xfs: stress test cycling parent pointers with online repair

xfs: stress test cycling parent pointers with online repair

Add a couple of new tests to exercise directory and parent pointer
repair against rename() calls moving child subdirectories from one
parent to another.  This is a useful test because it turns out that the
VFS doesn't lock the child subdirectory (it does lock the parents), so
repair must be more careful.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>