[Virtio-fs] [PATCH] virtiofs: Export filesystem tags through sysfs

[Vivek Goyal]

On Mon, Oct 09, 2023 at 11:53:42AM +0200, Miklos Szeredi wrote:
> On Thu, 5 Oct 2023 at 22:30, Vivek Goyal <vgoyal at redhat.com> wrote:
> >
> > virtiofs filesystem is mounted using a "tag" which is exported by the
> > virtiofs device. virtiofs driver knows about all the available tags but
> > these are not exported to user space.
> >
> > People have asked these tags to be exported to user space. Most recently
> > Lennart Poettering has asked for it as he wants to scan the tags and mount
> > virtiofs automatically in certain cases.
> >
> > https://gitlab.com/virtio-fs/virtiofsd/-/issues/128
> >
> > This patch exports tags through sysfs. One tag is associated with each
> > virtiofs device. A new "tag" file appears under virtiofs device dir.
> > Actual filesystem tag can be obtained by reading this "tag" file.
> >
> > For example, if a virtiofs device exports tag "myfs", a new file "tag"
> > will show up here.
> >
> > /sys/bus/virtio/devices/virtio<N>/tag
> >
> > # cat /sys/bus/virtio/devices/virtio<N>/tag
> > myfs
> >
> > Signed-off-by: Vivek Goyal <vgoyal at redhat.com>
> 
> Hi Vivek,
> 
> This needs something under Documentation/.

Hi Miklos,

Hmm.., I can easily update the virtiofs documentation.

Initially I was thinking to put something in Documentation/ABI/testing/
as well. But I don't see any virtio related. In fact can't find any
files related to "virtio" at all.

So I will just update the Documentation/filesystems/virtiofs.rst for now.

> 
> While the interface looks good to me, I think we need an ack on that
> from the virtio maintainer.

I am assuming Stefan should be able to provide an ACK. But I will also
add Michael and Paolo in the V2 of the patch and hoping we should be
able to get atleast 1 ACK.

Thanks
Vivek