drivers/char/ftape/lowlevel/ftape-buffer.c should #include "../lowlevel/ftape-buffer.h"

Every file should #include the headers containing the prototypes for
it's global functions.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

drivers/char/ftape/lowlevel/ftape-buffer.c

@@ -33,6 +33,7 @@
 #include "../lowlevel/ftape-rw.h"
 #include "../lowlevel/ftape-read.h"
 #include "../lowlevel/ftape-tracing.h"
+#include "../lowlevel/ftape-buffer.h"
 
 /*  DMA'able memory allocation stuff.
  */