I did not derive the darwin afs code from netbsd afs code. There was no netbsd code when I was doing the darwin port. J. T. Kohl's NetBSD port came out in Feb 1995, for Transarc 3.3 (I think). Although someone has removed MIT's copyright notice, the Darwin vnode ops clearly derive from the same source. I'm guessing you started with the FreeBSD vnode ops, but originally it was a NetBSD port.