SUNRPC: New xdr_streams XDR encoder API

Now that all client-side XDR encoder routines use xdr_streams, there
should be no need to support the legacy calling sequence [rpc_rqst *,
__be32 *, RPC arg *] anywhere.  We can construct an xdr_stream in the
generic RPC code, instead of in each encoder function.

Also, all the client-side encoder functions return 0 now, making a
return value superfluous.  Take this opportunity to convert them to
return void instead.

This is a refactoring change.  It should not cause different behavior.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 3835ce3..42b46f9a 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -1231,9 +1231,19 @@
 	return NULL;
 }
 
+static void gss_wrap_req_encode(kxdreproc_t encode, struct rpc_rqst *rqstp,
+				__be32 *p, void *obj)
+{
+	struct xdr_stream xdr;
+
+	xdr_init_encode(&xdr, &rqstp->rq_snd_buf, p);
+	encode(rqstp, &xdr, obj);
+}
+
 static inline int
 gss_wrap_req_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
-		kxdrproc_t encode, struct rpc_rqst *rqstp, __be32 *p, void *obj)
+		   kxdreproc_t encode, struct rpc_rqst *rqstp,
+		   __be32 *p, void *obj)
 {
 	struct xdr_buf	*snd_buf = &rqstp->rq_snd_buf;
 	struct xdr_buf	integ_buf;
@@ -1249,9 +1259,7 @@
 	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
 	*p++ = htonl(rqstp->rq_seqno);
 
-	status = encode(rqstp, p, obj);
-	if (status)
-		return status;
+	gss_wrap_req_encode(encode, rqstp, p, obj);
 
 	if (xdr_buf_subsegment(snd_buf, &integ_buf,
 				offset, snd_buf->len - offset))
@@ -1325,7 +1333,8 @@
 
 static inline int
 gss_wrap_req_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
-		kxdrproc_t encode, struct rpc_rqst *rqstp, __be32 *p, void *obj)
+		  kxdreproc_t encode, struct rpc_rqst *rqstp,
+		  __be32 *p, void *obj)
 {
 	struct xdr_buf	*snd_buf = &rqstp->rq_snd_buf;
 	u32		offset;
@@ -1342,9 +1351,7 @@
 	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
 	*p++ = htonl(rqstp->rq_seqno);
 
-	status = encode(rqstp, p, obj);
-	if (status)
-		return status;
+	gss_wrap_req_encode(encode, rqstp, p, obj);
 
 	status = alloc_enc_pages(rqstp);
 	if (status)
@@ -1394,7 +1401,7 @@
 
 static int
 gss_wrap_req(struct rpc_task *task,
-	     kxdrproc_t encode, void *rqstp, __be32 *p, void *obj)
+	     kxdreproc_t encode, void *rqstp, __be32 *p, void *obj)
 {
 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
 	struct gss_cred	*gss_cred = container_of(cred, struct gss_cred,
@@ -1407,12 +1414,14 @@
 		/* The spec seems a little ambiguous here, but I think that not
 		 * wrapping context destruction requests makes the most sense.
 		 */
-		status = encode(rqstp, p, obj);
+		gss_wrap_req_encode(encode, rqstp, p, obj);
+		status = 0;
 		goto out;
 	}
 	switch (gss_cred->gc_service) {
 		case RPC_GSS_SVC_NONE:
-			status = encode(rqstp, p, obj);
+			gss_wrap_req_encode(encode, rqstp, p, obj);
+			status = 0;
 			break;
 		case RPC_GSS_SVC_INTEGRITY:
 			status = gss_wrap_req_integ(cred, ctx, encode,