WordPress: Link Attachments to the Post Displaying Them

attachment.php

<?php
if ( $attachment->post_parent > 0 ) {
	$link = get_permalink( $attachment->post_parent );
} else {
	$link = get_attachment_link( $attachment->ID );
}
$img  = wp_get_attachment_image( $attachment->ID );
?>
<a href="<?php echo $link ?>"><?php echo $img ?></a>

example.php

<?php
$args = array(
	'posts_per_page' => 5,
	'post_type'      => 'attachment'
);
$attachments = new WP_Query( $args );
if ( $attachments->have_posts() && $attachments->post_count >= 3 ) : ?>
	<div class="gallery">
		<div class="items">
			<?php foreach ( $attachments->posts as $attachment ):
				if ( $attachment->post_parent > 0 ) {
				     $link = get_permalink( $attachment->post_parent );
				} else {
				     $link = get_attachment_link( $attachment->ID );
				}
				$img  = wp_get_attachment_image( $attachment->ID, 'gallery' );
				?>
				<a href="<?php echo $link; ?>"><?php echo $img; ?></a>
			<?php endforeach; ?>
		</div>
	</div>
<?php endif; ?>
<?php wp_reset_query(); ?>