xfs: write unmount record for ro mounts
authorEric Sandeen <sandeen@sandeen.net>
Wed, 9 Aug 2017 01:19:47 +0000 (18:19 -0700)
committerDarrick J. Wong <darrick.wong@oracle.com>
Tue, 22 Aug 2017 16:22:23 +0000 (09:22 -0700)
commit757a69ef6cf2bf839bd4088e5609ddddd663b0c4
tree801c716342adc835f8400b3b057f02124b12bea6
parent6470812e22261d2342ef1597be62e63a0423d691
xfs: write unmount record for ro mounts

There are dueling comments in the xfs code about intent
for log writes when unmounting a readonly filesystem.

In xfs_mountfs, we see the intent:

/*
 * Now the log is fully replayed, we can transition to full read-only
 * mode for read-only mounts. This will sync all the metadata and clean
 * the log so that the recovery we just performed does not have to be
 * replayed again on the next mount.
 */

and it calls xfs_quiesce_attr(), but by the time we get to
xfs_log_unmount_write(), it returns early for a RDONLY mount:

 * Don't write out unmount record on read-only mounts.

Because of this, sequential ro mounts of a filesystem with
a dirty log will replay the log each time, which seems odd.

Fix this by writing an unmount record even for RO mounts, as long
as norecovery wasn't specified (don't write a clean log record
if a dirty log may still be there!) and the log device is
writable.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
fs/xfs/xfs_log.c