Re: [PATCH] tmpfs: now working

[Thomas Bushnell, BSG]

Roland McGrath <roland@gnu.org> writes:

> > Faults are, well, ok.  We'll never be able to give them on a
> > default-pager based interface, of course.
> 
> What I'd had in mind was new default_pager_object calls to fix the size of
> a memory object (and clear pages past the new end).  Those changes are
> pretty simple, and make faults work right.

Ok, that's a sane implementation of the truncation part, and I think
it would work just fine.  The default pager currently has no way to
return errors on pagein IIRC, and it's tricky to do right, though.
(Returning such errors is the only way to generate a signal.
Currently the kernel does not track the error code, and so we can't
easily guarantee SIGBUS directly, but we can try.)

That solves one problem; the other is tracking of uses of the object,
and we can just punt that and never track them at all.