Preserving file metadata during atomic save operations

• US 10,289,692 B2
• Filed: 11/25/2013
• Issued: 05/14/2019
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Uhrhane, Eric Joseph, Bradshaw, Peter, Cairns, Ryan Tyler
• Primary Examiner(s): Saeed, Usmaan
• Assistant Examiner(s): Zhao, Yu
• Application Number:
  US14/089,621
• Publication Number:
  US 20140081933A1
• Time in Patent Office: 1,996 Days
• Field of Search: None
• 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 file metadata associated with an atomic save operation, comprising:

on a device;

obtaining log information regarding a plurality of file system operations, wherein the plurality of file system operations include create, delete, and/or rename operations on one or more files in a file system;

identifying in the log two or more file system operations that together comprise an atomic save of a particular file of the one or more files;

wherein the two or more file system operations include a first operation involving a first version of the particular file and a second operation involving a second version of the particular file, the second version subsequent to the first version, and

wherein the first version has first metadata and the second version has second metadata, distinct from the first metadata; and

in accordance with the identification of the two or more file system operations as comprising said atomic save, replacing at least a portion of the second metadata with at least a portion of the first metadata, including replacing a globally unique file identifier and/or file access permissions;

wherein,

prior to the replacing, the second metadata includes a respective globally unique file identifier and/or respective file access permissions that differ from a respective globally unique file identifier and/or respective file access permissions in the first metadata; and

replacing the at least a portion of the second metadata includes swapping between the second metadata and the first metadata a respective subset of the second metadata with a respective subset of the first metadata.

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

3. The method of claim 1, wherein the first metadata includes:

(1) a first metadata set created prior to the first operation; and

(2) a second metadata set that includes values of metadata created by the first operation;

wherein the second metadata includes;

(1) a third metadata set created prior to the second operation; and

(2) a fourth metadata set that includes values created by the second operation; and

wherein identifying the two or more file system operations includes matching a filename in the first metadata set and the fourth metadata set.

4. The method of claim 3, wherein the replacing includes swapping a subset of the fourth metadata set with a subset of the second metadata set.

5. The method of claim 3, wherein identifying the two or more file system operations further includes determining that the third metadata set comprises entirely null values.

6. The method of claim 1, wherein the two or more file system operations are identified to comprise an atomic save operation in accordance with a determination that one or more predefined criteria are satisfied, including a criterion that the two or more operations were performed by a same instance of an application.

7. The method of claim 1, further comprising:

synchronizing with a remote server metadata database at least a portion of the first metadata and/or at least a portion of the second metadata.

8. 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.

9. The method of claim 1, further comprising:

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

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

synchronizing the content difference with a remote server content database.

10. The method of claim 1, wherein replacing the second metadata includes updating a subset of the second metadata with a subset of the first metadata such that, after the updating, the second metadata includes two or more of the following from the first metadata:

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

11. 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.

12. A system for preserving metadata associated with an edited file, comprising:

one or more processors;

memory; and

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

obtain log information regarding a plurality of file system operations, wherein the plurality of file system operations include create, delete, and/or rename operations on one or more files in a file system;

identify in the log two or more file system operations that together comprise an atomic save of a particular file of the one or more files;

wherein the two or more file system operations include a first operation involving a first version of the particular file and a second operation involving a second version of the particular file, the second version subsequent to the first version, and

wherein the first version has first metadata and the second version has second metadata, distinct from the first metadata; and

in accordance with the identification of the two or more file system operations as comprising said atomic save, replace at least a portion of the second metadata with at least a portion of the first metadata, including replacing a globally unique file identifier and/or file access permissions;

wherein,

prior to the replacing, the second metadata includes a respective globally unique file identifier and/or respective file access permissions that differ from a respective globally unique file identifier and/or respective file access permissions in the first metadata; and

replacing the at least a portion of the second metadata includes swapping between the second metadata and the first metadata a respective subset of the second metadata with a respective subset of the first metadata.

13. The system of claim 12, wherein the first metadata includes:

(1) a first metadata set created prior to the first operation; and

(2) a second metadata set that includes values of metadata created by the first operation;

wherein the second metadata includes;

(1) a third metadata set created prior to the second operation; and

(2) a fourth metadata set that includes values created by the second operation; and

wherein identifying the two or more file system operations includes matching a filename in the first metadata set and the fourth metadata set.

14. The system of claim 12, wherein the two or more file system operations are identified to comprise an atomic save operation in accordance with a determination that one or more predefined criteria are satisfied, including a criterion that the two or more operations were performed by a same instance of an application.

15. The system of claim 12, wherein the one or more programs further comprise instructions to synchronize with a remote server metadata database at least a portion of the first metadata and/or at least a portion of the second metadata.

16. The system of claim 12, wherein replacing the second metadata includes updating a subset of the second metadata with a subset of the first metadata such that, after the updating, the second metadata includes two or more of the following from the first metadata:

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

17. 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 metadata associated with an edited file, the one or more programs comprising instructions to:

obtain log information regarding a plurality of file system operations, wherein the plurality of file system operations include create, delete, and/or rename operations on one or more files in a file system;

identify in the log two or more file system operations that together comprise an atomic save of a particular file of the one or more files;

wherein the two or more file system operations include a first operation involving a first version of the particular file and a second operation involving a second version of the particular file, the second version subsequent to the first version, and

wherein the first version has first metadata and the second version has second metadata, distinct from the first metadata; and

in accordance with the identification of the two or more file system operations as comprising said atomic save, replace at least a portion of the second metadata with at least a portion of the first metadata, including replacing a globally unique file identifier and/or file access permissions;

wherein,

prior to the replacing, the second metadata includes a respective globally unique file identifier and/or respective file access permissions that differ from a respective globally unique file identifier and/or respective file access permissions in the first metadata; and

replacing the at least a portion of the second metadata includes swapping between the second metadata and the first metadata a respective subset of the second metadata with a respective subset of the first metadata.

18. The non-transitory computer readable storage medium of claim 17, wherein the first metadata includes:

(1) a first metadata set created prior to the first operation; and

(2) a second metadata set that includes values of metadata created by the first operation;

wherein the second metadata includes;

(1) a third metadata set created prior to the second operation; and

(2) a fourth metadata set that includes values created by the second operation; and

wherein identifying the two or more file system operations includes matching a filename in the first metadata set and the fourth metadata set.

19. The non-transitory computer readable storage medium of claim 17, wherein the two or more file system operations are identified to comprise an atomic save operation in accordance with a determination that one or more predefined criteria are satisfied, including a criterion that the two or more operations were performed by a same instance of an application.

20. The non-transitory computer readable storage medium of claim 17, wherein the one or more programs further comprise instructions to synchronize with a remote server metadata database at least a portion of the first metadata and/or at least a portion of the second metadata.

21. The non-transitory computer readable storage medium of claim 17, wherein replacing the second metadata includes updating a subset of the second metadata with a subset of the first metadata such that, after the updating, the second metadata includes two or more of the following from the first metadata:

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