1. A method performed by a computer, the method comprising: receiving a request to update a file; refraining from updating the file until after a dirty flag for the file has been written to non-volatile storage; setting a dirty flag to indicate the file is potentially dirty; sending a request to write the dirty flag to the non-volatile storage; receiving an indication that the dirty flag has been written to the non-volatile storage; and after receiving the indication, updating, by the computer, the file in accordance with the request to update the file.