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

[Bernd Schubert]

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@xxxxxxxxxx>
> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: Amir Goldstein <amir73il@xxxxxxxxx>
> Cc: Stéphane Graber <stgraber@xxxxxxxxxx>
> Cc: Seth Forshee <sforshee@xxxxxxxxxx>
> Cc: Christian Brauner <brauner@xxxxxxxxxx>
> Cc: Andrei Vagin <avagin@xxxxxxxxx>
> Cc: Pavel Tikhomirov <ptikhomirov@xxxxxxxxxxxxx>
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: criu@xxxxxxxxxx
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
> ---
>   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?