[Devel] Re: [RFC] [PATCH 0/3] containers: introduction

[Eric W. Biederman]

"Serge E. Hallyn" <serue at us.ibm.com> writes:

> Quoting Eric W. Biederman (ebiederm at xmission.com):
>> "Serge E. Hallyn" <serue at us.ibm.com> writes:
>> 
>> > Or we could go ahead and fully implement it in procfs.  As you'd said
>> > earlier, that really maps best into what we want.  Containerfs was
>> > just much simpler and quicker to implement for demonstrating the semantics.
>> 
>> Well for what it is worth I just notices that nfs is currently and automounter
>> that transparently unmounts it's children when you unmount it.  I don't think
>> that is quite enough to split /proc into two but it does have some potential
>> when it comes to new features.
>> 
>> Using itty bity purpose built file systems if there is an automounter for them
>> because much easier for user space.
>
> I'm not parsing the last sentence.
>
> Are you suggesting that we may be able to stick with a custom fs,
> using autofs to automount it if the symlink /proc/$$/container is
> dereferenced while only a kernel mount of /containers exists?
>
> I suppose a simpler solution is to not define /proc/$$/container,
> but rather just let /container in the containerfs symlink to
> the current process' container.  That way you can't reference
> /containers/container unless containerfs is already mounted under
> /containers, and we avoid the problem completely.

I am saying:
autofs is not special.  Doing automounting the nfs way
you can add and remove mounts transparently to the user.  

A very good use for this would be to mount/unmount things like
/proc/sys/fs/binfmt_misc/.

That technique may have an implication for the design of a container
filesystem.

The result is that if something is more simply implemented as a
separate filesystem, that is a possibility.

Eric
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