haven't heart any background check in Shang hai since 2005,

But 10-days is too short. I got H1-b in shang hai last year, it's no question ask, very quick. But they now change the process. You can't get your passport and visa in same day, they will mail your passport to you. It takes some days, if something wrong in mail system, it will be tatolly messed up. If your home is in Shang hai, maybe it's no problem. If your home is not in Shang Hai, you need find a mail address firstly. Also you need make a appointment at least one week before your back date.

good luck!