libvirt: Reduce calls to qemu-img during update_available_resource

I464bc2b88123a012cd12213beac4b572c3c20a56 introduced a second call to
``qemu-img`` that can easily be collapsed into one with the addition of
a new call within the disk_api.

Related-Bug: #1785827
Change-Id: Ibfd0527ed79f60282b542034d7cb97b424becba3

Author: lyarwood

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

@@ -4642,7 +4642,8 @@ def test_serial_console_release_port(
             [mock.call(host='127.0.0.1', port=10000),
              mock.call(host='127.0.0.1', port=10001)])
 
-    @mock.patch('nova.virt.disk.api.get_disk_size', return_value=0)
+    @mock.patch('nova.virt.disk.api.get_disk_info',
+                return_value=mock.Mock(disk_size=0))
     @mock.patch('nova.virt.libvirt.storage.lvm.get_volume_size',
                 return_value='fake-size')
     def test_detach_encrypted_volumes(self, mock_get_volume_size,
@@ -9421,12 +9422,9 @@ def mock_lookup_side_effect(name):
             return mock_virDomain
         mock_lookup.side_effect = mock_lookup_side_effect
 
-        mock_getsize = mock.Mock()
-        mock_getsize.return_value = "10737418240"
-        mock_get_virtual_size = mock.Mock()
-        mock_get_virtual_size.return_value = "10737418240"
-
-        return (mock_getsize, mock_get_virtual_size, mock_lookup)
+        mock_qemu_img_info = mock.Mock(disk_size=10737418240,
+                                       virtual_size=10737418240)
+        return (mock_qemu_img_info, mock_lookup)
 
     def test_is_shared_block_storage_rbd(self):
         self.flags(images_type='rbd', group='libvirt')
@@ -9519,7 +9517,7 @@ def test_is_shared_block_storage_volume_backed(self):
                   {'connection_info': 'info', 'mount_device': '/dev/vda'}]}
         instance = objects.Instance(**self.test_instance)
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
-        (mock_getsize, mock_get_virtual_size, mock_lookup) =\
+        (mock_qemu_img_info, mock_lookup) =\
             self._is_shared_block_storage_test_create_mocks(disks)
         data = objects.LibvirtLiveMigrateData(is_volume_backed=True,
                                               is_shared_instance_path=False)
@@ -9543,21 +9541,18 @@ def test_is_shared_block_storage_volume_backed_with_disk(self):
                   {'connection_info': 'info', 'mount_device': '/dev/vda'}]}
         instance = objects.Instance(**self.test_instance)
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
-        (mock_getsize, mock_get_virtual_size, mock_lookup) =\
+        (mock_qemu_img_info, mock_lookup) =\
             self._is_shared_block_storage_test_create_mocks(disks)
         data = objects.LibvirtLiveMigrateData(is_volume_backed=True,
                                               is_shared_instance_path=False)
         with test.nested(
                 mock.patch.object(libvirt_driver.disk_api,
-                                  'get_allocated_disk_size', mock_getsize),
-                mock.patch.object(libvirt_driver.disk_api,
-                                  'get_disk_size', mock_get_virtual_size),
+                                  'get_disk_info', mock_qemu_img_info),
                 mock.patch.object(host.Host, '_get_domain', mock_lookup)):
             self.assertFalse(drvr._is_shared_block_storage(
                                     instance, data,
                                     block_device_info = bdi))
-        mock_getsize.assert_called_once_with('/instance/disk.local')
-        mock_get_virtual_size.assert_called_once_with('/instance/disk.local')
+        mock_qemu_img_info.assert_called_once_with('/instance/disk.local')
         mock_lookup.assert_called_once_with(instance)
 
     def test_is_shared_block_storage_nfs(self):
@@ -12370,12 +12365,8 @@ def test_pre_live_migration_with_perf_events(self):
                                       migrate_data=migrate_data)
         self.assertEqual(['cmt'], res.supported_perf_events)
 
-    @mock.patch('nova.virt.disk.api.get_disk_size',
-                side_effect=[10737418240, 21474836480])
-    @mock.patch('nova.virt.disk.api.get_allocated_disk_size',
-                side_effect=[10737418240, 3328599655])
-    def test_get_instance_disk_info_works_correctly(self, mock_get_alloc,
-                                                    mock_get_disk_size):
+    @mock.patch('nova.virt.disk.api.get_disk_info')
+    def test_get_instance_disk_info_works_correctly(self, mock_qemu_img_info):
         # Test data
         instance = objects.Instance(**self.test_instance)
         dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
@@ -12392,6 +12383,11 @@ def test_get_instance_disk_info_works_correctly(self, mock_get_alloc,
         vdmock = mock.Mock(autospec=fakelibvirt.virDomain)
         vdmock.XMLDesc.return_value = dummyxml
 
+        mock_qemu_img_info.side_effect = [
+            mock.Mock(disk_size=10737418240, virtual_size=10737418240),
+            mock.Mock(disk_size=3328599655, virtual_size=21474836480)
+        ]
+
         def fake_lookup(_uuid):
             if _uuid == instance.uuid:
                 return vdmock
@@ -12416,12 +12412,9 @@ def fake_lookup(_uuid):
         self.assertEqual(info[1]['over_committed_disk_size'], 18146236825)
 
         vdmock.XMLDesc.assert_called_once_with(0)
-        mock_get_alloc.assert_has_calls([mock.call('/test/disk'),
-                                         mock.call('/test/disk.local')])
-        self.assertEqual(2, mock_get_alloc.call_count)
-        mock_get_disk_size.assert_has_calls([mock.call('/test/disk'),
+        mock_qemu_img_info.assert_has_calls([mock.call('/test/disk'),
                                              mock.call('/test/disk.local')])
-        self.assertEqual(2, mock_get_disk_size.call_count)
+        self.assertEqual(2, mock_qemu_img_info.call_count)
 
     def test_post_live_migration(self):
         vol = {'block_device_mapping': [
@@ -12508,12 +12501,9 @@ def _test(mock_get_bdms, mock_attachment_get, mock_disconnect):
                                                     instance)
         _test()
 
