Hi Andrew,
The xfs_repair output is valid. All the inodes that are reporting errors
are orphaned inodes that were moved into lost+found. At the start of
phase 4, the lost+found directory is deleted which causes all the inodes
in lost+found to be re-orphaned. The current solution to this problem is
to rename lost+found after an xfs_repair run and then unmount and try
xfs_repair again.
Regarding the shutdown, that is not normal and I personally don't know
what the problem is from the trace. If it's a corrupt lost+found that
xfs_repair is generating (I gather you are rm'ing lost+found), the
second xfs_repair run after a rename should identify the problem with
the directory. You can also try running xfs_check on the device as it
may pick up something xfs_repair is missing.
Regards,
Barry.