NFS_sattr_sz
p = xdr_reserve_space(xdr, NFS_sattr_sz << 2);
#define NFS_sattrargs_sz (NFS_fhandle_sz+NFS_sattr_sz)
#define NFS_createargs_sz (NFS_diropargs_sz+NFS_sattr_sz)
#define NFS_symlinkargs_sz (NFS_diropargs_sz+1+NFS_sattr_sz)