diff --git a/[refs] b/[refs]
index 23a55892b8e4..a8a8479744da 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 4aece6a19cf7f474f15eb861ba74db4479884ce3
+refs/heads/master: 281fe15dc1d6ad46992f18b7a6644269ec5f7138
diff --git a/trunk/fs/nfs/callback_xdr.c b/trunk/fs/nfs/callback_xdr.c
index 56a3cc510107..537f21da6e5f 100644
--- a/trunk/fs/nfs/callback_xdr.c
+++ b/trunk/fs/nfs/callback_xdr.c
@@ -521,6 +521,14 @@ static unsigned encode_cb_sequence_res(struct svc_rqst *rqstp,
 static __be32
 preprocess_nfs41_op(int nop, unsigned int op_nr, struct callback_op **op)
 {
+	if (op_nr == OP_CB_SEQUENCE) {
+		if (nop != 0)
+			return htonl(NFS4ERR_SEQUENCE_POS);
+	} else {
+		if (nop == 0)
+			return htonl(NFS4ERR_OP_NOT_IN_SESSION);
+	}
+
 	switch (op_nr) {
 	case OP_CB_GETATTR:
 	case OP_CB_RECALL: