A virtual filesystem standard

[Vincent Wagelaar]

<snip>
> > > > Maybe another idea...
> > > >
> > > > For Linux there exist atm two implementations of a virtual filesystem
> > > > kernel module:
> > > > Lufs (http://lufs.sourceforge.net/lufs/) and
> > > > Fuse (http://sourceforge.net/projects/avf).
> > > > Wouldn't this be an idea (at least for Linux, don't know if other
> > > > os's have something similar).
> > > >
> > > > Instead of using smb:// thumbnails:// ftp://host you would simply map
> > > > it to: $HOME/vfs/smb and $HOME/vfs/thumbnails $HOME/vfs/ftp/host etc.
> > > > Or $HOME/ Desktop. The biggest advantage is that all programs work
> > > > would work out of the box, instead of requiring yet another library.
> > >
> > > There are all sorts of problems with this. Permission issues (need root
> > > to mount), kernel stability issues, no standard async i/o API, not
> > > portable to all unixes, no good way to handle authentication, etc.
> >
> > Smbmount is also suid root (at least on debian). why would we need async
> > io, the current vfs implementations aren't performance monsters either.
> > fuse has limited access to the mounts to the user that has actually
> > mounted it.
>
> Gnome-vfs has asynchronous I/O support, and any replacement needs to
> handle that. Its not about performance, its about not blocking the UI.
> Its possible to layer this over a blocking system using threads, but
> care has to be taken to get things right (enabling cancellation for
> instance).
OK, I understand that, but it looks like glibc has asynchronous io support.
/usr/include/aio.h

> > i would guess that stability would be greater because most code is
> > outside the kernel?
>
> Yeah.
>
> > > Personally i think kernel handling for this is just a bad idea. Fuse is
> > > not a kernel thing. Its a LD_PRELOAD thing. I'm even more strongly
> > > agains that, since it makes all apps slower (talk to uli about
> > > LD_PRELOAD sometime) and breaks the semantics of real system calls.
> >
> > Huh, please reread the website. there are 2 projects. one is fuse (kernel
> > module) and another, avf, that is using the coda filesystem (and an
> > optional ld_preload version for e.g. solaris).
>
> I just followed the Fuse link to http://www.inf.bme.hu/~mszeredi/avfs/
> which mentions LD_PRELOAD. I guess i jumped to conclusion. Anyway, a
> linux-only system isn't interesting at all for the Gnome project.

Their avfscoda implementation seems to me the most interesting because Linux / 
FreeBSD and Solaris have a module for it. So most desktop operating systems 
are covered.

Also pyven uses the same approach: ftp://people.redhat.com/sopwith/

Cheers,
Vincent