Merge "Avoid BadRequest error log on volume attachment"

nova/volume/cinder.py

@@ -768,6 +768,9 @@ class API(object):
             return _translate_attachment_ref(attachment_ref)
         except cinder_exception.ClientException as ex:
             with excutils.save_and_reraise_exception():
+                # NOTE: It is unnecessary to output BadRequest(400) error log,
+                # because operators don't need to debug such cases.
+                if getattr(ex, 'code', None) != 400:
                     LOG.error(('Create attachment failed for volume '
                                '%(volume_id)s. Error: %(msg)s Code: %(code)s'),
                               {'volume_id': volume_id,