1. A method in a data processing system for managing data in a file system, the method comprising: detecting a request to modify a data block in the file system; responsive to detecting the request, writing metadata describing the data block in the file system into a snapshot image; copying data for the data block in the file system to the snapshot image; and modifying the data block in the file system after copying of the data in the data block to the snapshot image has occurred, wherein the snapshot image may be used to return the file system to a state prior to modifying the data block in the file system.