Get directory recursively in PHP

<?php/*  ww w .  j a  v a 2s.c  o m*/
    function directorySize($directory) {
   
        $directorySize=0;

        // Open the directory and read its contents.
        if ($dh = @opendir($directory)) {

            // Iterate through each directory entry.
            while (($filename = readdir ($dh))) {

                // Filter out some of the unwanted directory entries
                if ($filename != "." && $filename != "..")
                {

                    // File, so determine size and add to total
                    if (is_file($directory."/".$filename))
                        $directorySize += filesize($directory."/".$filename);

                    // New directory, so initiate recursion
                    if (is_dir($directory."/".$filename))
                        $directorySize += directorySize($directory."/".$filename);
                }
            }
        }

        @closedir($dh);
        return $directorySize;

    }

    $directory = '/usr/';
    $totalSize = round((directory_size($directory) / 1048576), 2);
    printf($totalSize);

?>