Cinder: Add support to extend attached volumes

While creating an image, if we want to extend the volume
(to accomodate the image), we need to first detach the volume,
perform the extend and attach it again. This is inefficient
for backends that support extending attached volumes since we
are performing 3 cinder operations (the attachment call
includes 3 API calls which sum to a total of 5 API calls for 3
operations) instead of directly extending it which requires only
1 API call to cinder.
The support for extending attached volumes was added in cinder
microversion 3.42.

This patch adds a new boolean config option
``cinder_do_extend_attached`` which allows operators to specify
if the cinder backend they are using supports extending
attached (in-use) volumes. By default this will be ``false``.
Based on the parameter, we will perform the extend operation,
online (if cinder_do_extend_attached is true) and offline otherwise.

Spec: https://review.opendev.org/c/openstack/glance-specs/+/868901

Depends-On: https://review.opendev.org/c/openstack/glance/+/869021
Depends-On: https://review.opendev.org/c/openstack/cinder/+/869051

Change-Id: I5e70824e9abc5277ea25ba95704b358fe3686037

6 files changed, 41 insertions, 9 deletions

diff --git a/glance_store/tests/unit/cinder/test_base.py b/glance_store/tests/unit/cinder/test_base.py
index cc57f56..488cf1a 100644
--- a/glance_store/tests/unit/cinder/test_base.py
+++ b/glance_store/tests/unit/cinder/test_base.py
@@ -104,6 +104,12 @@ class TestBaseBrickConnectorInterface(test_base.StoreBaseTest):
         self.connector.conn.disconnect_volume.assert_called_once_with(
             self.connection_info, fake_device)
 
+    def test_extend_volume(self):
+        self.mock_object(self.connector.conn, 'extend_volume')
+        self.connector.extend_volume()
+        self.connector.conn.extend_volume.assert_called_once_with(
+            self.connection_info)
+
     def test_yield_path(self):
         fake_vol = mock.MagicMock()
         fake_device = 'fake_dev_path'
diff --git a/glance_store/tests/unit/cinder/test_cinder_base.py b/glance_store/tests/unit/cinder/test_cinder_base.py
index d94782f..acdb70b 100644
--- a/glance_store/tests/unit/cinder/test_cinder_base.py
+++ b/glance_store/tests/unit/cinder/test_cinder_base.py
@@ -582,7 +582,7 @@ class TestCinderStoreBase(object):
                 fake_image_id, image_file, expected_size, self.hash_algo,
                 self.context, None)
 
-    def _test_cinder_add_extend(self, is_multi_store=False):
+    def _test_cinder_add_extend(self, is_multi_store=False, online=False):
 
         expected_volume_size = 2 * units.Gi
         expected_multihash = 'fake_hash'
@@ -619,6 +619,11 @@ class TestCinderStoreBase(object):
             backend = 'cinder1'
             expected_location = 'cinder://%s/%s' % (backend, fake_volume.id)
         self.config(cinder_volume_type='some_type', group=backend)
+        if online:
+            self.config(cinder_do_extend_attached=True, group=backend)
+            fake_connector = mock.MagicMock()
+            fake_vol_connector_map = {expected_volume_id: fake_connector}
+            self.store.volume_connector_map = fake_vol_connector_map
 
         fake_client = mock.MagicMock(auth_token=None, management_url=None)
         fake_volume.manager.get.return_value = fake_volume
@@ -635,9 +640,12 @@ class TestCinderStoreBase(object):
                                   side_effect=fake_open), \
                 mock.patch.object(cinder.utils, 'get_hasher') as fake_hasher, \
                 mock.patch.object(cinder.Store, '_wait_volume_status',
-                                  return_value=fake_volume) as mock_wait:
-            mock_cc.return_value = mock.MagicMock(client=fake_client,
-                                                  volumes=fake_volumes)
+                                  return_value=fake_volume) as mock_wait, \
+                mock.patch.object(cinder_utils.API,
+                                  'extend_volume') as extend_vol:
+            mock_cc_return_val = mock.MagicMock(client=fake_client,
+                                                volumes=fake_volumes)
+            mock_cc.return_value = mock_cc_return_val
 
