don't sum invalid posix counters

darshan-runtime/lib/darshan-posix.c

@@ -1435,6 +1435,8 @@ static void posix_record_reduction_op(void* infile_v, void* inoutfile_v,
         for(j=POSIX_OPENS; j<=POSIX_FDSYNCS; j++)
         {
             tmp_file.counters[j] = infile->counters[j] + inoutfile->counters[j];
+            if(tmp_file.counters[j] < 0) /* make sure invalid counters are -1 exactly */
+                tmp_file.counters[j] = -1;
         }
 
         tmp_file.counters[POSIX_MODE] = infile->counters[POSIX_MODE];

darshan-util/darshan-posix-logutils.c

@@ -387,6 +387,8 @@ static void darshan_log_agg_posix_files(void *rec, void *agg_rec, int init_flag)
             case POSIX_SIZE_WRITE_1G_PLUS:
                 /* sum */
                 agg_psx_rec->counters[i] += psx_rec->counters[i];
+                if(agg_psx_rec->counters[i] < 0) /* make sure invalid counters are -1 exactly */
+                    agg_psx_rec->counters[i] = -1;
                 break;
             case POSIX_MODE:
             case POSIX_MEM_ALIGNMENT: