> > It seems to me like we should be as honest as possible about it:  For
> > the "avail" category, report the number of available blocks on the
> > read/write filesystem, for "used," report the number of blocks used on
> > both, and for "blocks," add them together.  This should of course be
> > modified if, as you say, the source and target filesystems are the
> > same.
> > 
> 	I submitted a pr for this a while back (cant rememeber if I special
> 	cased both file systems being the same). cgd said he would contact
> 	one of the authors of unionfs - not heard anything since... 

Indeed, I did mention it to the developers of unionfs, and (from quick
inspection of the code) the version in 4.4BSD Lite 2 does in fact do
most of what you want.  (It does everything you said above, except
dealing with the case where upper and lower file systems are the
same.)


... Perhaps when/if Lite2 is integrated into NetBSD, this problem will
be solved.