NFSD: Use unsigned length argument for decode_pathname

Clean up: path name lengths are unsigned on the wire, negative lengths
are not meaningful natively either.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Acked-By: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfsxdr.c

@@ -78,10 +78,10 @@ decode_filename(__be32 *p, char **namp, unsigned int *lenp)
 }
 
 static __be32 *
-decode_pathname(__be32 *p, char **namp, int *lenp)
+decode_pathname(__be32 *p, char **namp, unsigned int *lenp)
 {
 	char		*name;
-	int		i;
+	unsigned int	i;
 
 	if ((p = xdr_decode_string_inplace(p, namp, lenp, NFS_MAXPATHLEN)) != NULL) {
 		for (i = 0, name = *namp; i < *lenp; i++, name++) {