Ok, I fixed the few obvious bugs that I left in as an exercise to the
reader and would be ready to commit the result after some more tests
tomorrow.

This does, btw.,  also fix CODA and NTFS on 64bit machines (filehandle was
too large).

While playing wiht this I noticed that we do a *lot* calls to vfs_composefh()
in kernels with NFS server support:

 sys_read -> dofileread -> vn_read -> VOP_LEASE() -> genfs_lease_check()
  -> nqsrv_getlease() -> vfs_composefh()

This sounds pretty expensive, is it a bug, or is it realy needed?

Martin