[lxc-users] Using shiftfs with NFS mounted filesystem

[Michael Eager]

On 7/20/20 7:46 PM, Serge E. Hallyn wrote:
> On Mon, Jul 20, 2020 at 09:21:08AM -0700, Michael Eager wrote:
>> On 7/19/20 2:04 PM, Serge E. Hallyn wrote:
>>> On Sun, Jul 19, 2020 at 07:53:08PM +0300, Amir Goldstein wrote:
>>>> On Sun, Jul 19, 2020 at 5:13 PM Serge E. Hallyn <serge at hallyn.com> wrote:
>>>>>
>>>>> On Sun, Jul 19, 2020 at 06:53:03AM -0700, Michael Eager wrote:
>>>>>> On 7/18/20 8:37 PM, Serge E. Hallyn wrote:
>>>>>>> On Sat, Jul 18, 2020 at 11:16:16AM -0700, Michael Eager wrote:
>>>>>>>> I'm running LXD on a Centos 8 host, kernel-4.18.0.  I built and installed
>>>>>>>> the shiftfs module.
>>>>>>>
>>>>>>>    From what source?
>>>>>>
>>>>>> https://github.com/toby63/shiftfs-dkms
>>>>>
>>>>> Interesting.  Yeah the shiftfs.c looks identical to what's in
>>>>> ubuntu's, but when I backported that to 4.14 I had to also take
>>>>> a bunch of other patches (https://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux.git/log/?h=v4.14.180-shiftfs)
>>>>> which may or may not be in 4.18.  Still, I don't actually think
>>>>> that's the problem.  NFS has always been difficult to use
>>>>> with layered filesystems.
>>>>>
>>>>> Amir, as far as you know, does overlay on top of NFS work
>>>>> these days?
>>>>>
>>>>
>>>> I know people are using it, but only as lower fs, which are files that
>>>> are not expected to be changed.
>>>> NFS is not supported as upper fs.
>>>
>>> Thanks Amir.  I over-snipped, but Michael is having problems
>>> when NFS is the underlay for shiftfs.  If overlay works fine,
>>> then that's an interesting complication :)
>>>
>>> I'm hoping to have some time to try it out soon.
>>>
>>> thanks,
>>> -serge
>>
>> If you would like me to submit a bug report, just tell me where.
> 
> Since it's shipped with the Ubuntu kernel, you could test it in an
> Ubuntu VM and then file it at
> https://bugs.launchpad.net/ubuntu/+source/linux/+filebug  I don't
> have any better place to suggest tracking it.

I'm running LXD on CentOS 8, kernel-4.18.0.  I built the shiftfs module 
from https://github.com/toby63/shiftfs-dkms.

I can submit an issue on GitHub or bugzilla.kernel.org.  Setting up a 
Ubunut VM with LXD seems like a bit of work.