Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Where is fuse going? API cleanup, restructuring and more

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Feb 04, 2026 at 11:43:05AM +0100, Jan Kara wrote:
> On Wed 04-02-26 01:22:02, Joanne Koong wrote:
> > On Mon, Feb 2, 2026 at 11:55 PM Miklos Szeredi <miklos@szeredi.hu> wrote:
> > > > I think that at least one question of interest to the wider fs audience is
> > > >
> > > > Can any of the above improvements be used to help phase out some
> > > > of the old under maintained fs and reduce the burden on vfs maintainers?
> > 
> > I think it might be helpful to know ahead of time where the main
> > hesitation lies. Is it performance? Maybe it'd be helpful if before
> > May there was a prototype converting a simpler filesystem (Darrick and
> > I were musing about fat maybe being a good one) and getting a sense of
> > what the delta is between the native kernel implementation and a
> > fuse-based version? In the past year fuse added a lot of new
> > capabilities that improved performance by quite a bit so I'm curious
> > to see where the delta now lies. Or maybe the hesitation is something
> > else entirely, in which case that's probably a conversation better
> > left for May.
> 
> I'm not sure which filesystems Amir had exactly in mind but in my opinion
> FAT is used widely enough to not be a primary target of this effort. It

OTOH the ESP and USB sticks needn't be high performance.  <shrug>

> would be rather filesystems like (random selection) bfs, adfs, vboxfs,
> minix, efs, freevxfs, etc. The user base of these is very small, testing is
> minimal if possible at all, and thus the value of keeping these in the
> kernel vs the effort they add to infrastructure changes (like folio
> conversions, iomap conversion, ...) is not very favorable.

But yeah, these ones in the long tail are probably good targets.  Though
I think willy pointed out that the biggest barrier in his fs folio
conversions was that many of them aren't testable (e.g. lack mkfs or
fsck tools) which makes a legacy pivot that much harder.

> For these the biggest problem IMO is actually finding someone willing to
> invest into doing (and testing) the conversion. I don't think there are
> severe technical obstacles for most of them.

Yep, that's the biggest hurdle -- convincing managers to pay for a bunch
of really old filesystems that are no longer mainstream.

--D

> 								Honza
> -- 
> Jan Kara <jack@suse.com>
> SUSE Labs, CR
>