SYMBOLIC LINK BASED PLACEHOLDERS

• US 20180039652A1
• Filed: 08/02/2016
• Published: 02/08/2018
• Est. Priority Date: 08/02/2016
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Nichols, Jack Allen
• Granted Patent: US 12,079,171 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 16/11 File system administration, e.g. details of archiving or snapshots file system backup G06F11/14
• CPC Class Codes: G06F 16/178 Techniques for file synchronisation in file systems
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G06F 16/188 Virtual file systems
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 9/452 Remote windowing, e.g. X-Window System, desktop virtualisation protocols for virtual reality H04L67/131
• CPC Class Codes: G06F 9/50 Allocation of resources, e.g. of the central processing unit [CPU]

Abstract

Symbolic link based placeholders are used for cloud stored data synchronization. To synchronize cloud stored data, placeholders may be implemented as bidirectional symbolic links to a location that has a custom virtual file system (VFS) mounted. When a symbolic link is opened, the operating system may be directed to the custom VFS. The custom VFS may hydrate the file through a synchronization engine, and place the hydrated file at the location of the original symbolic link. The custom VFS may then redirect back to the primary file system of the operating system to allow the operation on the file to complete. Complexity and resource consumption may be reduced by passing placeholder requests instead of all requests through the custom VFS.

Claims

1. A method to provide symbolic link based placeholders for cloud stored data synchronization, the method comprising:

determining a path to a target file from a symbolic link directed to a placeholder virtual file system (VFS);

determining a path to a cloud file from metadata provided by the symbolic link;

deleting the symbolic link;

copying content of the cloud file to the target file; and

copying the path to the target file to a buffer to be returned to a kernel of an operating system.

2. The method of claim 1, further comprising:

redirecting to a primary file system of the operating system to allow an operation on the target file to be completed.

3. The method of claim 2, wherein the primary file system is an operating system specific file system (OSSFS).

4. The method of claim 1, wherein determining the path to the target file from the symbolic link comprises:

retrieving an entity identifier for the target file being represented as a placeholder in the placeholder VFS; and

retrieving a metadata string that describes one or more properties about the target file.

5. The method of claim 4, wherein the one or more properties include a name and a size of the target file.

6. The method of claim 1, further comprising:

implementing the placeholder VFS as a loadable kernel extension.

7. The method of claim 1, further comprising:

mounting the placeholder VFS in an empty, hidden folder within the operating system.

8. The method of claim 1, wherein the placeholder VFS is multithreaded.

9. The method of claim 8, further comprising:

employing a ticket identifier associated with each hydration request to track multithreaded requests.

10. The method of claim 1, wherein determining the path to the cloud file comprises:

downloading the cloud file to a temporary location.

11. A computing device to provide symbolic link based placeholders for cloud stored data synchronization, the computing device comprising:

a communication interface configured to facilitate communication between the computing device and a cloud storage service;

a memory configured to store instructions; and

one or more processors coupled to the memory, the one or more processors, in conjunction with the instructions stored in the memory, are configured to;

receive, at a placeholder virtual file system (VFS), a lookup call from kernel of an operating system of the computing device;

parse a target identified by a symbolic link associated with a target file based on the lookup call;

return a confirmation to the kernel;

in response to receiving one of a read and a write request associated with the target file, transmit a hydration request for the target file to a hydration daemon;

allow the one of the read and write operation to be performed on the hydrated target file; and

transmit a result of the performed operation to a primary file system of the operating system.

12. The computing device of claim 11, wherein the confirmation is a vnode created upon determination of a component name validity associated with the target file and parsing of a path string.

13. The computing device of claim 11, wherein the one or more processors are further configured to:

in response to receiving the one of the read and the write request associated with the target file, determine whether the target file is already hydrated prior to transmitting the hydration request for the target file to the hydration daemon.

14. The computing device of claim 11, wherein the primary file system is an operating system specific file system (OSSFS) that is configured to receive requests for operations on files and symbolic links, and forward the requests for the symbolic links to a target at the placeholder VFS.

15. The computing device of claim 11, wherein files represented by the placeholder VFS are abstractions of files managed by the cloud storage service.

16. A physical computer-readable memory device with instructions stored thereon to provide symbolic link based placeholders for cloud stored data synchronization, the instructions comprising:

determining a path to a target file from a symbolic link bi-directionally directed to a placeholder virtual file system (VFS);

determining a path to a cloud file from metadata provided by the symbolic link;

copying content of the cloud file to the target file;

copying the path to the target file to a buffer to be returned to a kernel of an operating system; and

redirecting to a primary file system of the operating system to allow an operation on the target file to be completed.

17. The computer-readable memory device of claim 16, wherein determining the path to the cloud file comprises:

streaming the cloud file from a network location.

18. The computer-readable memory device of claim 16, wherein the operation includes a VFSOP_LOOKUP operation configured to pass a component name parameter and return a vnode in response to validation of a component name and parsing of a path string.

19. The computer-readable memory device of claim 16, wherein the placeholder VFS is configured to transmit a hydration request to a hydration daemon upon determining the target file is not hydrated.

20. The computer-readable memory device of claim 19, wherein the instructions further comprise:

enabling one or more of a read operation, a write operation, and a read/write operation on the hydrated target file upon completion of the hydration.