semantics.

SGI-PV: 954580
SGI-Modid: xfs-linux-melb:xfs-kern:26563a
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NNathan Scott <nathans@sgi.com>
Signed-off-by: NTim Shimmin <tes@sgi.com>