[PATCH 00/29] fs: require filesystems to explicitly opt-in to nfsd export support

[Christoph Hellwig]

On Wed, Jan 21, 2026 at 10:18:00AM -0500, Jeff Layton wrote:
> > fat seems to be an exception as far as the 'real' file systems go.
> > And it did sound to me like some of the synthetic ones had similar
> > issues.
> > 
> 
> Not sure what we can do about FAT without changing the filehandle
> format in some fashion. The export ops just use
> generic_encode_ino32_fh, and FAT doesn't have stable inode numbers.
> The "nostale" ops seem sane enough but it looks like they only work
> with the fs in r/o mode.

Yeah.  I guess we need to ignore this because of <history>

> > I think Amirs patch would take care of that.  Although userland nfs
> > servers or other storage applications using the handle syscalls would
> > still see them.  Then again fixing the problem that some handles
> > did not fulfill the long standing (but not documented well enough)
> > semantics probably is a good fix on it's own.
> 
> Agreed. We should try to ensure uniqueness and persistence in all
> filehandles both for nfsd and userland applications.

Sounds good to me.