[Virtio-fs] [PATCH][v2] fuse, virtiofs: Do not alloc/install fuse device in fuse_fill_super_common()

[Miklos Szeredi]

On Mon, May 4, 2020 at 8:33 PM Vivek Goyal <vgoyal at redhat.com> wrote:
>

> Subject: virtiofs: Do not use fuse_fill_super_common() for fuse device installation
>
> fuse_fill_super_common() allocates and installs one fuse_device. Hence
> virtiofs allocates and install all fuse devices by itself except one.
>
> This makes logic little twisted. There does not seem to be any real need
> that why virtiofs can't allocate and install all fuse devices itself.
>
> So opt out of fuse device allocation and installation while calling
> fuse_fill_super_common().
>
> Regular fuse still wants fuse_fill_super_common() to install fuse_device.
> It needs to prevent against races where two mounters are trying to mount
> fuse using same fd. In that case one will succeed while other will get
> -EINVAL.
>
> virtiofs does not have this issue because sget_fc() resolves the race
> w.r.t multiple mounters and only one instance of virtio_fs_fill_super()
> should be in progress for same filesystem.

Thanks, applied.

Miklos