f2fs: fix endian conversion bugs reported by sparse

This patch should resolve the bugs reported by the sparse tool.
Initial reports were written by "kbuild test robot" managed by fengguang.wu.

In my local machines, I've tested also by running:
> make C=2 CF="-D__CHECK_ENDIAN__"

Accordingly, I've found lots of warnings and bugs related to the endian
conversion. And I've fixed all at this moment.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index 1429ece..c2fbbc3 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -272,8 +272,8 @@
  * ex) data_blkaddr = (block_t)(nodepage_start_address + ofs_in_node)
  */
 #define ENTRIES_IN_SUM		512
-#define	SUMMARY_SIZE		(sizeof(struct f2fs_summary))
-#define	SUM_FOOTER_SIZE		(sizeof(struct summary_footer))
+#define	SUMMARY_SIZE		(7)	/* sizeof(struct summary) */
+#define	SUM_FOOTER_SIZE		(5)	/* sizeof(struct summary_footer) */
 #define SUM_ENTRY_SIZE		(SUMMARY_SIZE * ENTRIES_IN_SUM)
 
 /* a summary entry for a 4KB-sized block in a segment */
@@ -297,7 +297,7 @@
 	__u32 check_sum;		/* summary checksum */
 } __packed;
 
-#define SUM_JOURNAL_SIZE	(PAGE_CACHE_SIZE - SUM_FOOTER_SIZE -\
+#define SUM_JOURNAL_SIZE	(F2FS_BLKSIZE - SUM_FOOTER_SIZE -\
 				SUM_ENTRY_SIZE)
 #define NAT_JOURNAL_ENTRIES	((SUM_JOURNAL_SIZE - 2) /\
 				sizeof(struct nat_journal_entry))