             fake_hasher.side_effect = get_fake_hash
             loc, size, checksum, multihash, metadata = self.store.add(
@@ -656,11 +664,19 @@ class TestCinderStoreBase(object):
                 volume_type='some_type')
             if is_multi_store:
                 self.assertEqual(backend, metadata["store"])
-            fake_volume.extend.assert_called_once_with(
-                fake_volume, expected_volume_size // units.Gi)
-            mock_wait.assert_has_calls(
-                [mock.call(fake_volume, 'creating', 'available'),
-                 mock.call(fake_volume, 'extending', 'available')])
+            if online:
+                extend_vol.assert_called_once_with(
+                    mock_cc_return_val, fake_volume,
+                    expected_volume_size // units.Gi)
+                mock_wait.assert_has_calls(
+                    [mock.call(fake_volume, 'creating', 'available'),
+                     mock.call(fake_volume, 'extending', 'in-use')])
+            else:
+                fake_volume.extend.assert_called_once_with(
+                    fake_volume, expected_volume_size // units.Gi)
+                mock_wait.assert_has_calls(
+                    [mock.call(fake_volume, 'creating', 'available'),
+                     mock.call(fake_volume, 'extending', 'available')])
 
     def test_cinder_add_extend_storage_full(self):
 
diff --git a/glance_store/tests/unit/cinder/test_cinder_store.py b/glance_store/tests/unit/cinder/test_cinder_store.py
index a2b5af7..184acde 100644
--- a/glance_store/tests/unit/cinder/test_cinder_store.py
+++ b/glance_store/tests/unit/cinder/test_cinder_store.py
@@ -138,6 +138,9 @@ class TestCinderStore(base.StoreBaseTest,
     def test_cinder_add_extend(self):
         self._test_cinder_add_extend()
 
+    def test_cinder_add_extend_online(self):
+        self._test_cinder_add_extend(online=True)
+
     def test_cinder_delete(self):
         self._test_cinder_delete()
 
diff --git a/glance_store/tests/unit/cinder/test_multistore_cinder.py b/glance_store/tests/unit/cinder/test_multistore_cinder.py
index 01b27f2..f40965b 100644
--- a/glance_store/tests/unit/cinder/test_multistore_cinder.py
+++ b/glance_store/tests/unit/cinder/test_multistore_cinder.py
@@ -276,6 +276,9 @@ class TestMultiCinderStore(base.MultiStoreBaseTest,
     def test_cinder_add_extend(self):
         self._test_cinder_add_extend(is_multi_store=True)
 
+    def test_cinder_add_extend_online(self):
+        self._test_cinder_add_extend(is_multi_store=True, online=True)
+
     def test_cinder_delete(self):
         self._test_cinder_delete(is_multi_store=True)
 
diff --git a/glance_store/tests/unit/cinder/test_nfs.py b/glance_store/tests/unit/cinder/test_nfs.py
index d0f7d91..aa040ce 100644
--- a/glance_store/tests/unit/cinder/test_nfs.py
+++ b/glance_store/tests/unit/cinder/test_nfs.py
@@ -91,3 +91,6 @@ class TestNfsBrickConnector(
         nfs.mount.umount.assert_called_once_with(
             vol_name, mount_path, self.connector.host,
             self.connector.root_helper)
+
+    def test_extend_volume(self):
+        self.assertRaises(NotImplementedError, self.connector.extend_volume)
diff --git a/glance_store/tests/unit/test_opts.py b/glance_store/tests/unit/test_opts.py
index bfb9bce..073b782 100644
--- a/glance_store/tests/unit/test_opts.py
+++ b/glance_store/tests/unit/test_opts.py
@@ -84,6 +84,7 @@ class OptsTestCase(base.StoreBaseTest):
             'cinder_volume_type',
             'cinder_use_multipath',
             'cinder_enforce_multipath',
+            'cinder_do_extend_attached',
             'default_swift_reference',
             'https_insecure',
             'filesystem_store_chunk_size',