mds: add debugging for standby-replay journal positions

This adds debugging for https://tracker.ceph.com/issues/59119

Signed-off-by: Patrick Donnelly <[email protected]>

Author: batrick

src/mds/MDSRank.cc

@@ -1816,7 +1816,11 @@ class MDSRank::C_MDS_StandbyReplayRestartFinish : public MDSIOContext {
 
 void MDSRank::_standby_replay_restart_finish(int r, uint64_t old_read_pos)
 {
-  if (old_read_pos < mdlog->get_journaler()->get_trimmed_pos()) {
+  auto trimmed_pos = mdlog->get_journaler()->get_trimmed_pos();
+  dout(20) << __func__ << ":"
+           << " old_read_pos=" << old_read_pos
+           << " trimmed_pos=" << trimmed_pos << dendl;
+  if (old_read_pos < trimmed_pos) {
     dout(0) << "standby MDS fell behind active MDS journal's expire_pos, restarting" << dendl;
     respawn(); /* we're too far back, and this is easier than
 		  trying to reset everything in the cache, etc */