[lxc-devel] loop mounts and #195

[Stéphane Graber]

On Sat, Aug 22, 2015 at 01:21:59PM +0000, Serge Hallyn wrote:
> Quoting Wolfgang Bumiller (w.bumiller at proxmox.com):
> > We came across lxc's #195 while working on our frontend to support
> > mount entries via lxc.mount.entry.
> > 
> > The issue there (despite the change of the title) seems to be just the
> > `loop' option (which ends up passed to mount(2) as part of the
> > `data').
> > 
> > There's already code for loop devices, and a loop 'bdev' type for a
> > `loop:` prefixed rootfs, so adding support for loop mounts shouldn't
> > be all too hard (I'm willing to work on that.)
> > 
> > I'm also wondering, however, if the use of libmount has been considered
> > before? Admittedly I haven't looked too deeply into it yet, but it's
> > what the mount command uses and so I'd assume it supports all the
> > various options. (Though maybe more than desired due to security
> > concerns?) Let me know if this has already come up (the big search
> > machine hasn't found much ;-P).
> 
> Don't think it's been discussed before.  I wouldn't be opposed.  We
> have a few lxc.mount.entry options like 'create=file' which we'd need
> to filter out, but that's ok.  I've not looked at the api enough to
> know whether it would simplify or complicate our code.  The mount
> calls themselves are pretty simple.  Does libmount automatically handle
> things like readonly bind mounts?

So I have my usual concern about availability on Android and other
embedded platforms (openwrt and the like) too.

If we can make using libmount an opt-in thing (when available), then
it'd be fine I guess. I just want to keep the number of hard external
dependencies reasonably low.

-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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