In message <20051018231456.GC5656@shorty.gsinet.gsittig.org>Gerhard Sittig writes
>On Tue, Oct 18, 2005 at 14:02 -0700, Bill Studenmund wrote:

[...]
>> > [ hooking syscalls vs generic VFS hooks ]
>> > 
>> > So I thought that a VFS layer would be the way to go -- it's nice and
>> 
>> It is.
>
>Yes, I would not really like to drop the VFS approach and return to
>sycall hooking.  It may work fine (it does for all the other platforms
>Dazuko supports) but it's not half as nice as a VFS layer is.

Just out of curiosity: have you considered using FiST as a template
(no pun intended) for a modular, extensible VFS layer?

FiST is the brainchild of Erez Zadok, who was (if memory serves)
maintainer/re-author of the BSD automount daemon. FiST wrapfs
templates exist for FreeBSD-4 through (more or less) FreeBSD-6.

The VFS layer in FreeBSD-4 shares a recent common ancestor with
NetBSD; if nothing else, it might be a useful starting point.

(Disclaimer: it's no secret that a NetBSD port of FiST is something
I'd like to see happen. I'd also like to see informed commentary on
the changes to the FreeBSD VFS layer that Erez says are necessary to
sport file-system virtualization. Maybe our VFS could use similar
changes; maybe we already have the equivalents.  I dunno, I don't know
enough about the details to say one way or the other.)