Re: [RFC V2 14/18] famfs_fuse: GET_DAXDEV message and daxdev_table

[Darrick J. Wong]

On Thu, Aug 14, 2025 at 03:58:58PM +0200, Miklos Szeredi wrote:
> On Thu, 3 Jul 2025 at 20:54, John Groves <John@xxxxxxxxxx> wrote:
> >
> > * The new GET_DAXDEV message/response is enabled
> > * The command it triggered by the update_daxdev_table() call, if there
> >   are any daxdevs in the subject fmap that are not represented in the
> >   daxdev_dable yet.
> 
> This is rather convoluted, the server *should know* which dax devices
> it has registered, hence it shouldn't need to be explicitly asked.
> 
> And there's already an API for registering file descriptors:
> FUSE_DEV_IOC_BACKING_OPEN.  Is there a reason that interface couldn't
> be used by famfs?

What happens if you want to have a fuse server that hosts both famfs
files /and/ backing files?  That'd be pretty crazy to mix both paths in
one filesystem, but it's in theory possible, particularly if the famfs
server wanted to export a pseudofile where everyone could find that
shadow file?

--D

> Thanks,
> Miklos
>