Hi Sam,
I took a look at calc_acting and I can't figure out enough to create a bug report. There are checks based on last_update and tail but it is difficult go infer how it relates to the rewind_divergent_log function. If you can connect the dots for me I'd be happy to write down a proper bug report ;-)
Cheers
On 06/11/2013 01:02 AM, Samuel Just wrote:
> I think that case may be possible, and that the assert may be wrong.
> We have probably never seen a problem there due to
> osd_min_pg_log_entries. It's also possible that there is a subtle bug
> between there and calc_acting().
> -Sam
>
> On Sat, Jun 8, 2013 at 1:16 AM, Loic Dachary <loic@xxxxxxxxxxx> wrote:
>> [Note: ceph-devel cc'ed]
>>
>> Hi Sam,
>>
>> While trying to create the conditions for the following to happen in PGLog::rewind_divergent_log:
>>
>> if (p == log.log.begin()) {
>> // yikes, the whole thing is divergent!
>> divergent.swap(log.log);
>> break;
>> }
>>
>> https://github.com/ceph/ceph/blob/master/src/osd/PGLog.cc#L355
>>
>> I created this ( matching the drawing attached ), and the test case works.
>>
>> {
>> pg_log_entry_t e;
>>
>> info.log_tail = log.tail = eversion_t(1, 1);
>> newhead = eversion_t(1, 3);
>> e.version = divergent_version = eversion_t(1, 5);
>> e.soid.hash = 0x9;
>> divergent_object = e.soid;
>> e.op = pg_log_entry_t::DELETE;
>> e.prior_version = prior_version = eversion_t(0, 2);
>> log.log.push_back(e);
>> log.head = e.version;
>> }
>>
>> https://github.com/dachary/ceph/commit/d592d7f10968c56139cb470a4111ddfbe08a4030#L0R136
>>
>> But it does not look like a situation that is actually going to happen. I feel something is missing and a hint would be much appreciated :-)
>>
>> Cheers
>>
>> --
>> Loïc Dachary, Artisan Logiciel Libre
>> All that is necessary for the triumph of evil is that good people do nothing.
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Loïc Dachary, Artisan Logiciel Libre
All that is necessary for the triumph of evil is that good people do nothing.
Attachment:
signature.asc
Description: OpenPGP digital signature
