<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Aug 6, 2015 at 6:50 AM, Filipe Brandenburger <span dir="ltr"><<a href="mailto:filbranden@google.com" target="_blank">filbranden@google.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On Thu, Aug 6, 2015 at 2:14 AM, Pavel Emelyanov <<a href="mailto:xemul@parallels.com">xemul@parallels.com</a>> wrote:<br>
> On 08/06/2015 02:21 AM, Gabriel Guimaraes wrote:<br>
>> So I just tested it and it turns out that, because of the Kernel bug, statfs returns ext2/ext3 instead<br>
>> of OVERLAYFS_MAGIC when used on a symlink to a file in an OVFs directory, so we can't rely on that.<br>
><br>
> I see :) Yet another patch idea for the kernel.<br>
<br>
</span>Not really though...<br>
<br>
As of kernel 4.2-rc2, all the kernel overlayfs bugs are fixed (in<br>
particular the ones fixing the paths of the symlinks under<br>
/proc/*/fd/*), so on that kernel version criu without this patchset<br>
works to checkpoint/restore containers using overlayfs.<br>
<br>
This patch is meant to work around the bugs present in 3.18ish up to<br>
4.2 when the issue has been resolved.<br>
<br>
If we could go back in time to have a kernel patch applied, we should<br>
instead apply the patchset that actually fixed the issue in 4.2 :-)<br>
<br>
The patches that fixed the overlayfs issues are listed here:<br>
<a href="http://criu.org/Docker#OverlayFS" rel="noreferrer" target="_blank">http://criu.org/Docker#OverlayFS</a> and I believe Ubuntu Vivid might get<br>
these backports into their 3.19.<br>
<br>
Gabriel's code will work properly on both the kernel with and without the fixes.<br>
<br>
Not sure if this was clear from the original submission... Perhaps in<br>
light of these facts you'd like to have some comments or commit<br>
descriptions rephrased to indicate that this code is there to support<br>
kernels in that version range?<br>
<br>
Cheers!<br>
<span class="HOEnZb"><font color="#888888">Filipe<br></font></span></blockquote><div><br></div><div>To be completely clear:</div><div><br></div><div>1. The good news is that the OverlayFS bugs will be fixed in the next Ubuntu Vivid kernel because I filed a bug and Chris Arges of Canonical reproduced the problem and also verified that the patches I had mentioned fix the issues. For details please see: <a href="https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1479468">https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1479468</a></div><div><br></div><div>2. In the meantime, Ubuntu Vivid users can install a 3.19 kernel with OvelayFS bugs fixed from CRIU PPA: <a href="https://launchpad.net/~criu/+archive/ubuntu/ppa">https://launchpad.net/~criu/+archive/ubuntu/ppa</a></div><div><br></div><div>3. Users of other distros, however, will continue to have this bug until they upgrade their kernel to 4.2 or back port the patches.</div><div><br></div><div>--Saied</div><div><br></div></div></div></div>