[Unity] Implements default filter function

Implements the default filter function for Unity driver, if the
share size is smaller than 3GB, will not schedule the share
creation to Unity backend.

Change-Id: Iebb5063d4e1c4c2f5ddce0d5000b7d51dcb0605b
Closes-bug: #1652379

doc/source/configuration/shared-file-systems/drivers/dell-emc-unity-driver.rst

@@ -135,6 +135,7 @@ for the Unity driver.
     unity_ethernet_ports = <comma separated ports list>
     driver_handles_share_servers = True/False
     unity_share_server = <name of NAS server in Unity system>
+    report_default_filter_function = True/False
 
 - `emc_share_backend`
     The plugin name. Set it to `unity` for the Unity driver.
@@ -192,6 +193,13 @@ for the Unity driver.
     One of NAS server names in Unity, it is used for share creation when
     the driver is in `DHSS=False` mode.
 
+- `report_default_filter_function`
+    Whether or not report default filter function. Default value is False.
+    However, this value will be changed to True in a future release to ensure
+    compliance with design expectations in Manila. So we recommend always
+    setting this option in your deployment to True or False per your desired
+    behavior.
+
 Restart of :term:`manila-share` service is needed for the configuration
 changes to take effect.
 
@@ -444,6 +452,22 @@ balanced ports per storage processor. For example:
    # Use eth2 from both SPs
    unity_ethernet_ports = spa_eth2, spb_eth2
 
+
+Default filter function
+-----------------------
+
+Unity does not support the file system creation with size smaller than 3GB, if
+the size of share user create is smaller than 3GB, Unity driver will supplement
+the size to 3GB in Unity.
+
+Unity driver implemented the get_default_filter_function API to report the
+default filter function, if the share size is smaller than 3GB, Manila will
+not schedule the share creation to Unity backend.
+
+Unity driver provides an option ``report_default_filter_function`` to disable
+or enable the filter function reporting, the default value is disabled.
+
+
 Restrictions
 ------------
 
@@ -483,6 +507,7 @@ Following driver features are implemented in the plugin.
   parameters.
 * teardown_server: Tear down the share server.
 * revert_to_snapshot: Revert a share to a snapshot.
+* get_default_filter_function: Report a default filter function.
 
 
 Driver options

manila/share/drivers/dell_emc/driver.py

@@ -308,3 +308,8 @@ class EMCShareDriver(driver.ShareDriver):
                                                   share_server)
         else:
             raise NotImplementedError()
+
+    def get_default_filter_function(self):
+        if hasattr(self.plugin, 'get_default_filter_function'):
+            return self.plugin.get_default_filter_function()
+        return None

manila/share/drivers/dell_emc/plugins/unity/connection.py

@@ -42,9 +42,10 @@ from manila import utils
      7.0.1 - Fix parsing management IPv6 address
      7.0.2 - Bugfix: failed to delete CIFS share if wrong access was set
      8.0.0 - Supports manage/unmanage share server/share/snapshot
+     9.0.0 - Implements default filter function
 """
 
-VERSION = "8.0.0"
+VERSION = "9.0.0"
 
 LOG = log.getLogger(__name__)
 SUPPORTED_NETWORK_TYPES = (None, 'flat', 'vlan')
@@ -72,6 +73,9 @@ UNITY_OPTS = [
                help='NAS server used for creating share when driver '
                     'is in DHSS=False mode. It is required when '
                     'driver_handles_share_servers=False in manila.conf.'),
+    cfg.StrOpt('report_default_filter_function',
+               default=False,
+               help='Whether or not report default filter function.'),
 ]
 
 CONF = cfg.CONF
@@ -143,6 +147,8 @@ class UnityStorageConnection(driver.StorageConnection):
         self.validate_port_configuration(self.port_ids_conf)
         pool_name = config.unity_server_meta_pool
         self._config_pool(pool_name)
+        self.report_default_filter_function = config.safe_get(
+            'report_default_filter_function')
 
     def get_server_name(self, share_server=None):
         if not self.driver_handles_share_servers:
@@ -894,3 +900,8 @@ class UnityStorageConnection(driver.StorageConnection):
         """Reverts a share (in place) to the specified snapshot."""
         snapshot_id = unity_utils.get_snapshot_id(snapshot)
         return self.client.restore_snapshot(snapshot_id)
+
+    def get_default_filter_function(self):
+        if self.report_default_filter_function:
+            return "share.size >= 3"
+        return None

manila/tests/share/drivers/dell_emc/plugins/unity/res_mock.py

@@ -354,6 +354,7 @@ def do_connection_connect(conn, res):
     conn.port_set = set(['spa_eth1', 'spa_eth2'])
     conn.nas_server_pool = StorageObjectMock(res['nas_server_pool'])
     conn.storage_processor = StorageObjectMock(res['sp_a'])
+    conn.report_default_filter_function = False
 
 
 def patch_connection(func):

manila/tests/share/drivers/dell_emc/plugins/unity/test_connection.py

@@ -882,3 +882,20 @@ class TestConnection(test.TestCase):
         self.assertRaises(exception.ManageInvalidShare,
                           connection.manage_existing_with_server,
                           share, driver_options, share_server)
+
+    @res_mock.mock_manila_input
+    @res_mock.patch_connection
+    def test_get_default_filter_function_disable_report(self, connection,
+                                                        mocked_input):
+        expected = None
+        actual = connection.get_default_filter_function()
+        self.assertEqual(expected, actual)
+
+    @res_mock.mock_manila_input
+    @res_mock.patch_connection
+    def test_get_default_filter_function_enable_report(self, connection,
+                                                       mocked_input):
+        expected = "share.size >= 3"
+        connection.report_default_filter_function = True
+        actual = connection.get_default_filter_function()
+        self.assertEqual(expected, actual)

manila/tests/share/drivers/dell_emc/test_driver.py

@@ -116,6 +116,7 @@ class EMCShareFrameworkTestCase(test.TestCase):
     def test_update_share_stats(self):
         data = {}
         self.driver.plugin = mock.Mock()
+        self.driver.plugin.get_default_filter_function.return_value = None
         self.driver._update_share_stats()
         data["share_backend_name"] = FAKE_BACKEND
         data["driver_handles_share_servers"] = True
@@ -203,3 +204,8 @@ class EMCShareFrameworkTestCase(test.TestCase):
         self.driver.unmanage_snapshot(snapshot)
         self.driver.unmanage_snapshot_with_server(snapshot, share_server)
         self.driver.unmanage_server(server_details)
+
+    def test_get_default_filter_function(self):
+        expected = None
+        actual = self.driver.get_default_filter_function()
+        self.assertEqual(expected, actual)

releasenotes/notes/unity-default-filter-function-support-2eefc8044a5add5d.yaml

@@ -0,0 +1,4 @@
+---
+features:
+  - |
+    Dell EMC Unity: Default filter function support for 3GB share size.