f2fs: add f2fs_balance_fs for expand_inode_data

This patch adds f2fs_balance_fs in expand_inode_data to avoid allocation failure
with segment.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 2a91a7d..208f1a9 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -672,6 +672,8 @@
 	loff_t off_start, off_end;
 	int ret = 0;
 
+	f2fs_balance_fs(sbi);
+
 	ret = inode_newsize_ok(inode, (len + offset));
 	if (ret)
 		return ret;