Re: [PATCH RFC v2] fhandle: expose u64 mount id to name_to_handle_at(2)

[Miklos Szeredi]

On Tue, 28 May 2024 at 15:24, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> On Tue, May 28, 2024 at 02:04:16PM +0200, Christian Brauner wrote:
> > Can you please explain how opening an fd based on a handle returned from
> > name_to_handle_at() and not using a mount file descriptor for
> > open_by_handle_at() would work?
>
> Same as NFS file handles:
>
> name_to_handle_at returns a handle that includes a file system
> identifier.
>
> open_by_handle_at looks up the superblock based on that identifier.

The open file needs a specific mount, holding the superblock is not sufficient.

Thanks,
Miklos