Re: [PATCH V12 02/12] famfs: Module operations, fs_context, and mount

[Miklos Szeredi]

On Sat, 22 Aug 2026 at 23:55, John Groves <john@xxxxxxxxxx> wrote:

> Famfs does work in fuse, but some of the asks are things that I don't see
> how I can agree to. I think Miklos and I should discuss those 1:1, to figure
> out if there is a way forward.
>
> I think the virtual backing-dev thing is a non-starter,

The virtual backing-dev is an abstraction.

Is it sufficient for you if I promise that this is going to do the
same thing as the standalone famfs at the same performance level?

>  and I think that the famfs
> portion of the fuse ABI basically can't live without extents that are
> (daxdev, offset, length).

Sigh.  My proposal was (backing-id, offset, length).  Again this is an
abstraction.  A backing ID can be a daxdev, a striped logical device
or it can be a block dev or even a plain file.

> Also, I'm curious: if you don't know of a use case for the striping code outside
> of famfs, why ask famfs to completely rewrite that?  (and I agree, other
> than the eventual remote possibility of competing 'famfs-ng' fuse servers,
> I don't see much likelihood that this piece will be shared.)

Because the striping feature fits much better into a virtual device
API than the extent mapping API.  This is how striping has worked in
linux for the last 30 years.

> Miklos, I trust that you are a good faith actor, although you seem to be
> spread pretty thin. Can you commit to a series of 1:1 conversations with
> me to try to work through the disconnects?

Fine, let's find a time.

Thanks,
Miklos