If you want a useful project related to filesystems, try the automounter. Yes, that ancient code.
Look very closely. It has tendrils in NFSv2. And some people, most prominently Theo, use amd(8). Write an automounter that does not depend on NFSv2, and then, most probably we can kill NFSv2. Small steps... It's been that way for ages. But no-one volunteered to work on this.
