Preserving file metadata during atomic save operations

• US 8,620,861 B1
• Filed: 09/30/2008
• Issued: 12/31/2013
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Uhrhane, Eric Joseph, Bradshaw, Peter, Cairns, Ryan Tyler
• Primary Examiner(s): Saeed, Usmaan
• Assistant Examiner(s): Zhao, Yu
• Application Number:
  US12/242,818
• Time in Patent Office: 1,918 Days
• Field of Search: None
• US Class Current: 707/610
• CPC Class Codes: G06F 16/1873 Versioning file systems, temporal file systems, e.g. file system supporting different historic versions of files

Abstract

A method of preserving file metadata associated with an edited file, performed on a client device, includes storing in a log information denoting a plurality of create, delete, and rename operations on one or more files in a file system, and determining when two or more operations denoted in the log, including an operation involving a first file and another operation involving a second file, comprise an atomic save of a respective file, the first file comprising a first version of the respective file, and the second file comprising a second version of the respective file, the first file and second file each having associated metadata. The method further includes associating a subset of the metadata of the first file with the second file, such that at least one of a globally unique file identifier and file access permissions associated with the first file become associated with the second file.

Claims

1. A method of preserving directory metadata associated with an edited directory, comprising:

on a client device;

storing in a log information denoting a plurality of create, delete, and rename operations for one or more directories in a file system and one or more files in the one or more directories;

identifying in the log two or more file system operations denoted in the log, including an operation involving a first directory and another operation involving a second directory, that together comprise an atomic operation, which is an atomic save of a respective directory, the first directory comprising a first version of the respective directory, and the second directory comprising a second version of the respective directory that is subsequent to the first version of the respective directory, the first directory and second directory each having associated metadata;

in accordance with the identification of the two or more file system operations as comprising the atomic operation, the atomic operation comprising said atomic save of the respective directory, revising metadata of the second directory with a subset of the metadata of the first directory;

identifying, in the respective atomically saved directory, a set of files associated with the respective directory;

for a respective file in the identified set of files, the respective file having a corresponding first file in the first version of the respective directory and second file in the second version of the respective directory, the first file and second file each having associated metadata, associating a subset of the metadata of the first file with the second file, such that at least one of a globally unique file identifier and file access permissions associated with the first file become associated with the second file; and

performing a synchronization with a server system, the synchronization utilizing the second file in conjunction with the globally unique file identifier to synchronize at least one of content and metadata of the second file on the client device with corresponding information stored at the server system with respect to the globally unique file identifier.

2. The method of claim 1, wherein associating a subset of the metadata of the first file with the second file comprises swapping a subset of the metadata of the second file with the subset of the metadata of the first file.

3. The method of claim 1, wherein the metadata of the first file and the metadata of the second file are stored on the client device in a metadata data structure separate from content of the first file and second file.

4. The method of claim 3, wherein the metadata of the first file includes a pointer to the content of the first file and the metadata of the second file includes a pointer to the content of the second file.

5. The method of claim 1, wherein the metadata of the first file includes a first metadata set created prior to the operation involving the first directory and a second metadata set that includes values of metadata created by the operation involving the first directory, wherein the metadata of the second file includes a third metadata set created prior to the operation involving the second directory and a fourth metadata set that includes values created by the operation involving the second directory, and the identifying two or more file system operations includes matching a filename in the first metadata set and the fourth metadata set.

6. The method of claim 5, wherein associating a subset of the metadata of the first file with the second file includes swapping a subset of the third metadata set with a subset of the first metadata set.

7. The method of claim 5, wherein associating a subset of the metadata of the first file with the second file includes swapping a subset of the fourth metadata set with a subset of the second metadata set.

8. The method of claim 5, wherein the identifying two or more file system operations further includes determining that the third metadata set comprises entirely null values.

9. The method of claim 1, wherein the two or more file system operations are identified to comprise an atomic save operation when one or more predefined criteria are satisfied, and one of the predefined criteria is that the two or more operations were performed by the same instance of an application.

10. The method of claim 9, wherein another of the predefined criteria is that the first file has been synchronized with a remote server.

11. The method of claim 9, wherein another of the predefined criteria is that the metadata of the second file does not include a delete instruction.

12. The method of claim 9, wherein another of the predefined criteria is that the metadata of the first file includes a delete instruction.

13. The method of claim 1, further comprising:

synchronizing with a remote server metadata database at least portions of the metadata of at least one of the first file and the second file.

14. The method of claim 1, further comprising:

determining if the log contains information for a file scheduled for synchronization with a remote server;

so long as the log contains information for the file scheduled for synchronization, inhibiting the synchronization; and

if the log does not contain information for the file scheduled for synchronization, synchronizing metadata for the file with the remote server.

15. The method of claim 1, comprising:

obtaining content from the first file and content from the second file;

comparing the content from the second file with the content from the first file to obtain a content difference;

synchronizing the content difference with a remote server content database.

16. The method of claim 1, wherein associating a subset of the metadata of the first file with the second file includes updating a subset of the metadata of the second file with a subset of the metadata of the first file such that the second file metadata includes two or more of the set consisting of:

a globally unique file identifier, a version number, access permissions, a creation time, and server metadata of the first file.

17. The method of claim 16, wherein a subset of the metadata of the second file also includes one or more of the set consisting of:

a content pointer, a modification time, a file name, a file directory, and a delete instruction of the second file metadata.

18. The method of claim 1, comprising:

in response to a user request, displaying metadata and/or content history information associated with a respective file, wherein the content history information includes at least one atomic save.

