SUNRPC: Push svcxdr_init_encode() into svc_process_common()

Now that all vs_dispatch functions invoke svcxdr_init_encode(), it
is common code and can be pushed down into the generic RPC server.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/lockd/svc.c

@@ -704,7 +704,6 @@ static int nlmsvc_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 	if (*statp != rpc_success)
 		return 1;
 
-	svcxdr_init_encode(rqstp);
 	if (!procp->pc_encode(rqstp, &rqstp->rq_res_stream))
 		goto out_encode_err;
 

fs/nfs/callback_xdr.c

@@ -984,8 +984,6 @@ nfs_callback_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 {
 	const struct svc_procedure *procp = rqstp->rq_procinfo;
 
-	svcxdr_init_encode(rqstp);
-
 	*statp = procp->pc_func(rqstp);
 	return 1;
 }

fs/nfsd/nfscache.c

@@ -488,7 +488,7 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
 	case RC_NOCACHE:
 		break;
 	case RC_REPLSTAT:
-		svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
+		xdr_stream_encode_be32(&rqstp->rq_res_stream, rp->c_replstat);
 		rtn = RC_REPLY;
 		break;
 	case RC_REPLBUFF:

fs/nfsd/nfssvc.c

@@ -1052,12 +1052,6 @@ int nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 		goto out_dropit;
 	}
 
-	/*
-	 * Need to grab the location to store the status, as
-	 * NFSv4 does some encoding while processing
-	 */
-	svcxdr_init_encode(rqstp);
-
 	*statp = proc->pc_func(rqstp);
 	if (test_bit(RQ_DROPME, &rqstp->rq_flags))
 		goto out_update_drop;

include/linux/sunrpc/xdr.h

@@ -474,6 +474,27 @@ xdr_stream_encode_u32(struct xdr_stream *xdr, __u32 n)
 	return len;
 }
 
+/**
+ * xdr_stream_encode_be32 - Encode a big-endian 32-bit integer
+ * @xdr: pointer to xdr_stream
+ * @n: integer to encode
+ *
+ * Return values:
+ *   On success, returns length in bytes of XDR buffer consumed
+ *   %-EMSGSIZE on XDR buffer overflow
+ */
+static inline ssize_t
+xdr_stream_encode_be32(struct xdr_stream *xdr, __be32 n)
+{
+	const size_t len = sizeof(n);
+	__be32 *p = xdr_reserve_space(xdr, len);
+
+	if (unlikely(!p))
+		return -EMSGSIZE;
+	*p = n;
+	return len;
+}
+
 /**
  * xdr_stream_encode_u64 - Encode a 64-bit integer
  * @xdr: pointer to xdr_stream

net/sunrpc/svc.c

@@ -1321,6 +1321,7 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *resv)
 	 */
 	if (procp->pc_xdrressize)
 		svc_reserve_auth(rqstp, procp->pc_xdrressize<<2);
+	svcxdr_init_encode(rqstp);
 
 	/* Call the function that processes the request. */
 	rc = process.dispatch(rqstp, statp);