[Gluster-devel] regressions due to 64-bit ext4 directory cookies

Anand Avati anand.avati at gmail.com
Thu Mar 28 22:20:59 UTC 2013


On Thu, Mar 28, 2013 at 3:14 PM, Anand Avati <anand.avati at gmail.com> wrote:

> On Thu, Mar 28, 2013 at 12:43 PM, Jeff Darcy <jdarcy at redhat.com> wrote:
>
>> On 03/28/2013 02:49 PM, Anand Avati wrote:
>> > Yes, it should, based on the theory of how ext4 was generating the
>> > 63bits. But Jeff's test finds that the experiment is not matching the
>> > theory.
>>
>> FWIW, I was able to re-run my test in between stuff related to That
>> Other Problem.  What seems to be happening is that we read correctly
>> until just after d_off 0x4000000000000000, then we suddenly wrap around
>> - not to the very first d_off we saw, but to a pretty early one (e.g.
>> 0x0041b6340689a32e).  This is all on a single brick, BTW, so it's pretty
>> easy to line up the back-end and front-end d_off values which match
>> perfectly up to this point.
>>
>> I haven't had a chance to ponder what this all means and debug it
>> further.  Hopefully I'll be able to do so soon, but I figured I'd
>> mention it in case something about those numbers rang a bell.
>>
>
> Of course, the unit tests (with artificial offsets) were done with brick
> count >= 2. You have tested with DHT subvol count=1, which was not tested,
> and sure enough, the code isn't handling it well. Just verified with the
> unit tests that brick count = 1 condition fails to return the same d_off.
>
> Posting a fixed version. Thanks for the catch!
>

Posted an updated version http://review.gluster.org/4711. This passes unit
tests for all brick counts (>= 1). Can you confirm if the "loop"ing is now
gone in your test env?

Thanks,
Avati
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