title: before_filter with another controller
body: <p>I am trying to create an action that will check for every page if the user is logged in.
  For that, in the controller <code>Home</code> I created this method:</p>
  
  <pre><code>def check_session
    if !session[:user_id]
      redirect_to :action=&gt; 'login'
    end
  end
  </code></pre>
  
  <p>And I've put this code at the head of the controller:</p>
  
  <pre><code>before_filter :check_session, :except =&gt; [:sub_layout, :authenticate, :login]
  </code></pre>
  
  <p>Now I want to use <code>check_session</code> from outside the pages of <code>Home</code>, lets say in the pages of <code>Users</code>. What is the correct syntax for calling a method of a different controller in the <code>before_filter</code>?</p>