nfsd41: use SEQ4_STATUS_BACKCHANNEL_FAULT when cb_sequence is invalid

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4callback.c

@@ -39,6 +39,8 @@
 
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
+static void nfsd4_mark_cb_fault(struct nfs4_client *, int reason);
+
 #define NFSPROC4_CB_NULL 0
 #define NFSPROC4_CB_COMPOUND 1
 
@@ -460,6 +462,8 @@ static int decode_cb_sequence4resok(struct xdr_stream *xdr,
 	 */
 	status = 0;
 out:
+	if (status)
+		nfsd4_mark_cb_fault(cb->cb_clp, status);
 	return status;
 out_overflow:
 	print_overflow_msg(__func__, xdr);
@@ -686,6 +690,12 @@ static void nfsd4_mark_cb_down(struct nfs4_client *clp, int reason)
 	warn_no_callback_path(clp, reason);
 }
 
+static void nfsd4_mark_cb_fault(struct nfs4_client *clp, int reason)
+{
+	clp->cl_cb_state = NFSD4_CB_FAULT;
+	warn_no_callback_path(clp, reason);
+}
+
 static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 {
 	struct nfs4_client *clp = container_of(calldata, struct nfs4_client, cl_cb_null);

fs/nfsd/nfs4state.c

@@ -1945,8 +1945,14 @@ out:
 
 		nfsd4_get_session(cstate->session);
 		atomic_inc(&clp->cl_refcount);
-		if (clp->cl_cb_state == NFSD4_CB_DOWN)
+		switch (clp->cl_cb_state) {
+		case NFSD4_CB_DOWN:
 			seq->status_flags |= SEQ4_STATUS_CB_PATH_DOWN;
+			break;
+		case NFSD4_CB_FAULT:
+			seq->status_flags |= SEQ4_STATUS_BACKCHANNEL_FAULT;
+			break;
+		}
 	}
 	kfree(conn);
 	spin_unlock(&client_lock);

fs/nfsd/state.h

@@ -258,6 +258,7 @@ struct nfs4_client {
 #define NFSD4_CB_UP		0
 #define NFSD4_CB_UNKNOWN	1
 #define NFSD4_CB_DOWN		2
+#define NFSD4_CB_FAULT		3
 	int			cl_cb_state;
 	struct nfsd4_callback	cl_cb_null;
 	struct nfsd4_session	*cl_cb_session;