store 128 bytes, usually NFS servers don't use file handles that
   are more than 32 bytes in size.  This patch creates an efficient
   mechanism for comparing file handles that ignores the unused bytes
   in a file handle.
Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@fys.uio.no>