[XFS] Keep lockdep happy.

SGI-PV: 956964
SGI-Modid: xfs-linux-melb:xfs-kern:27200a

Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>