-    @mock.patch('nova.virt.disk.api.get_disk_size',
-                side_effect=[10737418240, 21474836480])
-    @mock.patch('nova.virt.disk.api.get_allocated_disk_size',
-                side_effect=[10737418240, 3328599655])
+    @mock.patch('nova.virt.disk.api.get_disk_info')
     def test_get_instance_disk_info_excludes_volumes(
-            self, mock_get_alloc, mock_get_disk_size):
+            self, mock_qemu_img_info):
         # Test data
         instance = objects.Instance(**self.test_instance)
         dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
@@ -12536,6 +12526,11 @@ def test_get_instance_disk_info_excludes_volumes(
         vdmock = mock.Mock(autospec=fakelibvirt.virDomain)
         vdmock.XMLDesc.return_value = dummyxml
 
+        mock_qemu_img_info.side_effect = [
+            mock.Mock(disk_size=10737418240, virtual_size=10737418240),
+            mock.Mock(disk_size=3328599655, virtual_size=21474836480)
+        ]
+
         def fake_lookup(_uuid):
             if _uuid == instance.uuid:
                 return vdmock
@@ -12565,19 +12560,12 @@ def fake_lookup(_uuid):
         self.assertEqual(info[1]['over_committed_disk_size'], 18146236825)
 
         vdmock.XMLDesc.assert_called_once_with(0)
-        mock_get_alloc.assert_has_calls([mock.call('/test/disk'),
-                                         mock.call('/test/disk.local')])
-        self.assertEqual(2, mock_get_alloc.call_count)
-        mock_get_disk_size.assert_has_calls([mock.call('/test/disk'),
+        mock_qemu_img_info.assert_has_calls([mock.call('/test/disk'),
                                              mock.call('/test/disk.local')])
-        self.assertEqual(2, mock_get_disk_size.call_count)
+        self.assertEqual(2, mock_qemu_img_info.call_count)
 
-    @mock.patch('nova.virt.disk.api.get_disk_size',
-                return_value=10737418240)
-    @mock.patch('nova.virt.disk.api.get_allocated_disk_size',
-                return_value=10737418240)
-    def test_get_instance_disk_info_no_bdinfo_passed(
-            self, mock_get_alloc, mock_get_disk_size):
+    @mock.patch('nova.virt.disk.api.get_disk_info')
+    def test_get_instance_disk_info_no_bdinfo_passed(self, mock_qemu_img_info):
         # NOTE(ndipanov): _get_disk_overcomitted_size_total calls this method
         # without access to Nova's block device information. We want to make
         # sure that we guess volumes mostly correctly in that case as well
@@ -12598,6 +12586,9 @@ def test_get_instance_disk_info_no_bdinfo_passed(
         vdmock = mock.Mock(autospec=fakelibvirt.virDomain)
         vdmock.XMLDesc.return_value = dummyxml
 
+        mock_qemu_img_info.return_value = mock.Mock(disk_size=10737418240,
+                                                    virtual_size=10737418240)
+
         def fake_lookup(_uuid):
             if _uuid == instance.uuid:
                 return vdmock
@@ -12616,8 +12607,7 @@ def fake_lookup(_uuid):
         self.assertEqual(info[0]['over_committed_disk_size'], 0)
 
         vdmock.XMLDesc.assert_called_once_with(0)
-        mock_get_alloc.assert_called_once_with(path)
-        mock_get_disk_size.assert_called_once_with(path)
+        mock_qemu_img_info.assert_called_once_with(path)
 
     def test_spawn_with_network_info(self):
         def fake_getLibVersion():

nova/virt/disk/api.py

@@ -89,6 +89,15 @@ def resize2fs(image, check_exit_code=False, run_as_root=False):
             nova.privsep.fs.unprivileged_resize2fs(image, check_exit_code)
 
 
+def get_disk_info(path):
+    """Get QEMU info of a disk image
+
+    :param path: Path to the disk image
+    :returns: oslo_utils.imageutils.QemuImgInfo object for the image.
+    """
+    return images.qemu_img_info(path)
+
+
 def get_disk_size(path):
     """Get the (virtual) size of a disk image
 

nova/virt/libvirt/driver.py

@@ -8057,17 +8057,18 @@ def _get_instance_disk_info_from_config(self, guest_config,
             # get the real disk size or
             # raise a localized error if image is unavailable
             if disk_type == 'file':
+                qemu_img_info = disk_api.get_disk_info(path)
                 if driver_type == 'ploop':
                     dk_size = 0
                     for dirpath, dirnames, filenames in os.walk(path):
                         for f in filenames:
                             fp = os.path.join(dirpath, f)
                             dk_size += os.path.getsize(fp)
                 else:
-                    dk_size = disk_api.get_allocated_disk_size(path)
+                    dk_size = qemu_img_info.disk_size
 
                 # NOTE(lyarwood): Fetch the virtual size for all file disks.
-                virt_size = disk_api.get_disk_size(path)
+                virt_size = qemu_img_info.virtual_size
 
             elif disk_type == 'block' and block_device_info:
                 # FIXME(lyarwood): There's no reason to use a separate call