[CRIU] [RFC PATCH 7/9] fuse: add fuse device ioctl(FUSE_DEV_IOC_REINIT)

[Aleksandr Mikhalitsyn]

On Fri, Mar 3, 2023 at 8:26 PM Bernd Schubert
<bernd.schubert at fastmail.fm> wrote:
>
>
>
> On 2/20/23 20:37, Alexander Mikhalitsyn wrote:
> > This ioctl aborts fuse connection and then reinitializes it,
> > sends FUSE_INIT request to allow a new userspace daemon
> > to pick up the fuse connection.
> >
> > Cc: Miklos Szeredi <mszeredi at redhat.com>
> > Cc: Al Viro <viro at zeniv.linux.org.uk>
> > Cc: Amir Goldstein <amir73il at gmail.com>
> > Cc: Stéphane Graber <stgraber at ubuntu.com>
> > Cc: Seth Forshee <sforshee at kernel.org>
> > Cc: Christian Brauner <brauner at kernel.org>
> > Cc: Andrei Vagin <avagin at gmail.com>
> > Cc: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
> > Cc: linux-fsdevel at vger.kernel.org
> > Cc: linux-kernel at vger.kernel.org
> > Cc: criu at openvz.org
> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn at canonical.com>
> > ---
> >   fs/fuse/dev.c             | 132 ++++++++++++++++++++++++++++++++++++++
> >   include/uapi/linux/fuse.h |   1 +
> >   2 files changed, 133 insertions(+)
> >
> > diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> > index 737764c2295e..0f53ffd63957 100644
> > --- a/fs/fuse/dev.c
> > +++ b/fs/fuse/dev.c
> > @@ -2187,6 +2187,112 @@ void fuse_abort_conn(struct fuse_conn *fc)
> >   }
> >   EXPORT_SYMBOL_GPL(fuse_abort_conn);
> >
> > +static int fuse_reinit_conn(struct fuse_conn *fc)
> > +{
> > +     struct fuse_iqueue *fiq = &fc->iq;
> > +     struct fuse_dev *fud;
> > +     unsigned int i;
> > +
> > +     if (fc->conn_gen + 1 < fc->conn_gen)
> > +             return -EOVERFLOW;
> > +
> > +     fuse_abort_conn(fc);
> > +     fuse_wait_aborted(fc);
>
> Shouldn't this also try to flush all data first?

I think we should. Thanks for pointing to that!

I've read all your comments and I'll prepare -v2 series soon.

Thanks a lot, Bernd!

>