linux ubuntu nginx上傳文件413錯誤

php：修改配置文件/etc/php5/fpm/php.ini

upload_max_filesize = 20M  
post_max_size = 20M

nginx:修改配置文件 /etc/nginx/sites-enabled/xxxx

server {  
    ...  
    client_max_body_size 20m;  
    ...  
}