gfs2_lookupi() can return NULL if the path to the root is broken by
another rename/rmdir. In this case gfs2_ok_to_move() must check for
this NULL pointer and return error.
Resolves: rhbz#1060246 Signed-off-by: Abhi Das <adas@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>