f2fs: align data types between on-disk and in-memory block addresses

The on-disk block address is defined as __le32, but in-memory block address,
block_t, does as u64.

Let's synchronize them to 32 bits.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/f2fs.h

@@ -37,7 +37,10 @@
 		typecheck(unsigned long long, b) &&			\
 		((long long)((a) - (b)) > 0))
 
-typedef u64 block_t;
+typedef u32 block_t;	/*
+			 * should not change u32, since it is the on-disk block
+			 * address format, __le32.
+			 */
 typedef u32 nid_t;
 
 struct f2fs_mount_info {

include/linux/f2fs_fs.h

@@ -20,8 +20,8 @@
 #define F2FS_BLKSIZE			4096	/* support only 4KB block */
 #define F2FS_MAX_EXTENSION		64	/* # of extension entries */
 
-#define NULL_ADDR		0x0U
-#define NEW_ADDR		-1U
+#define NULL_ADDR		((block_t)0)	/* used as block_t addresses */
+#define NEW_ADDR		((block_t)-1)	/* used as block_t addresses */
 
 #define F2FS_ROOT_INO(sbi)	(sbi->root_ino_num)
 #define F2FS_NODE_INO(sbi)	(sbi->node_ino_num)