Cake2.x Prevent access to logged-in users

Plugins
1

When cake2.x performs the login process and the logged-in user tries to access the login action again, I want to get the user information of the logged-in user and redirect to another page if logged in, but it does not work.

To check whether you are logged in or not, there is a way to judge whether the information is in $this->Auth->user() by using $this->auth->loggedIn, so $this->Auth->user I wrote a process that uses () to get the login information and redirect it, but the logged-in user will be accessed. I would like to ask someone who can understand the cause.

Addendum
If you enter the controller and a cushion from the url that can be redirected when you go from the link to login, it will be accessed

class AppController extends Controller {
    public $helpers = array('Html', 'Form', 'Flash', 'Session');
    public $components = array(
        'DebugKit.Toolbar',
        'Flash',
        'Session',
        'Auth' => array(
            'loginRedirect' => array(
                'controller' => 'posts',
                'action' => 'index'
            ),
            'logoutRedirect' => array(
                'controller' => 'posts',
                'action' => 'index'
            ),
            'authenticate' => array(
                'Form' => array(
                    'passwordHasher' => 'Blowfish',
                    'fields' => array(
                        'username' => 'email',
                        'password' => 'password'
                    )
                )
            ),
            'loginAction' => array(
                'controller' => 'users',
                'action' => 'login'
            ),
            'unauthorizedRedirect' => array(
                'controller' => 'posts',
                'action' => 'index'
            ),
            'authorize' => array('Controller')
        )
    );
    public function beforeFilter() {
        $this->Auth->allow('index', 'view');
        $this->set('auth', $this->Auth->user());
   }

}

   public function login() {
   $login_id = $this->Auth->user('id');
   if ($login_id) {
      $this->Flash->error(__('You are logged in'));
      return $this->redirect(array('controller' => 'posts', 'action' => 'index'));
   }
   if ($this->request->is('post')) {
     if ($this->Auth->login()) {
       $this->Flash->success(__('Login succeeded));
       $this->redirect($this->Auth->redirectUrl());
   } else {
     $this->Flash->error(__('wrong email address or password'));
   }
 }