fix setting mtu for ovs internal port (#2247)

pkg/daemon/ovs_linux.go

@@ -443,10 +443,6 @@ func configureMirrorLink(portName string, mtu int) error {
 		return fmt.Errorf("can not find mirror nic %s: %v", portName, err)
 	}
 
-	if err = netlink.LinkSetMTU(mirrorLink, mtu); err != nil {
-		return fmt.Errorf("can not set mirror nic mtu: %v", err)
-	}
-
 	if mirrorLink.Attrs().OperState != netlink.OperUp {
 		if err = netlink.LinkSetUp(mirrorLink); err != nil {
 			return fmt.Errorf("can not set mirror nic %s up: %v", portName, err)
@@ -467,8 +463,13 @@ func configureNic(link, ip string, macAddr net.HardwareAddr, mtu int, detectIPCo
 	}
 
 	if mtu > 0 {
-		if err = netlink.LinkSetMTU(nodeLink, mtu); err != nil {
-			return fmt.Errorf("can not set nic %s mtu: %v", link, err)
+		if nodeLink.Type() == "openvswitch" {
+			_, err = ovs.Exec("set", "interface", link, fmt.Sprintf(`mtu_request=%d`, mtu))
+		} else {
+			err = netlink.LinkSetMTU(nodeLink, mtu)
+		}
+		if err != nil {
+			return fmt.Errorf("failed to set nic %s mtu: %v", link, err)
 		}
 	}
 
@@ -601,9 +602,6 @@ func configProviderNic(nicName, brName string) (int, error) {
 		}
 	}
 
-	if err = netlink.LinkSetMTU(bridge, nic.Attrs().MTU); err != nil {
-		return 0, fmt.Errorf("failed to set MTU of OVS bridge %s: %v", brName, err)
-	}
 	if err = netlink.LinkSetUp(bridge); err != nil {
 		return 0, fmt.Errorf("failed to set OVS bridge %s up: %v", brName, err)
 	}