How should I use DB Transactions

I have now done it this way but if there is a error on my file upload section how to roll it back also.

PHP Code:

<?php

class Add_user_model extends CI_Model {

 public function insert_user($file_name = array()) {
 $this->db->trans_begin();

 $user = array(
 'status' => $this->input->post('status'),
 'date_added' => date('Y-m-d')
 );

 $this->db->set($user);
 $this->db->insert($this->db->dbprefix . 'user');

 $user_id = $this->db->insert_id();

 $options = [
    'cost' => 12,
 ];

 $hash = password_hash($this->input->post('password'), PASSWORD_BCRYPT, $options);

 $userdata = array(
 'user_id' => $user_id,
 'username' => $this->input->post('username'),
 'password' => $hash,
 'firstname' => $this->input->post('firstname'),
 'lastname' => $this->input->post('lastname'),
 'email' => $this->input->post('email'),
 'image' => ($file_name) ? $file_name : '',
 'country_code' => $this->input->post('country'),
 'timezone' => $this->input->post('timezone')
 );

 $this->db->set($userdata);
 $this->db->insert($this->db->dbprefix . 'user_data');

 if ($this->db->trans_status() === FALSE) {
    
    $this->db->trans_rollback();

 } else {

    $this->db->trans_commit();
 } 
 }
} 


Controller

PHP Code:

<?php

class Add extends MY_Controller {

 private $error = array();

 public function __construct() {
 parent::__construct();
 $this->load->library('form_validation');
 $this->load->library('countries');
 $this->load->library('upload');
 $this->load->model('admin/user/add_user_model');
 }

 public function index() {
 $data['timezones'] = DateTimeZone::listIdentifiers(DateTimeZone::ALL);

 $this->form_validation->set_rules('username', 'Username', 'trim|required');
 $this->form_validation->set_rules('firstname', 'Firstname', 'trim|required');
 $this->form_validation->set_rules('lastname', 'Lastname', 'trim');
 $this->form_validation->set_rules('email', 'Email', 'trim|valid_email');
 $this->form_validation->set_rules('password', 'Password', 'trim');
 $this->form_validation->set_rules('confirm_password', 'Confirm Password', 'trim|matches[password]');
 $this->form_validation->set_rules('status', 'Status', 'trim|required|callback_status[status]');
 $this->form_validation->set_rules('country', 'Country', 'trim|required|callback_country[country]');
 $this->form_validation->set_rules('timezone', 'Time Zone', 'trim|required|callback_timezone[timezone]');

 $this->form_validation->set_message('required', '<b>{field}</b> must be set!');

 if ($this->form_validation->run($this)) {

 if (isset($_FILES['userfile']) && $_FILES['userfile']['size'] > 0) {

 if (!is_dir(FCPATH . 'uploads/users/' . $this->input->post('username') . '/')) {
 mkdir(FCPATH . 'uploads/users/' . $this->input->post('username') . '/');
 }
 
 $config['upload_path'] = './uploads/users/' . $this->input->post('username') . '/';
                $config['allowed_types'] = 'gif|jpg|png';
                $config['max_size'] = 3000;
                $config['max_width'] = 0;
                $config['max_height'] = 0;

                $this->upload->initialize($config);

                if (!$this->upload->do_upload('userfile')) {
                 $this->error['warning'] = $this->upload->display_errors();
                }

                $upload_data = $this->upload->data();
 }

 $this->add_user_model->insert_user($upload_data['file_name']);
 }

 if (validation_errors() != false) {
 $this->error['warning'] = validation_errors('<div class="alert alert-danger">', '</div>');
 }

 if (isset($this->error['warning'])) {
 $data['warning_error'] = $this->error['warning'];
 } else {
 $data['warning_error'] = '';
 }

 $data['countries'] = $this->countries->get();

 $data['header'] = Modules::run('admin/common/header/index');
 $data['footer'] = Modules::run('admin/common/footer/index');

 $this->load->view('user/add_view', $data);
 }

 public function country($str) {
 if ($str) {
 return true;
 } else {
 $this->form_validation->set_message('country', '<b>{field}</b> must be set!');
 return false;
 }
 }

 public function timezone($str) {
 if ($str) {
 return true;
 } else {
 $this->form_validation->set_message('timezone', '<b>{field}</b> must be set!');
 return false;
 }
 }

 public function status($str) {
 if ($str) {
 return true;
 } else {
 $this->form_validation->set_message('status', '<b>{field}</b> must be set!');
 return false;
 }
 }
} 


If you include the file upload section inside the try catch block then any errors should go the catch portion where you roll back the transaction. I say should but you will want to test by making deliberate errors in the file uploads and in the database inserts.