if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
(backing && *backing == '\0'))
{
+ if (backing) {
+ warn_report("Use of \"backing\": \"\" is deprecated; "
+ "use \"backing\": null instead");
+ }
flags |= BDRV_O_NO_BACKING;
qdict_del(options, "backing");
}