Busy-file renames don't actually work across directories, so we need
to limit this code to renames within the same dir.

This fixes the bug detailed here:

    https://bugzilla.redhat.com/show_bug.cgi?id=591938Signed-off-by: NJeff Layton <jlayton@redhat.com>
CC: Stable <stable@kernel.org>
Signed-off-by: NSteve French <sfrench@us.ibm.com>