mds: fix crash while stopping rank

trim() was broken in:
8a91daae mds: fix mds crash when mds_max_log_events smaller

When doing a final trim in shutdown we need to trim everything,
not just all but the last segment.  The previous change's intent
was to prevent badness when mds_log_max_events was too small: accomplish
the same thing here by clamping the value to something sane.

Fixes: #12355
Signed-off-by: John Spray <john.spray@redhat.com>

diff --git a/src/mds/MDLog.cc b/src/mds/MDLog.cc
index 2e58369929e17ffae540fbd07a78de14a6397a2c..63bc864647c8cd4314a0a03329cacb55be493f89 100644 (file)
--- a/src/mds/MDLog.cc
+++ b/src/mds/MDLog.cc
@@ -552,6 +552,11 @@ void MDLog::trim(int m)
     return;
   }
 
+  // Clamp max_events to not be smaller than events per segment
+  if (max_events > 0 && max_events <= g_conf->mds_log_events_per_segment) {
+    max_events = g_conf->mds_log_events_per_segment + 1;
+  }
+
   submit_mutex.Lock();
 
   // trim!
@@ -572,7 +577,7 @@ void MDLog::trim(int m)
   stop += 2.0;
 
   map<uint64_t,LogSegment*>::iterator p = segments.begin();
-  while (segments.size() > 1 && p != segments.end() &&
+  while (p != segments.end() &&
         ((max_events >= 0 &&
           num_events - expiring_events - expired_events > max_events) ||
          (segments.size() - expiring_segments.size() - expired_segments.size() > max_segments))) {