public function convertToPlaceholder()
    {
        $bucket = $this->getCloudBucket();
        if ($bucket && !$bucket->isLocalCopyEnabled()) {
            $path = $this->owner->getFullPath();
            CloudAssets::inst()->getLogger()->debug("CloudAssets: converting $path to placeholder");
            Filesystem::makeFolder(dirname($path));
            file_put_contents($path, Config::inst()->get('CloudAssets', 'file_placeholder'));
            clearstatcache();
        }

        return $this->owner;
    }