generic: shutdown fs after log recovery

generic: shutdown fs after log recovery

XFS had a bug that lead to a possible out-of-order log recovery
situation (e.g., replay a stale modification from the log over more
recent metadata in destination buffer). This resulted in false
corruption reports during log recovery and thus mount failure.

This condition is caused by system crash or filesystem shutdown
shortly after a successful log recovery. Add a test to run a
combined workload, fs shutdown and log recovery loop known to
reproduce the problem on affected kernels.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>