.

wcfs/client/wcfs.cpp

@@ -511,7 +511,6 @@ error _Conn::resync(zodb::Tid at) {
 
     // set new wconn.at early, so that e.g. Conn.open running simultaneously
     // to second part of resync (see below) uses new at.
-    // XXX no need since wconn._filehMu is locked? -> no - it is *needed* after wconn.filehMu became RWMutex
     wconn.at = at;
 
     // go through all files opened under wconn and pre-adjust their mappings
@@ -698,6 +697,8 @@ retry:
     });
     wconn._filehMu.Unlock();
 
+    // do the actuall open.
+    // We hold only wconn.atMu.R, but not wconn.filehMu, nor f.mu .
     f->_openErr = f->_open();
     if (f->_openErr != nil)
         return make_pair(nil, E(f->_openErr));