WordPress: Show all posts containing media/attachment

load-related-attachments.php

<?php 
/**
 * Supporting script to load posts containing attachement. 
 * Using AJAX because query slows down page load.
*/
function duffy_register_ajax_load_related() {
	$current_screen = get_current_screen();
	
	if ( !is_null($current_screen) && $current_screen->base == 'post' && $current_screen->post_type == 'attachment' ) {
		// javascript directory variables
		$js = plugin_dir_url(__FILE__) . 'js/';
		
		// register scripts
		wp_register_script( 'ajax-load-related', $js . 'load-related.js', array( 'jquery' ) );
		wp_localize_script( 'ajax-load-related', 'myAjax', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );
		wp_enqueue_script( 'jquery' );
		wp_enqueue_script( 'ajax-load-related' );
	}
}
add_action( 'admin_enqueue_scripts', 'duffy_register_ajax_load_related' );

/**
 * Create metabox to list posts containing attachement, initially empty
*/
function duffy_list_attachment_posts_meta() {
	add_meta_box( 'list-attachment-posts-meta', 
		'Related Posts', 
		'duffy_list_attachment_posts_callback',
		'attachment',
		'side',
		'low'
	);
}
add_action( 'admin_init', 'duffy_list_attachment_posts_meta' );

/* Meta box initially contains post ID to pass to ajax function */
function duffy_list_attachment_posts_callback() {
	global $post;
	echo '<span id="' . $post->ID .'"></span>';
}

/**
 * AJAX function to list all posts referencing/containing the attachment
*/	
function duffy_load_related() {
	global $post, $all_post_types;
	$postID = (isset($_GET['postid'])) ? $_GET['postid'] : 0;
	
	// get attachment metadata
	$metadata = wp_get_attachment_metadata($postID);
	$filename = $metadata[file];
	
	// remove the last 4 characters from file (extension and . - '.jpg' or '.gif')
	$filename = substr($filename, 0, -4);

	// query for all posts containing that file (or resized variations)
	$search_args = array(
		'post_type'   => $all_post_types,
		'numberposts' => 500,
		's'           => $filename
	);
	    
	if ($filename != '') {
		$posts_containing_image = get_posts($search_args);
	}

	// Posts that contain the image in the body content ?>
	<h4 style="margin-bottom: 0;">Posts Containing Image:</h4>
	<?php if ($posts_containing_image) { ?>
		<ul style="margin-top: 0;">
		<?php foreach ( $posts_containing_image as $post ) : setup_postdata( $post ); ?>
			<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
		<?php endforeach; ?>
		</ul>
	<?php } else { ?>
		<p style="margin-top: 0;">None found.</p>	    	
	<?php }
	
	// Posts that use this image as featured image	
	$values_serialized = array($postID);
	$featured_args = array(
		'post_type'   => $all_post_types,
		'meta_query'  => array (
			array(
		  	'key'     => '_thumbnail_id',
		  	'value'   => $values_serialized,
		  	'compare' => 'IN'
			)
		),
		'numberposts' => 500
	);
	$posts_featured_image = get_posts($featured_args); ?>
	
	<h4 style="margin-bottom: 0;">Posts Featuring Image:</h4>				
	<?php if ($posts_featured_image) { ?>
		<ul style="margin-top: 0;">
		<?php foreach ( $posts_featured_image as $post ) : setup_postdata( $post ); ?>
			<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
		<?php endforeach; ?>
	</ul>
	<?php
		} else { ?>
			<p style="margin-top: 0;">None found.</p>	    	
	<?php }
	    
	die();
}
add_action("wp_ajax_duffy_load_related", "duffy_load_related");
add_action("wp_ajax_nopriv_duffy_load_related", "duffy_load_related");

load-related.js

/* List posts containing the attachment */

jQuery(function($){
	var loading = true;
	var postid = $('#list-attachment-posts-meta .inside span').attr('id');
	var $content = $("#list-attachment-posts-meta .inside");
	var load_related_posts = function(){
		$.ajax({
			type       : "GET",
			data       : {action: "duffy_load_related", "postid": postid},
			dataType   : "html",
			url        : myAjax.ajaxurl,
			beforeSend : function(){
				$content.append('<img id="temp_load" src="ajax-loader.gif" style="display: block; margin: 10px auto;" />');
			},
			success    : function(data) {
			        $data = $(data);
			        if ( $data.length ){
			          $data.hide();
			          $content.append($data);
			          $("#temp_load").remove();
			          loading = false;
			          $data.fadeIn(500);
			        } else {
			          $("#temp_load").remove();
			        }
			},
			error     : function(jqXHR, textStatus, errorThrown) {
				$("#temp_load").remove();
				alert(jqXHR + " :: " + textStatus + " :: " + errorThrown);
			}
		});
	}
	load_related_posts();
});