Alenija

namespace MyUserBundle\Controller;

use FOS\UserBundle\Controller\SecurityController as ParentSecurityController;
use Symfony\Component\HttpFoundation\RedirectResponse;
use Symfony\Component\HttpFoundation\Request;

class SecurityController extends ParentSecurityController
{

    public function loginAction(Request $request)
    {
        if (!$this->container->get('security.context')->isGranted('IS_AUTHENTICATED_ANONYMOUSLY'))
        {
            return new RedirectResponse('/');
        }

        return parent::loginAction($request);
    }