Merge "Remove API races from delete methods"

cinder/db/sqlalchemy/api.py

@@ -1833,6 +1833,12 @@ def volume_update_status_based_on_attachment(context, volume_id):
         return volume_ref
 
 
+def volume_has_snapshots_filter():
+    return sql.exists().where(
+        and_(models.Volume.id == models.Snapshot.volume_id,
+             ~models.Snapshot.deleted))
+
+
 def volume_has_attachments_filter():
     return sql.exists().where(
         and_(models.Volume.id == models.VolumeAttachment.volume_id,