Re: [MAINTAINERS/KERNEL SUMMIT] Trust and maintenance of file systems

Geert Uytterhoeven
2023-09-10T17:26:44Z

On Sun, Sep 10, 2023 at 6:35 PM Kent Overstreet
<kent.overstreet@linux.dev> wrote:
> On Sun, Sep 10, 2023 at 10:19:30AM +0200, Geert Uytterhoeven wrote:
> > On Sun, Sep 10, 2023 at 12:42 AM Kent Overstreet
> > <kent.overstreet@linux.dev> wrote:
> > > On Sat, Sep 09, 2023 at 08:50:39AM -0400, James Bottomley wrote:
> > > > So why can't we figure out that easier way? What's wrong with trying to
> > > > figure out if we can do some sort of helper or library set that assists
> > > > supporting and porting older filesystems. If we can do that it will not
> > > > only make the job of an old fs maintainer a lot easier, but it might
> > > > just provide the stepping stones we need to encourage more people climb
> > > > up into the modern VFS world.
> > >
> > > What if we could run our existing filesystem code in userspace?
> > >
> > > bcachefs has a shim layer (like xfs, but more extensive) to run nearly
> > > the entire filesystem - about 90% by loc - in userspace.
> > >
> > > Right now this is used for e.g. userspace fsck, but one of my goals is
> > > to have the entire filesystem available as a FUSE filesystem. I'd been
> > > planning on doing the fuse port as a straight fuse implementation, but
> > > OTOH if we attempted a sh vfs iops/aops/etc. -> fuse shim, then we would
> > > have pretty much everything we need to run any existing fs (e.g.
> > > reiserfs) as a fuse filesystem.
> > >
> > > It'd be a nontrivial project with some open questions (e.g. do we have
> > > to lift all of bufferheads to userspace?) but it seems worth
> > > investigating.
> >
> > 1. https://xkcd.com/1200/ (not an exact match, but you should get the idea),
> > 2. Once a file system is removed from the kernel, would the user space
> > implementation be maintained better?
>
> This would be for the filesystems that aren't getting maintained and
> tested, to eliminate accidental breakage from in-kernel refactoring and
> changing of APIs.
>
> Getting that code out of the kernel would also greatly help with
> security concerns.

OK, xkcd 1200 it is...

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds