Followup to address open review comments

This patch is a followup of [1] to address review comments.

[1] https://review.opendev.org/#/c/705876/

Change-Id: I41edec1877106165576ef6bacff24d354460f2ef

cinder/tests/unit/backup/test_backup.py

@@ -1316,6 +1316,9 @@ class BackupTestCase(BaseBackupTest):
         with mock.patch('os.name', os_name):
             self.backup_mgr.restore_backup(self.ctxt, backup, vol2_id)
 
+        vol2.refresh()
+        old_src_backup_id = vol2.metadata["src_backup_id"]
+        self.assertEqual(backup.id, old_src_backup_id)
         vol2.status = 'restoring-backup'
         db.volume_update(self.ctxt, vol2.id, {"status": "restoring-backup"})
         vol2.obj_reset_changes()
@@ -1325,11 +1328,12 @@ class BackupTestCase(BaseBackupTest):
 
         vol2.status = 'available'
         vol2.obj_reset_changes()
-        vol = objects.Volume.get_by_id(self.ctxt, new_vol_id)
-        vol2 = objects.Volume.get_by_id(self.ctxt, vol2_id)
-        self.assertEqual('available', vol['status'])
-        backup = db.backup_get(self.ctxt, backup.id)
+        vol.refresh()
+        vol2.refresh()
+        self.assertEqual('available', vol.status)
+        backup.refresh()
         self.assertEqual(backup.id, vol.metadata["src_backup_id"])
+        self.assertNotEqual(old_src_backup_id, vol2.metadata["src_backup_id"])
         self.assertEqual(backup2.id, vol2.metadata["src_backup_id"])
         self.assertEqual(fields.BackupStatus.AVAILABLE, backup['status'])
 

releasenotes/notes/bp-add-volume-backup-id-e10d053638cb2e78.yaml

@@ -1,7 +1,8 @@
 ---
 features:
   - |
-    Add the property ``src_backup_id`` to the volume's metadata,
+    Added the property ``src_backup_id`` to the volume's metadata,
     to record from which backup the new volume was created.
+    If the ``src_backup_id`` exists in the volume's metadata, it will be updated.
     When restoring from a chain of incremental backups, ``src_backup_id``
     is set to the last incremental backup used for the restore.