location /upload/ {
  rewrite ^ http://site.com$request_uri permanent;
}

如果你在同一个服务器块中捕获site.com和* .site.com,则需要添加一个额外的if语句：

location /upload/ {
  if( $host != site.com ) {
    rewrite ^ http://site.com$request_uri permanent;
  }
  # if we get here it's the main site
  # directives for serving http://site.com/upload/ go here
}