NFSD: Replace READ* macros in nfsd4_decode_backchannel_ctl()

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4xdr.c

@@ -788,17 +788,6 @@ nfsd4_decode_access(struct nfsd4_compoundargs *argp,
 	return nfs_ok;
 }
 
-static __be32 nfsd4_decode_backchannel_ctl(struct nfsd4_compoundargs *argp, struct nfsd4_backchannel_ctl *bc)
-{
-	DECODE_HEAD;
-
-	READ_BUF(4);
-	bc->bc_cb_program = be32_to_cpup(p++);
-	nfsd4_decode_cb_sec(argp, &bc->bc_cb_sec);
-
-	DECODE_TAIL;
-}
-
 static __be32 nfsd4_decode_bind_conn_to_session(struct nfsd4_compoundargs *argp, struct nfsd4_bind_conn_to_session *bcts)
 {
 	DECODE_HEAD;
@@ -1483,6 +1472,13 @@ nfsd4_decode_release_lockowner(struct nfsd4_compoundargs *argp, struct nfsd4_rel
 	return nfs_ok;
 }
 
+static __be32 nfsd4_decode_backchannel_ctl(struct nfsd4_compoundargs *argp, struct nfsd4_backchannel_ctl *bc)
+{
+	if (xdr_stream_decode_u32(argp->xdr, &bc->bc_cb_program) < 0)
+		return nfserr_bad_xdr;
+	return nfsd4_decode_cb_sec(argp, &bc->bc_cb_sec);
+}
+
 static __be32
 nfsd4_decode_exchange_id(struct nfsd4_compoundargs *argp,
 			 struct nfsd4_exchange_id *exid)