ceph_encode_encrypted_dname
len = ceph_encode_encrypted_dname(dir, *p, len);
int ceph_encode_encrypted_dname(struct inode *parent, char *buf, int len);
err = ceph_encode_encrypted_dname(inode, req->r_path2, len);
len = ceph_encode_encrypted_dname(d_inode(parent),