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

[Christoph Hellwig]

On Mon, Jan 19, 2026 at 06:22:42PM +1100, NeilBrown wrote:
> We are calling it for it's only use.  If there was ever another use, we
> could change the name if that made sense.  It is not a public name, it
> is easy to change.

No, it is not the only use.  This flag needs to be propagate to
userspace through statx or the file attrs.  As I said before there
is plenty of code in userspace that does rely on the traditional
file handle semantics.

> > Remember nfs also support volatile file handles, and other applications
> > might rely on this (I know of quite a few user space applications that
> > do, but they are kinda hardwired to xfs anyway).
> 
> The NFS protocol supports volatile file handles.  knfsd does not.
> So maybe
>   EXPORT_OP_NOT_NFSD_COMPATIBLE
> might be better.  or EXPORT_OP_NOT_LINUX_NFSD_COMPATIBLE.
> (I prefer opt-out rather than opt-in because nfsd export was the
> original purpose of export_operations, but it isn't something
> I would fight for)

Again, stop trying to name things of the initial user.  Flag needs to
describe smenatics, not users.