19. The method of claim 1, further comprising:

removing information regarding a particular operation in the log after the information has resided in the log for at least a predetermined period of time; and

conditionally removing information regarding the particular operation in the log if information regarding at least a predetermined number of additional operations have subsequently been stored in the log.

20. A system for preserving directory metadata associated with an edited directory, comprising:

one or more processors;

memory; and

one or more programs stored in the memory, the one or more programs comprising instructions to;

store in a log information denoting a plurality of create, delete, and rename operations for one or more directories in a file system and one or more files in the one or more directories;

identify in the log two or more file system operations denoted in the log, including an operation involving a first directory and another operation involving a second directory, that together comprise an atomic operation, which is an atomic save of a respective directory, the first directory comprising a first version of the respective directory, and the second directory comprising a second version of the respective directory that is subsequent to the first version of the respective directory, the first directory and second directory each having associated metadata;

in accordance with the identification of the two or more file system operations as comprising the atomic operation, the atomic operation comprising said atomic save of the respective directory, revise metadata of the second directory by associating a subset of the metadata of the first directory;

identify, in the respective atomically saved directory, a set of files associated with the respective directory;

for a respective file in the identified set of files, the respective file having a corresponding first file in the first version of the respective directory and second file in the second version of the respective directory, the first file and second file each having associated metadata, associate a subset of the metadata of the first file with the second file, such that at least one of a globally unique file identifier and file access permissions associated with the first file become associated with the second file; and

perform a synchronization with a server system, the synchronization utilizing the second file in conjunction with the globally unique file identifier to synchronize at least one of content and metadata of the second file on the client device with corresponding information stored at the server system with respect to the globally unique file identifier.

21. The system of claim 20, wherein associating a subset of the metadata of the first file with the second file comprises swapping a subset of the metadata of the second file with the subset of the metadata of the first file.

22. The system of claim 20, wherein the metadata of the first file includes a first metadata set created prior to the operation involving the first directory and a second metadata set that includes values of metadata created by the operation involving the first directory, wherein the metadata of the second file includes a third metadata set created prior to the operation involving the second directory and a fourth metadata set that includes values created by the operation involving the second directory, and the identifying two or more file system operations includes matching a filename in the first metadata set and the fourth metadata set.

23. The system of claim 20, wherein the two or more file system operations are identified to comprise an atomic save operation when one or more predefined criteria are satisfied, and one of the predefined criteria is that the two or more operations were performed by the same instance of an application.

24. The system of claim 20, wherein the one or more programs further comprise instructions to synchronize with a remote server metadata database at least portions of the metadata of at least one of the first file and the second file.

25. The system of claim 20, wherein associating a subset of the metadata of the first file with the second file includes updating a subset of the metadata of the second file with a subset of the metadata of the first file such that the second file metadata includes two or more of the set consisting of:

a globally unique file identifier, a version number, access permissions, a creation time, and server metadata of the first file.

26. A non-transitory computer readable storage medium storing one or more programs configured for execution by one or more processors of a computer system for preserving directory metadata associated with an edited directory, the one or more programs comprising instructions to:

store in a log information denoting a plurality of create, delete, and rename operations for one or more directories in a file system and one or more files in the one or more directories;

identify in the log two or more file system operations denoted in the log, including an operation involving a first directory and another operation involving a second directory, that together comprise an atomic operation, which is an atomic save of a respective directory, the first directory comprising a first version of the respective directory, and the second directory comprising a second version of the respective directory that is subsequent to the first version of the respective directory, the first directory and second directory each having associated metadata;

in accordance with the identification of the two or more file system operations as comprising the atomic operation, the atomic operation comprising said atomic save of the respective directory, revise metadata of the second directory with a subset of the metadata of the first directory;

identify, in the respective atomically saved directory, a set of files associated with the respective directory;

for a respective file in the identified set of files, the respective file having a corresponding first file in the first version of the respective directory and second file in the second version of the respective directory, the first file and second file each having associated metadata, associate a subset of the metadata of the first file with the second file, such that at least one of a globally unique file identifier and file access permissions associated with the first file become associated with the second file; and

perform a synchronization with a server system, the synchronization utilizing the second file in conjunction with the globally unique file identifier to synchronize at least one of content and metadata of the second file on the client device with corresponding information stored at the server system with respect to the globally unique file identifier.

27. The non-transitory computer readable storage medium of claim 26, wherein associating a subset of the metadata of the first file with the second file comprises swapping a subset of the metadata of the second file with the subset of the metadata of the first file.

28. The non-transitory computer readable storage medium of claim 26, wherein the metadata of the first file includes a first metadata set created prior to the operation involving the first directory and a second metadata set that includes values of metadata created by the operation involving the first directory, wherein the metadata of the second file includes a third metadata set created prior to the operation involving the second directory and a fourth metadata set that includes values created by the operation involving the second directory, and the identifying two or more file system operations includes matching a filename in the first metadata set and the fourth metadata set.

29. The non-transitory computer readable storage medium of claim 26, wherein the two or more file system operations are identified to comprise an atomic save operation when one or more predefined criteria are satisfied, and one of the predefined criteria is that the two or more operations were performed by the same instance of an application.

30. The non-transitory computer readable storage medium of claim 26, wherein the one or more programs further comprise instructions to synchronize with a remote server metadata database at least portions of the metadata of at least one of the first file and the second file.

31. The non-transitory computer readable storage medium of claim 26, wherein associating a subset of the metadata of the first file with the second file includes updating a subset of the metadata of the second file with a subset of the metadata of the first file such that the second file metadata includes two or more of the set consisting of:

a globally unique file identifier, a version number, access permissions, a creation time, and server metadata of the first file.