+#define ZB_IS_ZERO(zb) \
+ ((zb)->zb_objset == 0 && (zb)->zb_object == 0 && \
+ (zb)->zb_level == 0 && (zb)->zb_blkid == 0)
+#define ZB_IS_ROOT(zb) \
+ ((zb)->zb_object == ZB_ROOT_OBJECT && \
+ (zb)->zb_level == ZB_ROOT_LEVEL && \
+ (zb)->zb_blkid == ZB_ROOT_BLKID)
+