libvirt: fix disk I/O QOS support with RBD

The disk I/O QOS settings were set in the libvirt_info
method of the Image class. While this is fine for most
subclasses, the Rbd subclass overrides this method and
so was loosing the QOS settings. Move the setting of
QOS parameters into a separate method so it can be
called in all places that need it. For added fun the
commit 86e6f34 which added QOS settings originally never
added any unit tests to cover its operation.

Co-authored: Daniel P. Berrange <berrange@redhat.com>
Fixes bug #1405367
Change-Id: Ibb3a4dff8996c29ef921be7c56648a442bbb89a2

nova/tests/unit/virt/libvirt/test_imagebackend.py

@@ -153,6 +153,37 @@ class _ImageTestCase(object):
             self.assertEqual(fs.source_type, "file")
             self.assertEqual(fs.source_file, image.path)
 
+    def test_libvirt_info(self):
+        image = self.image_class(self.INSTANCE, self.NAME)
+        extra_specs = {
+            'quota:disk_read_bytes_sec': 10 * units.Mi,
+            'quota:disk_read_iops_sec': 1 * units.Ki,
+            'quota:disk_write_bytes_sec': 20 * units.Mi,
+            'quota:disk_write_iops_sec': 2 * units.Ki,
+            'quota:disk_total_bytes_sec': 30 * units.Mi,
+            'quota:disk_total_iops_sec': 3 * units.Ki,
+        }
+
+        disk = image.libvirt_info(disk_bus="virtio",
+                                  disk_dev="/dev/vda",
+                                  device_type="cdrom",
+                                  cache_mode="none",
+                                  extra_specs=extra_specs,
+                                  hypervisor_version=4004001)
+
+        self.assertIsInstance(disk, vconfig.LibvirtConfigGuestDisk)
+        self.assertEqual("/dev/vda", disk.target_dev)
+        self.assertEqual("virtio", disk.target_bus)
+        self.assertEqual("none", disk.driver_cache)
+        self.assertEqual("cdrom", disk.source_device)
+
+        self.assertEqual(10 * units.Mi, disk.disk_read_bytes_sec)
+        self.assertEqual(1 * units.Ki, disk.disk_read_iops_sec)
+        self.assertEqual(20 * units.Mi, disk.disk_write_bytes_sec)
+        self.assertEqual(2 * units.Ki, disk.disk_write_iops_sec)
+        self.assertEqual(30 * units.Mi, disk.disk_total_bytes_sec)
+        self.assertEqual(3 * units.Ki, disk.disk_total_iops_sec)
+
     @mock.patch('nova.virt.disk.api.get_disk_size')
     def test_get_disk_size(self, get_disk_size):
         get_disk_size.return_value = 2361393152
@@ -1336,6 +1367,16 @@ class RbdTestCase(_ImageTestCase, test.NoDBTestCase):
                               self.TEMPLATE_PATH, 1)
             driver_mock.size.assert_called_once_with(image.rbd_name)
 
+    @mock.patch.object(rbd_utils.RBDDriver, "get_mon_addrs")
+    def test_libvirt_info(self, mock_mon_addrs):
+        def get_mon_addrs():
+            hosts = ["server1", "server2"]
+            ports = ["1899", "1920"]
+            return hosts, ports
+        mock_mon_addrs.side_effect = get_mon_addrs
+
+        super(RbdTestCase, self).test_libvirt_info()
+
     @mock.patch.object(rbd_utils.RBDDriver, "get_mon_addrs")
     def test_get_model(self, mock_mon_addrs):
         pool = "FakePool"

nova/virt/libvirt/imagebackend.py

@@ -165,6 +165,11 @@ class Image(object):
         info.driver_name = driver_name
         info.source_path = self.path
 
+        self.disk_qos(info, extra_specs)
+
+        return info
+
+    def disk_qos(self, info, extra_specs):
         tune_items = ['disk_read_bytes_sec', 'disk_read_iops_sec',
             'disk_write_bytes_sec', 'disk_write_iops_sec',
             'disk_total_bytes_sec', 'disk_total_iops_sec']
@@ -173,7 +178,6 @@ class Image(object):
             if len(scope) > 1 and scope[0] == 'quota':
                 if scope[1] in tune_items:
                     setattr(info, scope[1], value)
-        return info
 
     def libvirt_fs_info(self, target, driver_type=None):
         """Get `LibvirtConfigGuestFilesys` filled for this image.
@@ -729,6 +733,9 @@ class Rbd(Image):
         if auth_enabled:
             info.auth_secret_type = 'ceph'
             info.auth_secret_uuid = CONF.libvirt.rbd_secret_uuid
+
+        self.disk_qos(info, extra_specs)
+
         return info
 
     def _can_fallocate(self):