Log information about the Ceph v2 clone API

Starting with the Mimic release and the Ceph RBD clone v2 feature,
it is no longer necessary to manage snapshot protection status.
The usage of clone v2 is controlled via the Ceph “rbd default
clone format” configuration option which defaults to “auto”, but
can be overridden to “1” to force the legacy clone v1 behavior or
“2” to force the new clonev2 behavior.

This must be configured in Ceph, it's not something that can be
configured on the Cinder side.

As an alternative, setting the minimum client to mimic
"$ ceph osd set-require-min-compat-client mimic"

Above all with Ceph RBD clone v2 support enabled, image snapshots
can be cloned without marking the snapshot as protected because
RBD automatically tracks the usage of the snapshot by clones. As
a result Ceph RBD clone v2 API improves performance.

This proposed patch adds logging messages for the operator
indicating whether Ceph has been configured to use the Ceph RBD
v2 clone feature.

In this way the operator can consult with the Ceph administrator
to take appropriate action.

You can determine which volumes are using the clone v2 feature
thanks to volume.volume.op_features(). It returns a value depending
on the v2 clone api being enabled or not.

Co-authored-by: Eric Harney <eharney@redhat.com>
Change-Id: Ib52879a270a4ae4cdd3cb5fc18f2b7bdbccd8ab5

cinder/tests/unit/volume/drivers/test_rbd.py

@@ -869,6 +869,71 @@ class RBDTestCase(test.TestCase):
         proxy.create_snap.assert_called_with(*args)
         proxy.protect_snap.assert_called_with(*args)
 
+    @common_mocks
+    @mock.patch('cinder.objects.Volume.get_by_id')
+    @mock.patch.object(driver.RBDDriver, '_resize', mock.Mock())
+    def test_log_create_vol_from_snap_w_v2_clone_api(self, volume_get_by_id):
+        volume_get_by_id.return_value = self.volume_a
+
+        self.mock_proxy().__enter__().volume.op_features.return_value = 1
+        self.mock_rbd.RBD_OPERATION_FEATURE_CLONE_PARENT = 1
+
+        snapshot = mock.Mock()
+        self.cfg.rbd_flatten_volume_from_snapshot = False
+
+        with mock.patch.object(driver, 'LOG') as \
+                mock_log:
+
+            self.driver.create_volume_from_snapshot(self.volume_a, snapshot)
+
+            mock_log.info.assert_called_once_with(mock.ANY)
+            mock_log.warning.assert_not_called()
+            self.assertTrue(self.driver._clone_v2_api_checked)
+
+    @common_mocks
+    @mock.patch('cinder.objects.Volume.get_by_id')
+    @mock.patch.object(driver.RBDDriver, '_resize', mock.Mock())
+    def test_log_create_vol_from_snap_without_v2_clone_api(self,
+                                                           volume_get_by_id):
+        volume_get_by_id.return_value = self.volume_a
+
+        self.mock_proxy().__enter__().volume.op_features.return_value = 0
+        self.mock_rbd.RBD_OPERATION_FEATURE_CLONE_PARENT = 0
+
+        snapshot = mock.Mock()
+        self.cfg.rbd_flatten_volume_from_snapshot = False
+
+        with mock.patch.object(driver, 'LOG') as \
+                mock_log:
+
+            self.driver.create_volume_from_snapshot(self.volume_a, snapshot)
+
+            mock_log.warning.assert_called_once_with(mock.ANY)
+            mock_log.info.assert_not_called()
+            self.assertTrue(self.driver._clone_v2_api_checked)
+
+    @common_mocks
+    @mock.patch('cinder.objects.Volume.get_by_id')
+    @mock.patch.object(driver.RBDDriver, '_resize', mock.Mock())
+    def test_log_create_vol_from_snap_without_v2_clone_api_2(self,
+                                                             volume_get_by_id):
+        volume_get_by_id.return_value = self.volume_a
+
+        self.mock_proxy().__enter__().volume.op_features.return_value = 0
+        self.mock_rbd.RBD_OPERATION_FEATURE_CLONE_PARENT = 1
+
+        snapshot = mock.Mock()
+        self.cfg.rbd_flatten_volume_from_snapshot = False
+
+        with mock.patch.object(driver, 'LOG') as \
+                mock_log:
+
+            self.driver.create_volume_from_snapshot(self.volume_a, snapshot)
+
+            mock_log.warning.assert_called_once_with(mock.ANY)
+            mock_log.info.assert_not_called()
+            self.assertTrue(self.driver._clone_v2_api_checked)
+
     @common_mocks
     @mock.patch('cinder.objects.Volume.get_by_id')
     def test_delete_snapshot(self, volume_get_by_id):

cinder/volume/drivers/rbd.py

@@ -246,6 +246,7 @@ class RBDDriver(driver.CloneableImageVD, driver.MigrateVD,
         self._is_replication_enabled = False
         self._replication_targets = []
         self._target_names = []
+        self._clone_v2_api_checked = False
 
         if self.rbd is not None:
             self.RBD_FEATURE_LAYERING = self.rbd.RBD_FEATURE_LAYERING
@@ -268,6 +269,22 @@ class RBDDriver(driver.CloneableImageVD, driver.MigrateVD,
             'max_over_subscription_ratio', 'volume_dd_blocksize')
         return RBD_OPTS + additional_opts
 
+    def _show_msg_check_clone_v2_api(self, volume_name):
+        if not self._clone_v2_api_checked:
+            self._clone_v2_api_checked = True
+            with RBDVolumeProxy(self, volume_name) as volume:
+                try:
+                    if (volume.volume.op_features() &
+                            self.rbd.RBD_OPERATION_FEATURE_CLONE_PARENT):
+                        LOG.info('Using v2 Clone API')
+                        return
+                except AttributeError:
+                    pass
+                LOG.warning('Not using v2 clone API, please upgrade to'
+                            ' mimic+ and set the OSD minimum client'
+                            ' compat version to mimic for better'
+                            ' performance, fewer deletion issues')
+
     def _get_target_config(self, target_id):
         """Get a replication target from known replication targets."""
         for target in self._replication_targets:
@@ -1000,6 +1017,8 @@ class RBDDriver(driver.CloneableImageVD, driver.MigrateVD,
             self._flatten(self.configuration.rbd_pool, volume.name)
         if int(volume.size):
             self._resize(volume)
+
+        self._show_msg_check_clone_v2_api(snapshot.volume_name)
         return volume_update
 
     def _delete_backup_snaps(self, rbd_image):