I need to recursively rename every file and directory. I convert spaces to underscores and make all file/directory names to lowercase. How can I make the following script rename all files in one run? Currently the script needs to be run several times before all the files/directories are converted. The code is below:

#!/usr/bin/perl

use File::Find;

$input_file_dir = $ARGV[0];

sub process_file {
        $clean_name=lc($_);
        $clean_name=~s/\s/_/g;
        rename($_,$clean_name);
        print "file/dir name: $clean_name\n";
}
find(\&process_file, $input_file_dir);