Force share server selection on nondisruptive migration

While performing nondisruptive migrations, share servers can not
change, because such thing will cause the migration to be
disruptive, since share servers have different network allocations
and it will cause the destination share to change its export
locations.
This change fixes an issue that allowed manila/the share driver
to chose where a share instance is going to land in case of a
nondisruptive migration. Now, when such migration is required,
manila will automatically place the destination share instance in
the same share server that the source instance is located at.

Closes-Bug: #1920942
Change-Id: I16110ec46c25be65760b15d7fbed67cd005f3873

manila/share/manager.py

@@ -1073,19 +1073,34 @@ class ShareManager(manager.SchedulerDependentManager):
 
         try:
             if dest_share_instance['share_network_id']:
-                rpcapi = share_rpcapi.ShareAPI()
+                # NOTE(carloss): For a nondisruptive migration request, we must
+                # not change the share server, otherwise the share's export
+                # location will change, disconnecting the user. Disruptive
+                # migration requests to the driver the share server.
+                if nondisruptive:
+                    dest_share_server = self._get_share_server_dict(
+                        context, share_server)
+                    dest_share_instance = self.db.share_instance_update(
+                        context,
+                        dest_share_instance['id'],
+                        {'share_server_id': dest_share_server['id']},
+                        with_share_data=True
+                    )
+                else:
+                    rpcapi = share_rpcapi.ShareAPI()
 
-                # NOTE(ganso): Obtaining the share_server_id asynchronously so
-                # we can wait for it to be ready.
-                dest_share_server_id = rpcapi.provide_share_server(
-                    context, dest_share_instance,
-                    dest_share_instance['share_network_id'])
+                    # NOTE(ganso): Obtaining the share_server_id asynchronously
+                    # so we can wait for it to be ready.
+                    dest_share_server_id = rpcapi.provide_share_server(
+                        context, dest_share_instance,
+                        dest_share_instance['share_network_id'])
 
-                rpcapi.create_share_server(
-                    context, dest_share_instance, dest_share_server_id)
+                    rpcapi.create_share_server(
+                        context, dest_share_instance, dest_share_server_id)
+
+                    dest_share_server = helper.wait_for_share_server(
+                        dest_share_server_id)
 
-                dest_share_server = helper.wait_for_share_server(
-                    dest_share_server_id)
             else:
                 dest_share_server = None
 

manila/tests/share/test_manager.py

@@ -5466,6 +5466,8 @@ class ShareManagerTestCase(test.TestCase):
         self.mock_object(
             migration_api.ShareMigrationHelper, 'wait_for_share_server',
             mock.Mock(return_value=dest_server))
+        self.mock_object(self.share_manager.db, 'share_instance_update',
+                         mock.Mock(return_value=migrating_instance))
         self.mock_object(self.share_manager, '_migration_delete_instance')
         self.mock_object(self.share_manager.driver,
                          'migration_check_compatibility',
@@ -5480,7 +5482,7 @@ class ShareManagerTestCase(test.TestCase):
             exception.ShareMigrationFailed,
             self.share_manager._migration_start_driver,
             self.context, share, src_instance, fake_dest_host, True, True,
-            True, not has_snapshots, 'fake_net_id', 'fake_az_id',
+            nondisruptive, not has_snapshots, 'fake_net_id', 'fake_az_id',
             'fake_new_type_id')
 
         # asserts
@@ -5488,13 +5490,23 @@ class ShareManagerTestCase(test.TestCase):
             utils.IsAMatcher(context.RequestContext), 'src_server_id')
         self.share_manager.db.share_instance_get.assert_called_once_with(
             self.context, migrating_instance['id'], with_share_data=True)
-        (rpcapi.ShareAPI.provide_share_server.
-         assert_called_once_with(
-             self.context, migrating_instance, 'fake_net_id'))
-        rpcapi.ShareAPI.create_share_server.assert_called_once_with(
-            self.context, migrating_instance, 'fake_dest_share_server_id')
-        (migration_api.ShareMigrationHelper.wait_for_share_server.
-         assert_called_once_with('fake_dest_share_server_id'))
+        if nondisruptive:
+            self.share_manager.db.share_instance_update.assert_called_with(
+                self.context, migrating_instance['id'],
+                {'share_server_id': src_server['id']},
+                with_share_data=True
+            )
+            rpcapi.ShareAPI.provide_share_server.assert_not_called()
+            rpcapi.ShareAPI.create_share_server.assert_not_called()
+        else:
+            (rpcapi.ShareAPI.provide_share_server.
+                assert_called_once_with(
+                    self.context, migrating_instance, 'fake_net_id'))
+            rpcapi.ShareAPI.create_share_server.assert_called_once_with(
+                self.context, migrating_instance, 'fake_dest_share_server_id')
+            (migration_api.ShareMigrationHelper.wait_for_share_server.
+             assert_called_once_with('fake_dest_share_server_id'))
+
         (api.API.create_share_instance_and_get_request_spec.
          assert_called_once_with(self.context, share, 'fake_az_id', None,
                                  'fake_host', 'fake_net_id',

releasenotes/notes/bug-1920942-fix-migration-server-selection-3ad50e6c73ae03df.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Non-disruptive share migration will no longer choose a different
+    destination server even if limits of shares or gigabytes were exceeded in
+    the source.
+    For more details, please see
+    `bug #1920942 <https://bugs.launchpad.net/manila/+bug/1920942>`_.