Re: [ckrm-tech] [PATCH 7/7] containers (V7): Container interface to nsproxy subsystem

Serge E. Hallyn
2007-04-03T15:41:19Z

Quoting Eric W. Biederman (ebiederm@xmission.com):
> Srivatsa Vaddagiri <vatsa@in.ibm.com> writes:
>
> > On Mon, Apr 02, 2007 at 09:09:39AM -0500, Serge E. Hallyn wrote:
> >> Losing the directory isn't a big deal though. And both unsharing a
> >> namespace (which causes a ns_container_clone) and mounting the hierarchy
> >> are done by userspace, so if for some installation it is a big deal,
> >> the init scripts on initrd can mount the hierarchy before doing any
> >> unsharing.
> >
> > Yes I thought of that after posting this (that initrd can mount the
> > hierarchies), so this should not be an issue in practice ..
> >
> >> Can you think of a reason why losing a few directories matters?
> >
> > If we loose directories, then we don't have a way to manage the
> > task-group it represents thr' the filesystem interface, so I consider
> > that bad. As we agree, this will not be an issue if initrd
> > mounts the ns hierarchy atleast at bootup.
>
> I suspect that could be a problem if we have recursive containers.
> Even by having a separate mount namespace for isolation you really
> don't want to share the mount. If you can see all of the processes
> you do want to be able to see and control everything.

Are you asking about what happens if initrd in a vserver asks to
mount -t container -o ns,cpusets /containers
?

I suppose in that case it would make sense to allow a separate mount
instance with it's own superblock, with s_root pointing to the dentry
for the container the vserver is in?

> I guess I want to ask before this gets to far. Why are all of the
> namespaces lumped into one group? I would think it would make much
> more sense to treat each namespace individually (at least for the
> user space interface).
>
> Eric