--- reiserfsprogs-3.6.13/lib/misc.c.blkgetsiz64	2004-05-18 16:50:47.000000000 +0200
+++ reiserfsprogs-3.6.13/lib/misc.c	2004-05-18 16:53:19.000000000 +0200
@@ -463,7 +463,13 @@
 }
 
 #if defined(__linux__) && defined(_IOR) && !defined(BLKGETSIZE64)
-#   define BLKGETSIZE64 _IOR(0x12, 114, __u64)
+/* Note! Despite this call being called with *64, it must be encoded to
+ * return only sizeof(size_t), since in earlier kernel versions it was
+ * declared _IOR(0x12, 114, sizeof(u64)), making it use sizeof(sizeof(u64)).
+ *
+ * However, the call itself does always return 64bit!
+ */
+#   define BLKGETSIZE64 _IOR(0x12, 114, size_t)
 #endif
 
 /* To not have problem with last sectors on the block device when switching