util: use glibc macros to generate device numbers in the dev_t format

Our version of macroses are worng.

Our macros:
#define MINOR(dev)           ((dev) & 0xff)

Glibc function:
return (__dev & 0xff) | ((unsigned int) (__dev >> 12) & ~0xff);
Reported-by: Amey Deshpande <ameyd@google.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/aarch64/include/asm/types.h

@@ -13,9 +13,6 @@
 #define SIGMAX			64
 #define SIGMAX_OLD		31
 
-#define MAJOR(dev)		((dev)>>8)
-#define MINOR(dev)		((dev) & 0xff)
-
 typedef void rt_signalfn_t(int, siginfo_t *, void *);
 typedef rt_signalfn_t *rt_sighandler_t;
 

include/util.h

@@ -211,11 +211,8 @@ static inline dev_t kdev_to_odev(u32 kdev)
 	 */
 	unsigned major = kdev_major(kdev);
 	unsigned minor = kdev_minor(kdev);
-#if BITS_PER_LONG == 32
-	return (major << 8) | minor;
-#else
-	return (minor & 0xff) | (major << 8) | ((minor & ~0xff) << 12);
-#endif
+
+	return makedev(major, minor);
 }
 
 extern int copy_file(int fd_in, int fd_out, size_t bytes);

mount.c

@@ -158,7 +158,7 @@ dev_t phys_stat_resolve_dev(struct mount_info *tree,
 	 * obtained from mountinfo (ie subvolume0).
 	 */
 	return strcmp(m->fstype->name, "btrfs") ?
-		MKKDEV(MAJOR(st_dev), MINOR(st_dev)) : m->s_dev;
+		MKKDEV(major(st_dev), minor(st_dev)) : m->s_dev;
 }
 
 bool phys_stat_dev_match(struct mount_info *tree, dev_t st_dev,