File system having deferred verification of data integrity

• US 20070005614A1
• Filed: 07/01/2005
• Published: 01/04/2007
• Est. Priority Date: 07/01/2005
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Company (Blackberry Limited)
• Inventors: Dodge, Dan
• Granted Patent: US 7,809,777 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata

Abstract

A computer system that is used in implementing a transaction based file system is disclosed. The computer system includes a processor, random access memory that is accessible by the processor, and a persistent data storage device that is likewise accessible by the processor. The computer system also includes file system software. The file system software is executed by the processor and operates to manage the file data and the file system structure of the files stored on the persistent data storage device. Additionally, the file system software maintains a transaction file that includes a plurality of transaction records. Each of the transaction records has a header section and a data section. The header section of each transaction record includes one or more fields that are designated to store information corresponding to a file transaction that is represented by the transaction record. If the operation of the file system software is interrupted, the file system software resumes its execution using a startup process in which a reconstructed file system is generated in the random access memory. During system restart, the startup process skips verification of the data section of a transaction record when the transaction record meets one or more predetermined criterion. Instead, verification of the data section is deferred until some time after the file system startup process has completed. For example, the file system software may verify previously unverified data sections of each transaction record representing a given file upon a first or subsequent access of the given file, provided that the file access occurs after completion of the file system startup process.

Claims

1. A computer system comprising:

a processor;

random access memory accessible by the processor;

a persistent data storage device accessible by the processor;

file system software executable by the processor for managing file data and file system structure of files stored on the persistent data storage device;

a transaction file maintained by the file system software, where the transaction file includes a plurality of transaction records, and each transaction record comprises a header section and a data section, where the header section of each transaction record includes one or more fields containing information corresponding to a file transaction that is represented by the transaction record;

where the file system software executes a startup process in which a reconstructed file system is generated in the random access memory, and the startup process skips verification of information stored in the data section of a transaction record when the transaction record meets on one or more predetermined criterion; and

where the file system software verifies previously unverified data sections of each transaction record representing a given file upon a first or subsequent access of the given file occurring after completion of the startup process.

4. A computer system as claimed in claim 1 where the startup process verifies information stored in the header section of multiple transaction records.

5. A computer system as claimed in claim 1 where the startup process verifies an error correction code field to check information stored in the header section of multiple transaction records.

6. A computer system as claimed in claim 1 where the persistent data storage device comprises flash-like media.

7. A computer system as claimed in claim 6 where the flash-like media is organized into memory blocks, and where each memory block comprises multiple memory pages.

8. A computer system as claimed in claim 1 where the reconstructed file system comprises a regenerated file hierarchy and an extents table.

9. A computer system as claimed in claim 8 where the regenerated file hierarchy is organized by the file system software as an inverted file hierarchy.

10. A computer system as claimed in claim 1 where the startup process skips verification of information stored in the data section of a transaction record unless the transaction record affects metadata of the file system structure, and where the startup process verifies information stored in both the header section and the data section of a transaction record win the transaction record affects metadata of the file system structure.

11. A computer system as claimed in claim 7 where the startup process verifies information in the header section of a first occurring transaction record in a sequence of transaction records while skipping any verification of tailing transaction records when the first occurring transaction record and tailing transaction records are stored in the same memory block and affect the same file.

2. A computer system comprising:

a processor;

random access memory accessible by the processor;

a persistent data storage device accessible by the processor;

file system software executable by the processor for managing file data and file system structure of files stored on the persistent data storage device;

a transaction file maintained by the file system software, the transaction file including a plurality of transaction records, where each transaction record comprises a header section and a data section, and the header section of each transaction record includes one or more fields containing information corresponding to a file transaction that is represented by the transaction record;

where the file system software executes a startup process in which a reconstructed file system is generated in the random access memory, and the startup process skips verification of information stored in the data section of a transaction record unless the transaction record affects metadata of the file system structure,

where the startup process verifies information stored in both the header section and data section of a transaction record affecting metadata of the file system structure, and

where the file system software verifies previously unverified data sections of each transaction record representing a given file upon a first or subsequent access of the given file occurring after completion of the startup process.

12. A computer system as claimed in claim 2 where the startup process verifies information stored in the header section of multiple transaction records.

13. A computer system as claimed in claim 2 where the startup process verifies an error correction code field to check information stored in the header section of multiple transaction records.

14. A computer system as claimed in claim 2 where the persistent data storage device comprises flash-like media.

15. A computer system as claimed in claim 14 where the flash-like media is organized into memory blocks, and where each memory block comprises multiple memory pages.

16. A computer system as claimed in claim 2 where the reconstructed file system comprises a regenerated file hierarchy and an extents table.

17. A computer system as claimed in claim 16 where the regenerated file hierarchy is organized by the file system software as an inverted file hierarchy.

18. A computer system as claimed in claim 14 where the startup process verifies information in the header section of a first occurring transaction record in a sequence of transaction records while skipping any verification of tailing transaction records when the first occurring transaction record and tailing transaction records are stored in the same memory block and affect the same file.

3. A computer system comprising:

a processor;

random access memory accessible by the processor;

a persistent data storage device accessible by the processor;

file system software executable by the processor for managing file data and file system structure of files stored on the persistent data storage device;

a transaction file maintained by the file system software in flash media, the flash media being organized into memory blocks, where each memory block includes a plurality of memory pages, and the transaction file includes a plurality of transaction records, where each transaction record comprises a header section and a data section, and the header section of each transaction record includes one or more fields containing information corresponding to a file transaction that is represented by the transaction record;

where the file system software executes a startup process in which a reconstructed file system is generated in the random access memory, and the startup process verifies information in the header section of a first occurring transaction record in a sequence of transaction records while skipping any verification of tailing transaction records when the first occurring transaction record and tailing transaction records are stored in the same memory block and affect the same file, and

where the file system software verifies previously unverified header and/or data sections of each transaction record representing a given file upon a first or subsequent access of the given file occurring after completion of the startup process.

19. A computer system as claimed in claim 3 where the startup process verifies information stored in the header section of multiple transaction records.

20. A computer system as claimed in claim 3 where the startup process verifies an error correction code field to check information stored in the header section of multiple transaction records.

21. A computer system as claimed in claim 3 where the reconstructed file system comprises a regenerated file hierarchy and an extents table.

22. A computer system as claimed in claim 21 where the regenerated file hierarchy is organized by the file system software as an inverted file hierarchy.

23. A computer system as claimed in claim 3 where the startup process skips verification of information stored in the data section of a transaction record unless the transaction record affects metadata of the file system structure, and where the startup process verifies information stored in both the header section and the data section of a transaction record win the transaction record affects metadata of the file system structure.

24. A computer system as claimed in claim 23 where the startup process verifies information in the header section of a first occurring transaction record in a sequence of transaction records while skipping any verification of tailing transaction records when the first occurring transaction record and tailing transaction records are stored in the same memory block and affect the same file.