Add MTU support to Linux bridge.

Fixes bug 1030932

Added MTU parity to Linux bridge interface driver.

Change-Id: I020b009a32f9317d3bb1224ad03dda291c715e96

quantum/agent/linux/interface.py

@@ -178,6 +178,10 @@ def plug(self, network_id, port_id, device_name, mac_address,
             root_veth, dhcp_veth = ip.add_veth(tap_name, device_name)
             root_veth.link.set_address(mac_address)
 
+            if self.conf.network_device_mtu:
+                root_veth.link.set_mtu(self.conf.network_device_mtu)
+                dhcp_veth.link.set_mtu(self.conf.network_device_mtu)
+
             if namespace:
                 namespace_obj = ip.ensure_namespace(namespace)
                 namespace_obj.add_device_to_namespace(dhcp_veth)

quantum/tests/unit/test_linux_interface.py

@@ -260,7 +260,7 @@ def test_plug_no_ns(self):
     def test_plug_with_ns(self):
         self._test_plug(namespace='01234567-1234-1234-99')
 
-    def _test_plug(self, namespace=None):
+    def _test_plug(self, namespace=None, mtu=None):
         def device_exists(device, root_helper=None, namespace=None):
             return device.startswith('brq')
 
@@ -289,6 +289,9 @@ def device_exists(device, root_helper=None, namespace=None):
                 mock.call().ensure_namespace('01234567-1234-1234-99'),
                 mock.call().ensure_namespace().add_device_to_namespace(
                     ns_veth)])
+        if mtu:
+            ns_veth.assert_has_calls([mock.call.link.set_mtu(mtu)])
+            root_veth.assert_has_calls([mock.call.link.set_mtu(mtu)])
 
         self.ip.assert_has_calls(ip_calls)
 
@@ -306,6 +309,11 @@ def test_plug_dev_exists(self):
             self.ip_dev.assert_has_calls([])
             self.assertEquals(log.call_count, 1)
 
+    def test_plug_mtu(self):
+        self.device_exists.return_value = False
+        self.conf.set_override('network_device_mtu', 9000)
+        self._test_plug(mtu=9000)
+
     def test_unplug(self):
         self.device_exists.return_value = True
         with mock.patch('quantum.agent.linux.interface.LOG.debug') as log: