[Plugin: Tumblrize] add source from original post to tumblr photo

Hey guys,

i know this is simple php but i just cant seem to figure it out. All i want to do is post a picture in wordpress with just the title of the post and an image. But when it goes to tumblr i want the image to link back to the original wordpress post. I think it has something to do with $postlink? i think its around this part of the code im just not sure what the simple solution is…

// Gather valid data for Tumblr post types.
        if ('photo' === $post_type) {
            $pattern = '/<img.*?src="(.*?)".*?\/?>/';
            $matches = array();
            preg_match($pattern, $post_body, $matches);
            $photo_source = $matches[1];
            $post_body = strip_only($post_body, '<img>');

https://www.ads-software.com/extend/plugins/tumblrize/