linux-kernel - Re: [PATCH 00/24] vfs: require filesystems to explicitly opt-in to lease support

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Message-Id: <5a1730f3-30ff-403c-a460-09a81f9616c5@app.fastmail.com>
Date: Wed, 14 Jan 2026 09:52:34 -0500
From: "Chuck Lever" <cel@...nel.org>
To: "Amir Goldstein" <amir73il@...il.com>, "Jeff Layton" <jlayton@...nel.org>
Cc: "Christoph Hellwig" <hch@...radead.org>,
 "Christian Brauner" <brauner@...nel.org>,
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Subject: Re: [PATCH 00/24] vfs: require filesystems to explicitly opt-in to lease
 support



On Wed, Jan 14, 2026, at 9:14 AM, Amir Goldstein wrote:
> On Wed, Jan 14, 2026 at 2:41 PM Jeff Layton <jlayton@...nel.org> wrote:

> Very well then.
> How about EXPORT_OP_PERSISTENT_HANDLES?
>
> This terminology is from the NFS protocol spec and it is also used
> to describe the same trait in SMB protocol.
>
>> The problem there is that we very much do want to keep tmpfs
>> exportable, but it doesn't have stable handles (per-se).
>
> Thinking out loud -
> It would be misguided to declare tmpfs as
> EXPORT_OP_PERSISTENT_HANDLES
> and regressing exports of tmpfs will surely not go unnoticed.
>
> How about adding an exportfs option "persistent_handles",
> use it as default IFF neither options fsid=, uuid= are used,
> so that at least when exporting tmpfs, exportfs -v will show
> "no_persistent_handles" explicitly?

I think we need to be careful. tmpfs filehandles align quite
well with the traditional definition of persistent filehandles.
tmpfs filehandles live as long as tmpfs files do, and that is
all that is required to be considered "persistent".


-- 
Chuck Lever