Merge pull request ceph#64043 from Naveenaidu/wip-71718-tentacle

tentacle: osd/PeeringState: handle race condition of DeferBackfill event for Backfilling state

Author: Naveenaidu

src/osd/PeeringState.cc

@@ -5411,13 +5411,12 @@ boost::statechart::result
 PeeringState::Backfilling::react(const DeferBackfill &c)
 {
   DECLARE_LOCALS;
-
-  psdout(10) << "defer backfill, retry delay " << c.delay << dendl;
-  ps->state_set(PG_STATE_BACKFILL_WAIT);
-  ps->state_clear(PG_STATE_BACKFILLING);
-  suspend_backfill();
-
   if (ps->needs_backfill()) {
+    psdout(10) << "defer backfill, retry delay " << c.delay << dendl;
+    ps->state_set(PG_STATE_BACKFILL_WAIT);
+    ps->state_clear(PG_STATE_BACKFILLING);
+    suspend_backfill();
+
     pl->schedule_event_after(
       std::make_shared<PGPeeringEvent>(
 	ps->get_osdmap_epoch(),
@@ -5427,6 +5426,9 @@ PeeringState::Backfilling::react(const DeferBackfill &c)
     return transit<NotBackfilling>();
   } else {
     // raced with MOSDPGBackfill::OP_BACKFILL_FINISH, ignore
+    psdout(10) << "discarding stale DeferBackfill event , pg does not need "
+		  "backfill anymore"
+	       << dendl;
     return discard_event();
   }
 }