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xfs: preserve inode versioning across remounts

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The MS_I_VERSION mount flag is exposed via the VFS, as documented
in the mount manpages etc; see the iversion and noiversion mount
options in mount(8).

As a result, mount -o remount looks for this option in /proc/mounts
and will only send the I_VERSION flag back in during remount it it
is present.  Since it's not there, a remount will /remove/ the
I_VERSION flag at the vfs level, and iversion functionality is lost.

xfs v5 superblocks intend to always have i_version enabled; it is
set as a default at mount time, but is lost during remount for the
reasons above.

The generic fix would be to expose this documented option in
/proc/mounts, but since that was rejected, fix it up again in the
xfs remount path instead, so that at least xfs won't suffer from
this misbehavior.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Eric Sandeen 2020-07-15 08:30:37 -07:00 committed by Darrick J. Wong
parent 8464e650b9
commit 4750a171c3
1 changed files with 4 additions and 0 deletions
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4
fs/xfs/xfs_super.c
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@ -1721,6 +1721,10 @@ xfs_fc_reconfigure(
int flags = fc->sb_flags;
int error;
/* version 5 superblocks always support version counters. */
if (XFS_SB_VERSION_NUM(&mp->m_sb) == XFS_SB_VERSION_5)
fc->sb_flags |= SB_I_VERSION;
error = xfs_fc_validate_params(new_mp);
if (error)
return error;