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Date: Sat, 11 Nov 2023 06:52:36 -0500
From: Greg KH <gregkh@linuxfoundation.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>, linux-fsdevel@vger.kernel.org,
	virtio-fs@redhat.com, mzxreary@0pointer.de, stefanha@redhat.com
Subject: Re: [Virtio-fs] [PATCH] virtiofs: Export filesystem tags through
 sysfs
Message-ID: <2023111104-iron-colossal-960f@gregkh>
References: <20231005203030.223489-1-vgoyal@redhat.com>
 <CAJfpegspVnkXAa5xfvjEQ9r5__vXpcgR4qubdG8=p=aiS2goRg@mail.gmail.com>
 <ZSRg2uiBNmY4mKHr@redhat.com>
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In-Reply-To: <ZSRg2uiBNmY4mKHr@redhat.com>

On Mon, Oct 09, 2023 at 04:21:46PM -0400, Vivek Goyal wrote:
> On Mon, Oct 09, 2023 at 11:53:42AM +0200, Miklos Szeredi wrote:
> > On Thu, 5 Oct 2023 at 22:30, Vivek Goyal <vgoyal@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@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.

No, please put it in Documentation/ABI/ that is where sysfs file
information goes, and where our tools actually look for it (and test for
it!)

thanks,

greg k-h