f2fs: send REQ_META or REQ_PRIO when reading meta area

Let's send REQ_META or REQ_PRIO when reading meta area such as NAT/SIT
etc.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index eae8dc3..7fe69ff 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -61,7 +61,7 @@
 	if (PageUptodate(page))
 		goto out;
 
-	if (f2fs_readpage(sbi, page, index, READ_SYNC))
+	if (f2fs_readpage(sbi, page, index, READ_SYNC | REQ_META | REQ_PRIO))
 		goto repeat;
 
 	lock_page(page);