Re: [PATCH 0/4] Add the ability to query mount options in statmount

[Josef Bacik <josef@toxicpanda.com>]

On Tue, Jun 25, 2024 at 03:52:03PM +0200, Karel Zak wrote:
> On Tue, Jun 25, 2024 at 03:35:17PM GMT, Christian Brauner wrote:
> > On Tue, Jun 25, 2024 at 03:04:40PM GMT, Miklos Szeredi wrote:
> > > On Tue, 25 Jun 2024 at 15:00, Josef Bacik <josef@toxicpanda.com> wrote:
> > > 
> > > > We could go this way I suppose, but again this is a lot of work, and honestly I
> > > > just want to log mount options into some database so I can go looking for people
> > > > doing weird shit on my giant fleet of machines/containers.  Would the iter thing
> > > > make the overlayfs thing better?  Yeah for sure.  Do we care?  I don't think so,
> > > > we just want all the options, and we can all strsep/strtok with a comma.
> > > 
> > > I think we can live with the monolithic option block.  However I'd
> > > prefer the separator to be a null character, thus the options could be
> > > sent unescaped.  That way the iterator will be a lot simpler to
> > > implement.
> > 
> > For libmount it means writing a new parser and Karel prefers the ","
> > format so I would like to keep the current format.
>  
> Sorry for the misunderstanding. I had a chat with Christian about it
> when I was out of my office (and phone chats are not ideal for this).
> 
> I thought Miklos had suggested using a space (" ") as the separator, but
> after reading the entire email thread, I now understand that Miklos'
> suggestion is to use \0 (zero) as the options separator.
> 
> I have no issue with using \0, as it will make things much simpler.

What I mean was "we can all strsep/strtok with a comma" I meant was in
userspace.  statmount() gives you the giant block, it's up to user space to
parse it.

I can change the kernel to do this for you, and then add a mnt_opts_len field so
you know how big of a block you get.

But that means getting the buffer, and going back through it and replacing every
',' with a '\0', because I'm sure as hell not going and changing all of our
->show_options() callbacks to not put in a ','.

Is this the direction we want to go?  Thanks,

Josef