Add scheduler_default_extend_filters option.

Instead of using all default filters of share create operation, use only
necessary list of filters for share extend operation. A new config
option `scheduler_default_extend_filters` is added to provide such list
of filters e.g. CapacityFilter.

Closes-Bug: #1973621
Change-Id: I162325f3096227b74a58b9a55de4660668454d4b

manila/scheduler/drivers/filter.py

@@ -531,8 +531,12 @@ class FilterScheduler(base.Scheduler):
             context, filter_properties, request_spec)
 
         hosts = self.host_manager.get_all_host_states_share(elevated)
+        filter_class_names = None
+        if request_spec.get('is_share_extend', None):
+            filter_class_names = CONF.scheduler_default_extend_filters
         hosts, last_filter = self.host_manager.get_filtered_hosts(
-            hosts, filter_properties)
+            hosts, filter_properties,
+            filter_class_names=filter_class_names)
         hosts = self.host_manager.get_weighed_hosts(hosts, filter_properties)
 
         for tgt_host in hosts:

manila/scheduler/host_manager.py

@@ -69,6 +69,14 @@ host_manager_opts = [
         ],
         help='Which filter class names to use for filtering hosts '
              'creating share group when not specified in the request.'),
+    cfg.ListOpt(
+        'scheduler_default_extend_filters',
+        default=[
+            'CapacityFilter',
+            'DriverFilter',
+        ],
+        help='Which filter class names to use for filtering hosts '
+             'extending share when not specified in the request.'),
 ]
 
 CONF = cfg.CONF

releasenotes/notes/bug-1973621-add-scheduler-default-extend-filters-1c4f2a1863d0d95b.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    When using scheduler filters during share extend, only few filters are
+    necessary. To provide those configurable list of filters for share extend,
+    added new option `scheduler_default_extend_filters`.