Wordpress - redirect all attachment pages to parent post or home page

functions.php

// redirect attachment pages to home
function ljxdm_redirect_attachment_pages() {
  if(is_attachment()) {
    global $post;
    if($post && $post->post_parent) {
      wp_redirect(esc_url(get_permalink($post->post_parent)), 301);
      exit;
    } else {
      wp_redirect(esc_url(home_url('/')), 301);
     	exit;
    }
  }
}
add_action( 'template_redirect', 'ljxdm_redirect_attachment_pages' );