Subject: Re: [vserver] Issue with OverlayFS in 3.18
From: Oliver Welter <mail@oliwel.de>
Date: Sun, 22 Feb 2015 15:50:04 +0100
Sun, 22 Feb 2015 15:50:04 +0100
Hi Bertl,

Am 02.02.2015 um 11:11 schrieb Herbert Poetzl:
> On Mon, Feb 02, 2015 at 08:10:15AM +0100, Oliver Welter wrote:
>> Am 02.02.2015 um 01:58 schrieb Herbert Poetzl:
>>> On Sun, Feb 01, 2015 at 03:28:22PM +0100, Oliver Welter wrote:
>
>>>> Trying the same without starting the vserver, using a simple
>>>> "chroot" works, so it looks like some limits are not working
>>>> correctly.
>
>>> Please try without Linux-VServer isolation but with the same
>>> namespace setup, I don't think that you are hitting a limit
>>> here, it looks more like a namespace problem of overlayfs.
>
>> Can you be a bit more verbose - I never git in touch with the
>> individual components ;)
>
> Either use vnamespace or the unshare tool to create a namespace
> setup identical to your guest and check if the issue remains.

I am unable to reproduce it with vnamespace or unshare, I used attached 
test script and ran it as:

vnamespace -n /mnt/test.sh
vcontext --create --xid 42 /mnt/test.sh
unshare  -i -m -u test.sh

with the correct result (file breakme is replaced by a directory on the 
common mount).

When you do the same inside a vserver, it does not work (use overlay to 
assemble rootfs of vserver, start vserver, try to change entity which 
exists on the lower but not on the upper fs).

Any further ideas?

Oli


#!/bin/bash -x

mkdir test test/lower test/root test/upper test/work

echo "Testfile" > test/lower/breakme

/bin/mount -t overlay overlay 
-olowerdir=test/lower,upperdir=test/upper,workdir=test/work test/root

rm test/root/breakme
mkdir test/root/breakme

ls -la test/root/



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