Wordpress redirect attachment page to parent

redirect-attachment.php

<?php

// Redirect an attachment page to its parent. Opening the actual attachments is still valid
add_action( 'template_redirect', 'void_attachment_parent', 1 );

if (!function_exists('void_attachment_parent')) :
    function void_attachment_parent() {
        global $post;
        if ( is_attachment()): 
            // Optionally check file type and perform redirect for some files only.
            // $filetype = wp_check_filetype( wp_get_attachment_url());

            if ( isset( $post->post_parent ) &&
                is_numeric( $post->post_parent ) &&
                ( $post->post_parent !== 0 ) &&
                get_post_status( $post->post_parent ) !== 'trash'
                ) :
                wp_safe_redirect( get_permalink( $post->post_parent ), 301 );
                exit();
                wp_reset_postdata();
            endif;
        endif;
    }
endif;
?>