SUNRPC: New xdr_streams XDR decoder API

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

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/fs/nfs/mount_clnt.c b/fs/nfs/mount_clnt.c
index 979ebd7..697e072 100644
--- a/fs/nfs/mount_clnt.c
+++ b/fs/nfs/mount_clnt.c
@@ -340,18 +340,16 @@
 	return 0;
 }
 
-static int mnt_dec_mountres(struct rpc_rqst *req, __be32 *p,
-			    struct mountres *res)
+static int mnt_xdr_dec_mountres(struct rpc_rqst *req,
+				struct xdr_stream *xdr,
+				struct mountres *res)
 {
-	struct xdr_stream xdr;
 	int status;
 
-	xdr_init_decode(&xdr, &req->rq_rcv_buf, p);
-
-	status = decode_status(&xdr, res);
+	status = decode_status(xdr, res);
 	if (unlikely(status != 0 || res->errno != 0))
 		return status;
-	return decode_fhandle(&xdr, res);
+	return decode_fhandle(xdr, res);
 }
 
 static int decode_fhs_status(struct xdr_stream *xdr, struct mountres *res)
@@ -434,30 +432,28 @@
 	return 0;
 }
 
-static int mnt_dec_mountres3(struct rpc_rqst *req, __be32 *p,
-			     struct mountres *res)
+static int mnt_xdr_dec_mountres3(struct rpc_rqst *req,
+				 struct xdr_stream *xdr,
+				 struct mountres *res)
 {
-	struct xdr_stream xdr;
 	int status;
 
-	xdr_init_decode(&xdr, &req->rq_rcv_buf, p);
-
-	status = decode_fhs_status(&xdr, res);
+	status = decode_fhs_status(xdr, res);
 	if (unlikely(status != 0 || res->errno != 0))
 		return status;
-	status = decode_fhandle3(&xdr, res);
+	status = decode_fhandle3(xdr, res);
 	if (unlikely(status != 0)) {
 		res->errno = -EBADHANDLE;
 		return 0;
 	}
-	return decode_auth_flavors(&xdr, res);
+	return decode_auth_flavors(xdr, res);
 }
 
 static struct rpc_procinfo mnt_procedures[] = {
 	[MOUNTPROC_MNT] = {
 		.p_proc		= MOUNTPROC_MNT,
 		.p_encode	= (kxdreproc_t)mnt_xdr_enc_dirpath,
-		.p_decode	= (kxdrproc_t)mnt_dec_mountres,
+		.p_decode	= (kxdrdproc_t)mnt_xdr_dec_mountres,
 		.p_arglen	= MNT_enc_dirpath_sz,
 		.p_replen	= MNT_dec_mountres_sz,
 		.p_statidx	= MOUNTPROC_MNT,
@@ -476,7 +472,7 @@
 	[MOUNTPROC3_MNT] = {
 		.p_proc		= MOUNTPROC3_MNT,
 		.p_encode	= (kxdreproc_t)mnt_xdr_enc_dirpath,
-		.p_decode	= (kxdrproc_t)mnt_dec_mountres3,
+		.p_decode	= (kxdrdproc_t)mnt_xdr_dec_mountres3,
 		.p_arglen	= MNT_enc_dirpath_sz,
 		.p_replen	= MNT_dec_mountres3_sz,
 		.p_statidx	= MOUNTPROC3_MNT,