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.
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