wp Mete box

function add_meta_boxes() {

     add_meta_box(
          'wpa-45985',
          'Extra Options',
          'wpa_meta_box_display',
          'dzsrst_items',
          'normal',
          'high');

} add_action('admin_menu', 'add_meta_boxes');


function wpa_meta_box_display() {
    global $post;
    wp_nonce_field( 'wpa_45985', 'wpa_45985_nonce' );


$meta = get_post_meta($post->ID, 'wpa_45985', true);

$font_awesome = isset($meta[font_awesome]) ? $meta[font_awesome] : '';
$custom_link = isset($meta[custom_link]) ? $meta[custom_link] : '';
?>
<!-- function.php -->
<label>Font Awesome</label>
<input type="text" class="widefat" name="wpa_45985[font_awesome]" placeholder="fa fa-font" value="<?php echo $font_awesome; ?>"/>
<br>
<label>Custom Link</label>
<input type="text" class="widefat" placeholder="http://" name="wpa_45985[custom_link]" value="<?php echo $custom_link; ?>"/>


<?php

}

add_action('save_post', 'wpa_meta_box_save');
function wpa_meta_box_save($post_id) {
    global $custom_meta_fields;
    if ( ! isset( $_POST['wpa_45985_nonce'] ) ||
        ! wp_verify_nonce( $_POST['wpa_45985_nonce'], 'wpa_45985' ) )
        return;

    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)
        return;

    if (!current_user_can('edit_post', $post_id))
        return;

    update_post_meta($post_id,'wpa_45985',$_POST['wpa_45985']);

}