[overlayfs] Fixes against ubuntu-quantal.git#master-next

[Sedat Dilek]

On Mon, Apr 30, 2012 at 3:54 PM, Sedat Dilek <sedat.dilek at googlemail.com> wrote:
> On Mon, Apr 30, 2012 at 2:28 PM, Andy Whitcroft <apw at canonical.com> wrote:
>> On Sat, Apr 28, 2012 at 04:55:13PM +0200, Sedat Dilek wrote:
>>> On Sat, Apr 28, 2012 at 2:49 PM, Sedat Dilek <sedat.dilek at googlemail.com> wrote:
>>> > On Sat, Apr 28, 2012 at 1:59 PM, Sedat Dilek <sedat.dilek at googlemail.com> wrote:
>>> >> Hi,
>>> >>
>>> >> I wanted to play with OverlayFS against Linux-3.4-rc4.
>>> >>
>>> >> As Ubuntu kernel-team has rebased it in ubuntu-quantal.git#master-next.
>>> >> I made my life easy and took this repo as base for my fixes (or trying to fix).
>>
>> The version applied to Ubuntu Precise was a backported version of the
>> upstream v12 branch.  So I suspect much of the issues are coming from
>> that being a backported version.  For Ubuntu Quantal I have reverted
>> what we had and pulled a clean v12 plus the security fix we had on top.
>> I have then applied similar fixes to pull that forward to v3.4-rc4 and
>> it seems to pass very light touch testing here:
>>
>>  http://git.kernel.org/?p=linux/kernel/git/apw/overlayfs.git;a=shortlog;h=refs/heads/overlayfs.v12apw1
>>
>> I am pushing it out for perusal as people are asking me about it.  This
>> includes an updated permissions fix.
>>
>> -apw
>
> [ CC Jordi Pojol ]
>
> Hi Andy,
>
> thanks for updating the OverlayFS-v12 patchset!
>
> Looks like my d_make_root() fix was not complete :-(.
> Reverting mine and using yours helped me to run OverlayFS ***w/o***
> crashes or call-traces.
>
> Patches applied on top of Linux v3.4-rc5:
> 1. 100-overlayfs_v12.patch (OpenWrt)
> 2. my include-fix (should be the same like the one from apw)
> 3. my touch_atime-fix (same as apw has)
> 4. d_make_root-fix from quantal (by apw)
>
> I tested OverlayFS with a modified test06.sh script from Jordi Pojol
> (testcase-script attached, see [2]).
>
> HINT:
> You will need "[PATCH] fs: Increase limit filesystem stacking depth to
> 3" to run it successfully (patch attached).
>
> Without it you will see in dmesg:
> [  476.709418] overlayfs: maximum fs stacking depth exceeded
>
> FYI:
> Depth "2" was defined in "fs: limit filesystem stacking depth" patch
> from Miklos.
> Not sure if I can loosen that a bit (security issue?).
> Jordy told me in private conversation he has dropped that patch completely.
>
> I will re-test with Andy's "overlayfs.v12apw1" GIT branch [3] (pulled
> into Linux v3.4-rc5).
>
> Hope this helps other users and developers.
>
> - Sedat -
>
> [1] https://dev.openwrt.org/browser/trunk/target/linux/generic/patches-3.3/100-overlayfs_v12.patch
> [2] http://livenet.selfip.com/ftp/debian/overlayfs/test/test06.sh
> [3] http://git.kernel.org/?p=linux/kernel/git/apw/overlayfs.git;a=shortlog;h=refs/heads/overlayfs.v12apw1

As promised I have tested with Andy's patches +  limit-fs-stack-depth=3.
The testcase script runs completely and successfully (all loop and
overlayfs mount-points unmounted properly).

On 1st tests: Looks very good to me :-).

Feedback as tarball attached (kernel-config, dmesg and testcase script
+ results).

Have fun!

- Sedat -
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