From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2130.oracle.com ([156.151.31.86]:53855 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758161AbdLSDtQ (ORCPT ); Mon, 18 Dec 2017 22:49:16 -0500 Date: Mon, 18 Dec 2017 19:49:11 -0800 From: "Darrick J. Wong" Subject: Re: [PATCH 3/4] xfs: remove leftover CoW reservations when remounting ro Message-ID: <20171219034911.GB11975@magnolia> References: <151335786780.26575.15542999972223359181.stgit@magnolia> <151335789173.26575.16460983789473064032.stgit@magnolia> <20171219001755.GJ4094@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171219001755.GJ4094@dastard> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner Cc: linux-xfs@vger.kernel.org On Tue, Dec 19, 2017 at 11:17:55AM +1100, Dave Chinner wrote: > On Fri, Dec 15, 2017 at 09:11:31AM -0800, Darrick J. Wong wrote: > > From: Darrick J. Wong > > > > When we're remounting the filesystem readonly, remove all CoW > > preallocations prior to going ro. If the fs goes down after the ro > > remount, we never clean up the staging extents, which means xfs_check > > will trip over them on a subsequent run. Practically speaking, the > > next mount will clean them up too, so this is unlikely to be seen. > > > > Found by adding clonerange to fsstress and running xfs/017. > > > > Signed-off-by: Darrick J. Wong > > --- > > fs/xfs/xfs_super.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c > > index f663022..7b6d150 100644 > > --- a/fs/xfs/xfs_super.c > > +++ b/fs/xfs/xfs_super.c > > @@ -1369,6 +1369,14 @@ xfs_fs_remount( > > > > /* rw -> ro */ > > if (!(mp->m_flags & XFS_MOUNT_RDONLY) && (*flags & MS_RDONLY)) { > > + /* Get rid of any leftover CoW reservations... */ > > + cancel_delayed_work_sync(&mp->m_cowblocks_work); > > + error = xfs_icache_free_cowblocks(mp, NULL); > > + if (error) { > > + xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE); > > + return error; > > + } > > On rw->ro do we start the m_cowblocks_work back up? Assuming you meant to ask about ro->rw, then yes it should get started back up the next time something sets the cowblocks tag. I'm not opposed to starting it back up directly from the ro->rw handler. > What about when we freeze the filesystem - shouldn't we clean > up the cow blocks there, too? We've tried hard in the past to make > freeze and rw->ro exactly the same so that if the system is powered > down while frozen it comes up almost entirely clean just like a > ro-remount in shutdown.... I don't see a hard requirement to clean them up at freeze time, though we certainly can do it for consistency's sake. > And, FWIW, this makes ro->rw and thaw essentially the same, too. Noted. > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com