Regarding making vnodes freeable:

I recall a paper at a USENIX about 10 years ago (1994?) by a former
coworker of mine at Digital Equipment who did work to make the BSD-based
vnode system used in DEC OSF/1 handle reallocation of vnodes.
There might be some interesting info in there.

ah, here it is:

      Author: Aju John
       Title: Dynamic Vnodes - Design and Implementation
       Pages: 11-23
   Publisher: USENIX 
 Proceedings: USENIX Conference Proceedings
        Date: January 16-20, 1995
    Location: New Orleans, LA
 Institution: Digital Equipment Corporation


-- 
John Kohl <jtk+m1x@kolvir.arlington.ma.us>
Hacking on NetBSD/i386 on occasion.  See also <http://www.NetBSD.org/>.