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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 0788EC43381 for ; Thu, 7 Jan 2021 21:47:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFE7D23600 for ; Thu, 7 Jan 2021 21:47:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727881AbhAGVrU (ORCPT ); Thu, 7 Jan 2021 16:47:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:36892 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726386AbhAGVrU (ORCPT ); Thu, 7 Jan 2021 16:47:20 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 141AF23600; Thu, 7 Jan 2021 21:46:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610055999; bh=WqYF7Pa6ZpVpCcZ2vNf1J8/EbxAxiMgwAPAYvp5dLDQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Lk57fWw0z79gwMhVOUES/eP86vzr3eoEI13JEHAquGPwFwas2W3siRt/t7UyvBoKk 0tZgiXCWpFwJhLr8shFHtvIqoKowelEXDPU6e0dZ6R1u6ARcYKOd9SNWV9g3kC5htf kyd9Hg9s3MnfzNZLAPo/fjFL1flAqcHiWzExB12FMq2kEedFYf8VvL20nn1L41t2fi pHB2i4b1dJjDkZi0tEzeZKHGdToii/3IgBBrQDDmNIiKyk9yQFabb9H0Q/rRBcRv5O UlxdU6I6DRf3tz3BpUzWboGLL0apdDkKuPASRbGjC7Aiv4eZLnpw459FLvyces5yDO cQ0QFegKNrszQ== Date: Thu, 7 Jan 2021 13:46:37 -0800 From: Eric Biggers To: Jan Kara Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, Theodore Ts'o , Christoph Hellwig , stable@vger.kernel.org Subject: Re: [PATCH 01/13] fs: avoid double-writing inodes on lazytime expiration Message-ID: References: <20210105005452.92521-1-ebiggers@kernel.org> <20210105005452.92521-2-ebiggers@kernel.org> <20210107144709.GG12990@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210107144709.GG12990@quack2.suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Jan 07, 2021 at 03:47:09PM +0100, Jan Kara wrote: > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > > index acfb55834af23..081e335cdee47 100644 > > --- a/fs/fs-writeback.c > > +++ b/fs/fs-writeback.c > > @@ -1509,11 +1509,22 @@ __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); > > /* Don't write the inode if only I_DIRTY_PAGES was set */ > > if (dirty & ~I_DIRTY_PAGES) { > > - int err = write_inode(inode, wbc); > > + int err; > > + > > + /* > > + * If the inode is being written due to a lazytime timestamp > > + * expiration, then the filesystem needs to be notified about it > > + * so that e.g. the filesystem can update on-disk fields and > > + * journal the timestamp update. Just calling write_inode() > > + * isn't enough. Don't call mark_inode_dirty_sync(), as that > > + * would put the inode back on the dirty list. > > + */ > > + if ((dirty & I_DIRTY_TIME) && inode->i_sb->s_op->dirty_inode) > > + inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_SYNC); > > + > > + err = write_inode(inode, wbc); > > if (ret == 0) > > ret = err; > > } > > I have to say I dislike this special call of ->dirty_inode(). It works but > it makes me wonder, didn't we forget about something or won't we forget in > the future? Because it's very easy to miss this special case... > > I think attached patch (compile-tested only) should actually fix the > problem as well without this special ->dirty_inode() call. It basically > only moves the mark_inode_dirty_sync() before inode->i_state clearing. > Because conceptually mark_inode_dirty_sync() is IMO the right function to > call. It will take care of clearing I_DIRTY_TIME flag (because we are > setting I_DIRTY_SYNC), it will also not touch inode->i_io_list if the inode > is queued for sync (I_SYNC_QUEUED is set in that case). The only problem > with calling it was that it was called *after* clearing dirty bits from > i_state... What do you think? > > Honza > -- > Jan Kara > SUSE Labs, CR > From 80ccc6a78d1c0532f600b98884f7a64e58333485 Mon Sep 17 00:00:00 2001 > From: Jan Kara > Date: Thu, 7 Jan 2021 15:36:05 +0100 > Subject: [PATCH] fs: Make sure inode is clean after __writeback_single_inode() > > Signed-off-by: Jan Kara > --- > fs/fs-writeback.c | 23 ++++++++++++----------- > 1 file changed, 12 insertions(+), 11 deletions(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index acfb55834af2..b9356f470fae 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -1473,22 +1473,25 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) > ret = err; > } > > + /* > + * If inode has dirty timestamps and we need to write them, call > + * mark_inode_dirty_sync() to notify filesystem about it. > + */ > + if (inode->i_state & I_DIRTY_TIME && > + (wbc->for_sync || wbc->sync_mode == WB_SYNC_ALL || > + time_after(jiffies, inode->dirtied_time_when + > + dirtytime_expire_interval * HZ))) { > + trace_writeback_lazytime(inode); > + mark_inode_dirty_sync(inode); > + } > + > /* > * Some filesystems may redirty the inode during the writeback > * due to delalloc, clear dirty metadata flags right before > * write_inode() > */ > spin_lock(&inode->i_lock); > - > dirty = inode->i_state & I_DIRTY; > - if ((inode->i_state & I_DIRTY_TIME) && > - ((dirty & I_DIRTY_INODE) || > - wbc->sync_mode == WB_SYNC_ALL || wbc->for_sync || > - time_after(jiffies, inode->dirtied_time_when + > - dirtytime_expire_interval * HZ))) { > - dirty |= I_DIRTY_TIME; > - trace_writeback_lazytime(inode); > - } > inode->i_state &= ~dirty; > > /* > @@ -1509,8 +1512,6 @@ __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); > /* Don't write the inode if only I_DIRTY_PAGES was set */ > if (dirty & ~I_DIRTY_PAGES) { > int err = write_inode(inode, wbc); It looks like that's going to work, and it fixes the XFS bug too. Note that if __writeback_single_inode() is called from writeback_single_inode() (rather than writeback_sb_inodes()), then the inode might not be queued for sync, in which case mark_inode_dirty_sync() will move it to a writeback list. That's okay because afterwards, writeback_single_inode() will delete the inode from any writeback list if it's been fully cleaned, right? So clean inodes won't get left on a writeback list. It's confusing because there are comments in writeback_single_inode() and above __writeback_single_inode() that say that the inode must not be moved between writeback lists. I take it that those comments are outdated, as they predate I_SYNC_QUEUED being introduced by commit 5afced3bf281 ("writeback: Avoid skipping inode writeback")? - Eric