File disconnect-invalid-two-primaries.patch of Package drbd.28197

diff -Naur drbd-9.0.14+git.62f906cf.orig/drbd/drbd_receiver.c drbd-9.0.14+git.62f906cf/drbd/drbd_receiver.c
--- drbd-9.0.14+git.62f906cf.orig/drbd/drbd_receiver.c	2021-03-25 16:13:54.107048761 +0800
+++ drbd-9.0.14+git.62f906cf/drbd/drbd_receiver.c	2021-03-26 11:00:04.198317636 +0800
@@ -3934,9 +3934,10 @@
 	struct drbd_connection *connection = peer_device->connection;
 	enum drbd_disk_state disk_state;
 	struct net_conf *nc;
-	int hg, rule_nr, rr_conflict, always_asbp, peer_node_id = 0, r;
+	int hg, rule_nr, rr_conflict, always_asbp, peer_node_id = 0, r, pcount;
 	enum drbd_role peer_role = peer_state.role;
 	enum drbd_disk_state peer_disk_state = peer_state.disk;
+	bool two_primaries;
 
 	hg = drbd_handshake(peer_device, &rule_nr, &peer_node_id, true);
 
@@ -3967,11 +3968,17 @@
 	nc = rcu_dereference(connection->transport.net_conf);
 	always_asbp = nc->always_asbp;
 	rr_conflict = nc->rr_conflict;
+	two_primaries = nc ? nc->two_primaries : false;
 	rcu_read_unlock();
+	pcount = (device->resource->role[NOW] == R_PRIMARY)
+		   + (peer_role == R_PRIMARY);
+
+    if (hg == 0 && pcount == 2 && !two_primaries) {
+        drbd_alert(device, "Dual primaries detected with unified UUID but not allowed, drop connection!\n");
+        return -1;
+    }
 
 	if (hg == 100 || (hg == -100 && always_asbp)) {
-		int pcount = (device->resource->role[NOW] == R_PRIMARY)
-			   + (peer_role == R_PRIMARY);
 		int forced = (hg == -100);
 
 		if (device->resource->res_opts.quorum != QOU_OFF &&