restructure
diff --git a/Makefile b/Makefile
index 722c0d3..211b8ed 100644
--- a/Makefile
+++ b/Makefile
@@ -3,20 +3,16 @@
 LDFLAGS+=
 
 all: libltp.a
-	@$(MAKE) -C doio $@
 	@$(MAKE) -C tests $@
 	@$(MAKE) -C pan $@
 	@$(MAKE) -C tools $@
-	@$(MAKE) -C ltctests $@
-	@$(MAKE) -C ltctests install
+	@$(MAKE) -C testcases install
 
 libltp.a:
 	@$(MAKE) -C lib $@
 
 clean:
 	@$(MAKE) -C lib $@
-	@$(MAKE) -C doio $@
-	@$(MAKE) -C tests $@
 	@$(MAKE) -C pan $@
 	@$(MAKE) -C tools $@
-	@$(MAKE) -C ltctests $@
+	@$(MAKE) -C testcases $@