osd/PGLog: trim - avoid dereferencing invalid iter

Log(e.g., projected_log) could theoretically be emtpy and hence there might
be potential access violation.

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>

diff --git a/src/osd/PGLog.cc b/src/osd/PGLog.cc
index eb88dc1db3c52fc44557952dffbfdab108c9f6e2..0d9d73e598058b0b4c0c7eed23f9f8e981ea7c9c 100644 (file)
--- a/src/osd/PGLog.cc
+++ b/src/osd/PGLog.cc
@@ -100,9 +100,13 @@ void PGLog::IndexedLog::trim(
 
     // reset complete_to to the beginning of the log
     if (reset_complete_to) {
-      lgeneric_subdout(cct, osd, 20) << " moving complete_to " << " to "
-                      << log.begin()->version << dendl;
       complete_to = log.begin();
+      if (complete_to != log.end()) {
+        lgeneric_subdout(cct, osd, 20) << " moving complete_to to "
+                                       << log.begin()->version << dendl;
+      } else {
+        lgeneric_subdout(cct, osd, 20) << " log is now empty" << dendl;
+      }
     }
   }