use tree-specific IO opcallbacks
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java
index 8b489a6..b924024 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrimaryIndexOperationTracker.java
@@ -89,7 +89,7 @@
             for (ILSMIndex lsmIndex : indexes) {
                 ILSMIndexAccessor accessor = (ILSMIndexAccessor) lsmIndex.createAccessor(
                         NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-                accessor.scheduleFlush(ioOpCallback);
+                accessor.scheduleFlush(((BaseOperationTracker) lsmIndex.getOperationTracker()).getIOOperationCallback());
             }
 
         }