1 files changed, 7 insertions, 0 deletions
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 8fa011654a..ceec8c2f56 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -419,9 +419,16 @@ struct BlockDriver {
     /*
      * Returns 1 if newly created images are guaranteed to contain only
      * zeros, 0 otherwise.
+     * Must return 0 if .bdrv_has_zero_init_truncate() returns 0.
      */
     int (*bdrv_has_zero_init)(BlockDriverState *bs);
 
+    /*
+     * Returns 1 if new areas added by growing the image with
+     * PREALLOC_MODE_OFF contain only zeros, 0 otherwise.
+     */
+    int (*bdrv_has_zero_init_truncate)(BlockDriverState *bs);
+
     /* Remove fd handlers, timers, and other event loop callbacks so the event
      * loop is no longer in use.  Called with no in-flight requests and in
      * depth-first traversal order with parents before child nodes.