f2fs: don't allow to get pino when filename is encrypted

After renaming an encrypted file, we have no way to get its
encrypted filename from its dentry.
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -110,6 +110,9 @@ static int get_parent_ino(struct inode *inode, nid_t *pino)
 {
 	struct dentry *dentry;
 
+	if (file_enc_name(inode))
+		return 0;
+
 	inode = igrab(inode);
 	dentry = d_find_any_alias(inode);
 	iput(inode);