incorrect exit code with truncated backup

I looked into using mylvmbackup and wile doing some tests ran across some issues:

1) abnormal tar exit codes are note detected.
2) snapshot state not checked for validity on exit (ie it's full)
3) snapshot mounted "rw"; this will only cause problems

So basically there are sequences of events that will lead to a silent failure. For production usage this can lead to serious problems.

tar: Error exit delayed from previous errors
 23.0%
20110219 17:56:01 Info: DONE: create tar archive
20110219 17:56:01 Info: Cleaning up...
20110219 17:56:01 Info: Running: umount /var/tmp/mylvmbackup/mnt/backup
20110219 17:56:01 Info: DONE: Unmounting /var/tmp/mylvmbackup/mnt/backup
  /dev/VolGroup90/snap: read failed after 0 of 4096 at 0: Input/output error
20110219 17:56:02 Info: LVM Usage stats:
20110219 17:56:02 Info: LV VG Attr LSize Origin Snap% Move Log Copy% Convert
20110219 17:56:02 Info: snap VolGroup90 Swi-I- 64.00M LogVol90 100.00
20110219 17:56:02 Info: Running: lvremove -f /dev/VolGroup90/snap
  /dev/VolGroup90/snap: read failed after 0 of 4096 at 0: Input/output error
  Logical volume "snap" successfully removed
20110219 17:56:08 Info: DONE: Removing snapshot

exit code = 0