Skip check for mandatory locks when unlocking

Skip check for mandatory locks when unlocking

commit ee860b6a650360c91f5d5f9a94262aad9be90015 upstream.

ocfs2_lock() will skip locks on file which has mode set to 02666. This
is a problem in cases where the mode of the file is changed after a
process has obtained a lock on the file.

ocfs2_lock() should skip the check for mandatory locks when unlocking a
file.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>