How are file IDs and Object IDs used in the file systems? In my filter driver, how do I deal with them?
File IDs are a 64-bit identifier created by the file system to provide a volume-level unique identifier for a given file. The initial purpose behind creating such IDs was to allow certain types of applications (e.g., file servers) to associate a numeric identifier with the file. For example, the stateless NFS file system provides a handle to its clients. If the handle incorporates the file ID, it is possible for the file server to open the file at an arbitrary point in time by using the file ID, rather than by using a path to the file. In Windows 2000, Microsoft introduced the concept of an object ID. Object IDs are created by application programs and are optionally assigned to files by using the FSCTL_SET_OBJECT_ID, FSCTL_GET_OBJECT_ID, and FSCTL_DELETE_OBJECT_ID file system control operations. To retrieve the file ID for a file, an application program can query the “internal ID” of the file. The application then opens the file using this ID by using the ZwCreateFile API. The Object A
