Error detection for files

• US 9,448,869 B2
• Filed: 07/24/2014
• Issued: 09/20/2016
• Est. Priority Date: 06/17/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Miller, Thomas J., Cargille, Jonathan M., Tipton, William R., Verma, Surendra
• Primary Examiner(s): ELMORE, STEPHEN C
• Application Number:
  US14/339,807
• Publication Number:
  US 20140337302A1
• Time in Patent Office: 789 Days
• Field of Search: 711/141, 711/154, 711/156, 714/52, 714/54, 714/746, 714/764
• US Class Current: 1/1
• CPC Class Codes: G06F 11/004 Error avoidance G06F11/07 and subgroups take precedence
• CPC Class Codes: G06F 11/0766 Error or fault reporting or storing
• CPC Class Codes: G06F 11/0772 Means for error signaling, e.g. using interrupts, exception flags, dedicated error registers
• CPC Class Codes: G06F 11/1004 to protect a block of data words, e.g. CRC or checksum G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00
• CPC Class Codes: G06F 11/1064 in cache or content addressable memories
• CPC Class Codes: G06F 11/1072 in multilevel memories
• CPC Class Codes: G06F 11/1402 Saving, restoring, recovering or retrying
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 12/0826 Limited pointers directories; State-only directories without pointers
• CPC Class Codes: G06F 12/0828 with concurrent directory accessing, i.e. handling multiple concurrent coherency transactions
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 16/178 Techniques for file synchronisation in file systems
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064

Abstract

Aspects of the subject matter described herein relate to error detection for files. In aspects, before allowing updates to a clean file, a flag marking the file as dirty is written to non-volatile storage. Thereafter, the file may be updated as long as desired. Periodically or at some other time, the file may be marked as clean after all outstanding updates to the file and error codes associated with the file are written to storage. While waiting for outstanding updates and error codes to be written to storage, if additional requests to update the file are received, the file may be marked as dirty again prior to allowing the additional requests to update the file. The request to write a clean flag regarding the file may be done lazily.

Claims

1. A system comprising a computing device and at least one program module that are together configured for performing actions comprising:

refraining from updating a file in response to an update request until after a dirty flag for the file has been written;

writing the dirty flag; and

updating, after the writing, the file in accordance with the update request.

2. The system of claim 1 where the received update request is direct to the file.

3. The system of claim 1, the actions further comprising setting, in response to the received update request, the dirty flag, where the set dirty flag indicates that the file is potentially dirty.

4. The system of claim 3, the actions further comprising receiving, in response to the setting, an indication that the set dirty flag has been successfully written.

5. The system of claim 4, where the updating is performed in response to the received indication.

6. The system of claim 4, where the writing is to non-volatile storage, not just to cache.

7. The system of claim 1, where the updating includes a race condition resulting from writing data and writing any error codes associated with the data.

8. A method performed on a computing device, the method comprising:

refraining, by the computing device, from updating a file in response to an update request until after a dirty flag for the file has been written;

writing, by the computing device, the dirty flag; and

updating, by the computing device after the writing, the file in accordance with the update request.

9. The method of claim 8 where the received update request is direct to the file.

10. The method of claim 8 further comprising setting, in response to the received update request, the dirty flag, where the set dirty flag indicates that the file is potentially dirty.

11. The method of claim 10 further comprising receiving, in response to the setting, an indication that the set dirty flag has been successfully written.

12. The method of claim 11, where the updating is performed in response to the received indication.

13. The method of claim 11, where the writing is to non-volatile storage, not just to cache.

14. The method of claim 8, where the updating includes a race condition resulting from writing data and writing any error codes associated with the data.

15. At least one memory storage device storing computer-executable instructions that, based on execution by a computing device, configure the computing device to perform actions comprising:

refraining from updating a file in response to an update request until after a dirty flag for the file has been written;

writing the dirty flag; and

updating, after the writing, the file in accordance with the update request.

16. The at least one memory storage device of claim 15, the actions further comprising setting, in response to the received update request, the dirty flag, where the set dirty flag indicates that the file is potentially dirty.

17. The at least one memory storage device of claim 16, the actions further comprising receiving, in response to the setting, an indication that the set dirty flag has been successfully written.

18. The at least one memory storage device of claim 17, where the updating is performed in response to the received indication.

19. The at least one memory storage device of claim 17, where the writing is to non-volatile storage, not just to cache.

20. The at least one memory storage device of claim 15, where the updating includes a race condition resulting from writing data and writing any error codes associated with the data, or where the received update request is direct to the file.