Snapshot hook should parse fsck exit status

[ewxrjk]

> rsbackup-snapshot-hook
WARNING: backup of araminta:home to backup5: preBackup: exited with status 1
HOOK: EXEC: umount /snap/home
umount: /snap/home: not mounted
HOOK: EXEC: lvremove --force /dev/mapper/amfast-home.snap
  Logical volume "home.snap" successfully removed
HOOK: EXEC: lvcreate --extents 4710 --name home.snap --snapshot /dev/amfast/home
  Logical volume "home.snap" created
HOOK: EXEC: fsck -a /dev/mapper/amfast-home.snap
fsck from util-linux 2.20.1
/dev/mapper/amfast-home.snap: Clearing orphaned inode 2754454 (uid=1000, gid=100
0, mode=0100644, size=22523)
/dev/mapper/amfast-home.snap: Clearing orphaned inode 2754442 (uid=1000, gid=100
0, mode=0100644, size=22523)
/dev/mapper/amfast-home.snap: Clearing orphaned inode 2754438 (uid=1000, gid=100
0, mode=0100644, size=22523)
/dev/mapper/amfast-home.snap has been mounted 24 times without being checked, ch
eck forced.
/dev/mapper/amfast-home.snap: 609974/6029312 files (0.6% non-contiguous), 796033
3/24117248 blocks
HOOK: EXEC: umount /snap/home
umount: /snap/home: not mounted

The reason is that fsck exits nonzero if errors are corrected (see man page). An exit status of 1 shouldn't be considered fatal (at least with Linux's fsck, but this script uses Linux's LVM...).

Workaround that doesn't involve unmounting: disable snapshots for affected filesystems.