Error detection for files

• US 8,984,233 B2
• Filed: 06/20/2014
• Issued: 03/17/2015
• Est. Priority Date: 06/17/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Miller, Thomas J., Cargille, Jonathan M., Tipton, William R., Verma, Surendra
• Primary Examiner(s): ELMORE, STEPHEN C
• Application Number:
  US14/310,892
• Publication Number:
  US 20140304550A1
• Time in Patent Office: 270 Days
• Field of Search: 711/141, 711/154, 711/156, 714/52, 714/54, 714/746, 714/764
• US Class Current: 711/141
• 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

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 for maintaining a flag associated with a file, the actions comprising:

first marking the file as clean, where the first marking comprises setting a flag to indicate that the file is clean and then writing the flag set to indicate that the file is clean to storage;

receiving a request to change the file, where the received request is a first request to change the file since the first marking;

second marking, in response to the received request, the file as dirty, where the second marking comprises setting a flag to indicate that the file is dirty and then writing flag set to indicate that the file is dirty to the storage;

changing, after the second marking is successfully completed, the file according to the received request;

writing, after the changing, at least a portion of the changed file to storage; and

third marking, after the writing is successfully completed, the file as clean, where the third marking comprises setting the flag to indicate that the file is dean and then writing the flag set to indicate that the file is clean to the storage.

2. The system of claim 1, where the first marking the file as clean, when successfully completed, indicates that all data of the file and any associated error codes have been successfully written to the storage.

3. The system of claim 1, where the second marking the file as dirty, when successfully completed, indicates that the file is potentially dirty.

4. The system of claim 1, where the third marking the file as clean, when successfully completed, indicates that all data of the changed file and any associated error codes have been successfully written to the storage.

5. The system of claim 1, where the storage is non-volatile storage as oppose to cache.

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

7. The system of claim 1, where the writing is part of a flush operation.

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

first marking the file as clean, where the first marking comprises setting a flag to indicate that the file is clean and then writing the flag set to indicate that the file is clean to storage;

receiving a request to change the file, where the received request is a first request to change the file since the first marking;

second marking, in response to the received request, the file as dirty, where the second marking comprises setting a flag to indicate that the file is dirty and then writing flag set to indicate that the file is dirty to the storage;

changing, after the second marking is successfully completed, the file according to the received request;

writing, after the changing, at least a portion of the changed file to storage; and

third marking, after the writing is successfully completed, the file as clean, where the third marking comprises setting the flag to indicate that the file is clean and then writing the flag set to indicate that the file is clean to the storage.

9. The method of claim 8, where the first marking the file as clean, when successfully completed, indicates that all data of the file and any associated error codes have been successfully written to the storage.

10. The method of claim 8, where the second marking the file as dirty, when successfully completed, indicates that the file is potentially dirty.

11. The method of claim 8, where the third marking the file as dean, when successfully completed, indicates that all data of the changed We and any associated error codes have been successfully written to the storage.

12. The method of claim 8, where the storage is non-volatile storage as oppose to cache.

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

14. The method of claim 8, where the writing is part of a flush operation.

15. At least one memory storage device storing computer-executable instructions that, when executed by a computing device, cause the computing device to perform actions comprising:

first marking the file as dean, where the first marking comprises setting a flag to indicate that the file is clean and then writing the flag set to indicate that the file is clean to storage;

receiving a request to change the file, where the received request is a first request to change the file since the first marking;

second marking, in response to the received request, the file as dirty, where the second marking comprises setting a flag to indicate that the file is dirty and then writing flag set to indicate that the file is dirty to the storage;

changing, after the second marking is successfully completed, the file according to the received request;

writing, after the changing, at least a portion of the changed file to storage; and

third marking, after the writing is successfully completed, the file as clean, where the third marking comprises setting the flag to indicate that the file is clean and then writing the flag set to indicate that the file is clean to the storage.

16. The at least one memory storage device of claim 15, where the first marking the file as clean, when successfully completed, indicates that all data of the file and any associated error codes have been successfully written to the storage.

17. The at least one memory storage device of claim 15, where the second marking the file as dirty, when successfully completed, indicates that the file is potentially dirty.

18. The at least one memory storage device of claim 15, where the third marking the file as clean, when successfully completed, indicates that all data of the changed file and any associated error codes have been successfully written to the storage.

19. The at least one memory storage device of claim 15, where the storage is non-volatile storage as oppose to cache.

20. The at least one memory storage device of claim 15, where the writing includes a race condition resulting from writing of file data and any associated error codes.