Fix export location metadata updates by drivers

Drivers can set arbitrary key=value metadata to export
paths. The share manager now checks updates to previously
set metadata when drivers update this metadata with the
"ensure_shares" routine.

Change-Id: Ia42de608ba056d71a1deae2c59bfb43a11672ab7
Partial-Bug: #2053100

manila/db/sqlalchemy/api.py

@@ -4553,9 +4553,17 @@ def _export_locations_update(
                 'deleted': 0,
             })
             el.save(session=context.session)
-            if el['el_metadata']:
+
+            new_export_metadata = next(
+                exl.get('metadata', {})
+                for exl in export_locations
+                if exl['path'] == el['path']
+            )
+            new_export_metadata = new_export_metadata or el['el_metadata']
+
+            if new_export_metadata:
                 _export_location_metadata_update(
-                    context, el['uuid'], el['el_metadata'],
+                    context, el['uuid'], new_export_metadata,
                 )
 
     # Now add new export locations

manila/tests/db/sqlalchemy/test_api.py

@@ -2318,6 +2318,65 @@ class ShareExportLocationsDatabaseAPITestCase(test.TestCase):
         # actual result should contain locations in exact same order
         self.assertEqual(actual_result, update_locations)
 
+    def test_update_export_locations_with_metadata(self):
+        share = db_utils.create_share()
+        original_export_locations = [
+            {
+                'path': 'fake1/1/',
+                'is_admin_only': True,
+                'metadata': {
+                    'foo': 'bar',
+                    'preferred': '1'
+                },
+            },
+            {
+                'path': 'fake2/1/',
+                'is_admin_only': True,
+                'metadata': {
+                    'clem': 'son',
+                    'preferred': '0'
+                },
+            },
+        ]
+
+        # add initial locations
+        db_api.export_locations_update(
+            self.ctxt, share.instance['id'], original_export_locations, False)
+
+        updated_export_locations = [
+            {
+                'path': 'fake1/1/',
+                'is_admin_only': True,
+                'metadata': {
+                    'foo': 'quz',
+                    'preferred': '0'
+                },
+            },
+            {
+                'path': 'fake2/1/',
+                'is_admin_only': True,
+                'metadata': {
+                    'clem': 'son',
+                    'preferred': '1',
+                },
+            },
+        ]
+
+        # update locations
+        db_api.export_locations_update(
+            self.ctxt, share.instance['id'], updated_export_locations, True)
+        actual_result = db_api.export_location_get_all_by_share_id(
+            self.ctxt, share['id'])
+
+        actual_export_locations = [
+            {
+                'path': el['path'],
+                'is_admin_only': el['is_admin_only'],
+                'metadata': el['el_metadata'],
+            } for el in actual_result
+        ]
+        self.assertEqual(updated_export_locations, actual_export_locations)
+
     def test_update_string(self):
         share = db_utils.create_share()
         initial_location = 'fake1/1/'

releasenotes/notes/bug-2053100-fix-export-path-preferred-attr-updates-32db001aacfc8563.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Share manager drivers can now update export location metadata
+    (such as the `preferred` attribute) during the `ensure_shares`
+    routine. (`Launchpad bug: 2053100 <https://launchpad.net/bugs/2053100>`_)