NFSv4: Add a helper for encoding opaque data

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index af11e8b..de4cb5c 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -885,6 +885,14 @@
 	return p;
 }
 
+static void encode_opaque_fixed(struct xdr_stream *xdr, const void *buf, size_t len)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, len);
+	xdr_encode_opaque_fixed(p, buf, len);
+}
+
 static void encode_string(struct xdr_stream *xdr, unsigned int len, const char *str)
 {
 	__be32 *p;
@@ -922,11 +930,7 @@
 
 static void encode_nfs4_verifier(struct xdr_stream *xdr, const nfs4_verifier *verf)
 {
-	__be32 *p;
-
-	p = xdr_reserve_space(xdr, NFS4_VERIFIER_SIZE);
-	BUG_ON(p == NULL);
-	xdr_encode_opaque_fixed(p, verf->data, NFS4_VERIFIER_SIZE);
+	encode_opaque_fixed(xdr, verf->data, NFS4_VERIFIER_SIZE);
 }
 
 static void encode_attrs(struct xdr_stream *xdr, const struct iattr *iap, const struct nfs_server *server)