linux-kernel - Re: [PATCH 0/4] exportfs: add flag to allow marking export operations as only supporting file handles

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Message-ID: <CAOQ4uxjPSmrvy44AdahKjzFOcydKN8t=xBnS_bhV-vC+UBdPUg@mail.gmail.com>
Date: Thu, 5 Dec 2024 12:57:28 +0100
From: Amir Goldstein <amir73il@...il.com>
To: Christoph Hellwig <hch@...radead.org>
Cc: Christian Brauner <brauner@...nel.org>, Jeff Layton <jlayton@...nel.org>, 
	Erin Shepherd <erin.shepherd@....eu>, Chuck Lever <chuck.lever@...cle.com>, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-nfs@...r.kernel.org, stable <stable@...nel.org>
Subject: Re: [PATCH 0/4] exportfs: add flag to allow marking export operations
 as only supporting file handles

On Thu, Dec 5, 2024 at 1:38 AM Christoph Hellwig <hch@...radead.org> wrote:
>
> On Sun, Dec 01, 2024 at 02:12:24PM +0100, Christian Brauner wrote:
> > Hey,
> >
> > Some filesystems like kernfs and pidfs support file handles as a
> > convenience to enable the use of name_to_handle_at(2) and
> > open_by_handle_at(2) but don't want to and cannot be reliably exported.
> > Add a flag that allows them to mark their export operations accordingly
> > and make NFS check for its presence.
> >
> > @Amir, I'll reorder the patches such that this series comes prior to the
> > pidfs file handle series. Doing it that way will mean that there's never
> > a state where pidfs supports file handles while also being exportable.
> > It's probably not a big deal but it's definitely cleaner. It also means
> > the last patch in this series to mark pidfs as non-exportable can be
> > dropped. Instead pidfs export operations will be marked as
> > non-exportable in the patch that they are added in.
>
> Can you please invert the polarity?  Marking something as not supporting
> is always awkward.  Clearly marking it as supporting something (and
> writing down in detail what is required for that) is much better, even
> it might cause a little more churn initially.
>

Churn would be a bit annoying, but I guess it makes sense.
I agree with Christian that it should be done as cleanup to allow for
easier backport.

Please suggest a name for this opt-in flag.
EXPORT_OP_NFS_EXPORT???

Thanks,
Amir.