Re: [PATCH] fuse: Apply flags2 only when userspace set the FUSE_INIT_EXT flag

[Vivek Goyal <vgoyal@redhat.com>]

On Tue, Apr 26, 2022 at 03:13:50PM +0200, Miklos Szeredi wrote:
> On Tue, 26 Apr 2022 at 15:01, Vivek Goyal <vgoyal@redhat.com> wrote:
> 
> > Agree that it probably is a nice change if we had introduced this in the
> > beginning itself. Its like extra saftey net. But now if we add it, it
> > will break things which is not nice. So at this point of time, it probably
> > is better to fix fuse servers instead and set ->flags2 to zero, IMHO.
> 
> I think the question is whether the "unfixed" virtiofsd
> implementations made it into any sort of release or not.

Existing unfixed versions are already released in various releses. C version
of virtiofsd is already being used in RHEL8 release and some fedora releases.
And rust version of virtiofsd is supposed to be in RHEL9 beta.

Hence if we change it now, it is possible older virtiofsd (unfixed one)
is running on host and trying to boot a newer guest kernel and that
leads to breaking things.

Thanks
Vivek

> 
> If not, then I think it's fine to break unreleased versions, since
> they are ephemeral anyway.

> 
> Thanks,
> Miklos
>