Php codeigniter如何将图片上传到文件夹、web/assets/picture/

我正在使用codeigniter，我想将文件图片上传到我的文件夹， 路径是web/assets/picture/

我看了这里，找不到答案。请帮忙

这是我的视图，用于输入图片：

echo form_open_multipart("adminFolder/admin/insert_picture");   
echo form_upload("userfile", "Gambar Picture"); 
echo form_submit("input_picture", "Input now !!!");

我的控制器插入图片：

echo form_open_multipart("adminFolder/admin/insert_picture");   
echo form_upload("userfile", "Gambar Picture"); 
echo form_submit("input_picture", "Input now !!!");

        if($this->input->post("userfile")){
            $this->model_get->doUpload();

            $this->adminPic();
        }else{
            $this->insertPicture();
        }

我的模型：

function doUpload(){

        $config['upload_path'] = '../assets/images/'; 
        $config['allowed_types'] = 'gif|jpg|png|jpeg'; 
        $config['max_size'] = '2048'; 
        $config['max_width']  = '1024';
        $config['max_height']  = '768'; 
        $config['overwrite'] = TRUE;

        $this->load->library("upload", $config);
        $this->upload->do_upload(); 
    }

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将上载路径设置为：

$config['upload_path'] = FCPATH . 'web/assets/picture/';

FCPATH常量返回主目录的路径

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确保目录存在且可写。

如何检查目录的权限？？我该如何改变它？？