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Message-ID: <381a19bb-d17e-b48b-8259-6287dbe170df@fastmail.fm>
Date:   Fri, 3 Mar 2023 20:26:52 +0100
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Subject: Re: [RFC PATCH 7/9] fuse: add fuse device ioctl(FUSE_DEV_IOC_REINIT)
Content-Language: en-US
To:     Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>,
        mszeredi@redhat.com
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Amir Goldstein <amir73il@gmail.com>,
        =?UTF-8?Q?St=c3=a9phane_Graber?= <stgraber@ubuntu.com>,
        Seth Forshee <sforshee@kernel.org>,
        Christian Brauner <brauner@kernel.org>,
        Andrei Vagin <avagin@gmail.com>,
        Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        criu@openvz.org
References: <20230220193754.470330-1-aleksandr.mikhalitsyn@canonical.com>
 <20230220193754.470330-8-aleksandr.mikhalitsyn@canonical.com>
From:   Bernd Schubert <bernd.schubert@fastmail.fm>
In-Reply-To: <20230220193754.470330-8-aleksandr.mikhalitsyn@canonical.com>
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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@redhat.com>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Amir Goldstein <amir73il@gmail.com>
> Cc: StÃ©phane Graber <stgraber@ubuntu.com>
> Cc: Seth Forshee <sforshee@kernel.org>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Andrei Vagin <avagin@gmail.com>
> Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: criu@openvz.org
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@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?