Re: [RFC 1/1] shiftfs: uid/gid shifting bind mount

[Djalal Harouni]

On Wed, Feb 15, 2017 at 10:37 AM, Eric W. Biederman
<ebiederm@xxxxxxxxxxxx> wrote:
> Djalal Harouni <tixxdz@xxxxxxxxx> writes:
>
>> On Mon, Feb 13, 2017 at 11:15 AM, Eric W. Biederman
>> <ebiederm@xxxxxxxxxxxx> wrote:
>>> James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> writes:
>
>>>> So is this.  Basically anything that begins by mounting gets a super
>>>> block and can use the s_user_ns to map from the filesystem view to the
>>>> kernel view of ids.  Apart from greater sophistication in the
>>>> parametrisation, it sounds like we have all the machinery you need.
>>>>  I'm sure the containers people will consider reasonable patches to
>>>> change this.
>>>
>>> Yes.
>>>
>>> And to be clear we have all of that merged now and mostly present and
>>> hooked up in all filesystems without any shiftfs like changes needed.
>>>
>>> To use this with a filesystem a last pass needs to be had to verify that
>>> the cases where something does not map are handled cleanly.
>>
>> Still this does not answer the question how to dynamically
>> *attach/share* data or read-only volumes as defined by
>> orchestration/container tools into several containers. Am I missing
>> something or is the plan to have per superblock mount for each one ?
>
> Agreed.  That is a related problem and the problem that shiftfs
> is working to solve.
>
> If you only need a single mapping the infrastructure is basically done
> in the kernel today.  If you need multiple mappings we need something
> more.

Yes, I'm asking since there is that vfs+userns proposed approach that
I linked in this thread, that deals with this particular problem: in
which mount namespace<->container the volume appears, maybe that can
be used on top of the s_user_ns ...

Thanks!


-- 
tixxdz