osd/PeeringState: fix history.same_interval_since of merge target again

The symptom looks much like we see in
	https://tracker.ceph.com/issues/37654.

The root cause is that both merge source and target could be
fabricated PGs (aka placeholders), hence merge target's
same_interval_since could remain 0 after merge.

Fix by adjusting history.same_interval_since to last_epoch_clean
reported by these PGs were found to be ready for merge.
This peer is going to be ignored/purged by primary anyway later
when peering is done.

Fixes: https://tracker.ceph.com/issues/45991
Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
(cherry picked from commit be5ea3a01f31b4893a823e971f452f3ccf9de001)

Conflicts:
	src/osd/PeeringState.cc
- file does not exist in nautilus; made the change manually in PG.cc
  instead

diff --git a/src/osd/PG.cc b/src/osd/PG.cc
index d421fc512302f2315a21ca87a3a0c4b9954d6717..fade231d1c8d7376d5c9d1f2e51a4400f7294357 100644 (file)
--- a/src/osd/PG.cc
+++ b/src/osd/PG.cc
@@ -2909,6 +2909,20 @@ void PG::merge_from(map<spg_t,PGRef>& sources, RecoveryCtx *rctx,
             << sources.begin()->second->info.history
             << dendl;
 
+    // above we have pulled down source's history and we need to check
+    // history.epoch_created again to confirm that source is not a placeholder
+    // too. (peering requires a sane history.same_interval_since value for any
+    // non-newly created pg and below here we know we are basically iterating
+    // back a series of past maps to fake a merge process, hence we need to
+    // fix history.same_interval_since first so that start_peering_interval()
+    // will not complain)
+    if (info.history.epoch_created == 0) {
+      dout(10) << __func__ << " both merge target and source are placeholders,"
+               << " set sis to lec " << info.history.last_epoch_clean
+               << dendl;
+      info.history.same_interval_since = info.history.last_epoch_clean;
+    }
+
     // if the past_intervals start is later than last_epoch_clean, it
     // implies the source repeered again but the target didn't, or
     // that the source became clean in a later epoch than the target.