f2fs: relocate f2fs_precache_extents() in f2fs_swap_activate()

This patch exchangs position of f2fs_precache_extents() and
filemap_fdatawrite(), so that f2fs_precache_extents() can load
extent info after physical addresses of all data are fixed.
Signed-off-by: Chao Yu <chao@kernel.org>
Reviewed-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -4045,12 +4045,12 @@ static int f2fs_swap_activate(struct swap_info_struct *sis, struct file *file,
 	if (!f2fs_disable_compressed_file(inode))
 		return -EINVAL;
 
-	f2fs_precache_extents(inode);
-
 	ret = filemap_fdatawrite(inode->i_mapping);
 	if (ret < 0)
 		return ret;
 
+	f2fs_precache_extents(inode);
+
 	ret = check_swap_activate(sis, file, span);
 	if (ret < 0)
 		return ret;