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

Geert Uytterhoeven
2023-09-10T08:19:47Z

Hi Kent,

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?

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