chinner david@fromorbit.com