f2fs crypto: make sure the encryption info is initialized on opendir(2)

This patch syncs f2fs with commit 6bc445e0 ("ext4 crypto: make
sure the encryption info is initialized on opendir(2)") from ext4.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/dir.c

@@ -902,11 +902,19 @@ static int f2fs_readdir(struct file *file, struct dir_context *ctx)
 	return err;
 }
 
+static int f2fs_dir_open(struct inode *inode, struct file *filp)
+{
+	if (f2fs_encrypted_inode(inode))
+		return f2fs_get_encryption_info(inode) ? -EACCES : 0;
+	return 0;
+}
+
 const struct file_operations f2fs_dir_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
 	.iterate	= f2fs_readdir,
 	.fsync		= f2fs_sync_file,
+	.open		= f2fs_dir_open,
 	.unlocked_ioctl	= f2fs_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl   = f2fs_compat_ioctl,