On-demand block-level file system streaming to remote desktops

• US 8,112,505 B1
• Filed: 03/12/2010
• Issued: 02/07/2012
• Est. Priority Date: 10/20/2009
• Status: Active Grant

• Current Assignee: Omnissa, LLC
• Original Assignee: Wanova Technologies Ltd. (Broadcom, Inc.)
• Inventors: Ben-Shaul, Israel, Glixman, Shahar, Zamir, Tal
• Primary Examiner(s): Luu, Le
• Application Number:
  US12/723,550
• Time in Patent Office: 697 Days
• Field of Search: 709/217, 709/218, 709/219, 709/246, 711/100, 711/130, 711/145, 726/1, 398/45, 707/704, 707/770, 705/400
• US Class Current: 709/219
• CPC Class Codes: G06F 16/1767 Concurrency control, e.g. optimistic or pessimistic approaches

Abstract

Techniques are provided for desktop streaming over wide area networks. In one embodiment, a computing device comprises logic that is configured to intercept file open requests for files stored in a file system, where at least some of the files in the file system may have not yet been fully downloaded. In response to a request to open a file, the logic is configured to modify a first sharing mode specified therein and to open the file in a read-write sharing mode that allows other processes to open the file. While one or more blocks of the file are being downloaded or written into the file, the logic is configured to check whether a second sharing mode received in a subsequent request to open the file is compatible with the first sharing mode. If the second sharing mode is not compatible with the first sharing mode, the logic is configured to deny the subsequent request even though in the file system the file is opened in the read-write sharing mode.

Claims

1. A computing device comprising:

one or more processors;

one or more storage media coupled to the one or more processors;

logic stored in the one or more storage media and executable by the one or more processors, wherein the logic is configured to cause the one or more processors to;

receive, from a first process of the computing device, a first request to open a file in a file system of the computing device, wherein the first request to open the file specifies a first sharing mode that precludes other processes of the computing device from opening the file, wherein at least one block from the file has not yet been downloaded to the computing device;

modify, in response to the first request, the first sharing mode to a read-write sharing mode that allows other processes to open the file, and open the file in the read-write sharing mode;

receive one or more blocks from the file and write the one or more blocks into the file;

while the one or more blocks are being received or written into the file, receive a second request to open the file from a second process of the computing device, wherein the second request specifies a second sharing mode;

check the second sharing mode for compatibility with the first sharing mode;

deny the second request when the second sharing mode is not compatible with the first sharing mode even though in the file system the file is opened in the read-write sharing mode.

2. The computing device of claim 1, wherein the logic is further configured to notify the first process that the file is opened in the first sharing mode even though in the file system the file is opened in the read-write sharing mode.

3. The computing device of claim 1, wherein the logic is further configured to:

when the second sharing mode is compatible with the first sharing mode, modify the second sharing mode to the read-write sharing mode and open the file in the read-write sharing mode in response to the second request;

notify the second process that the file is opened in the second sharing mode even though in the file system the file is opened in the read-write sharing mode.

4. The computing device of claim 1, wherein the logic is further configured to:

predict that a lock on a byte-range in a particular block from the file will be needed;

send a third request to download the particular block from the file.

5. The computing device of claim 1, wherein the first request to open the file needs a lock on a byte-range in a particular block from the file that has not yet been downloaded to the computing device;

wherein the logic is further configured to;

in response to the first request, maintain the lock on the byte-range in the particular block from the file, but without propagating the lock to the file system;

while the particular block is being received or written into the file, check the lock for compatibility with any subsequent requests that need locks on the byte-range in the particular block from the file;

deny those subsequent requests which are not compatible with the lock on the byte-range in the particular block from the file.

6. The computing device of claim 1, wherein the logic is further configured to:

intercept one or more subsequent requests for the one or more blocks from the file;

block the one or more subsequent requests until the one or more blocks have been written into the file.

7. The computing device of claim 1, wherein the logic is further configured to:

collect first information indicating access patterns to a set of blocks from the file;

receive a third request for a particular block from the set of blocks;

in response to the third request, based on the first information, predict which other blocks from the set of blocks are likely to be requested;

send a fourth request to download the other blocks from the set of blocks prior to requests for the other blocks.

8. The computing device of claim 1, wherein the logic is further configured to intercept calls to access files in the file system and to continuously collect first information indicating the usage of the files.

9. The computing device of claim 8, wherein the logic is further configured to:

based on the first information, generate a list of files that identifies those files that were accessed during one or more previous reboots of the computing device;

send the list of files to a data center that is configured to store a desktop image for the computing device, wherein the list of files is used to segment a collection of files included the desktop image into a prefetch set, a streaming set, and a leave-behind set, wherein;

the prefetch set includes a smallest subset of files, in the collection of files, that is needed to boot up the computing device without requiring retrieval of additional files;

the streaming set includes those files, in the collection of files, that are to be downloaded to the computing device after the computing device has booted up;

the leave-behind set includes those files, in the collection of files, that are to be downloaded to the computing device when specifically requested by the computing device.

10. The computing device of claim 8, wherein:

the first information indicates one or more of file and directory creation operations, file and directory rename operations, and file close operations;

the logic is further configured to;

store the first information as entries in an in-memory queue that is allocated in volatile memory;

periodically traverse the in-memory queue and remove any duplicate entries from the in-memory queue.

11. The computing device of claim 1, wherein the logic is further configured to:

indicate, to file requestors executing on the computing device, that all files of the file system are stored on the computing device even though not all files have been fully downloaded to the computing device, wherein the file system stores metadata for those files that have not yet been downloaded, wherein the metadata includes file names, file system structure, file sizes, file attributes, and access control lists (ACLs), and wherein the file requestors include an operating system (OS) process and a user application process;

receive a third request for a particular file;

determine that the particular file is associated with a particular identifier in the file system, wherein the particular identifier indicates that the particular file has not yet been downloaded;

block the third request and cause the particular file to be downloaded with a highest priority;

after at least a portion of the particular file has been downloaded, unblock the third request and in response thereto provide a file handle to the particular file.

12. The computing device of claim 1, wherein the logic is further configured to:

when a file has not yet been downloaded to the computing device, set an offline-bit attribute for the file in file system metadata that corresponds to the file.

13. A computer-readable non-transitory storage medium storing one or more sequences of instructions comprising instructions which, when executed by one or more processors, cause the one or more processors to:

receive, from a first process of the computing device, a first request to open a file in a file system of the computing device, wherein the first request to open the file specifies a first sharing mode that precludes other processes of the computing device from opening the file, and wherein at least one block from the file has not yet been downloaded to the computing device;

modify, in response to the first request, the first sharing mode to a read-write sharing mode that allows other processes to open the file, and open the file in the read-write sharing mode;

receive one or more blocks from the file and write the one or more blocks into the file;

while the one or more blocks are being received or written into the file, receive a second request to open the file from a second process of the computing device, wherein the second request specifies a second sharing mode;

check the second sharing mode for compatibility with the first sharing mode;

deny the second request when the second sharing mode is not compatible with the first sharing mode even though in the file system the file is opened in the read-write sharing mode.

14. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to notify the first process that the file is opened in the first sharing mode even though in the file system the file is opened in the read-write sharing mode.

15. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

when the second sharing mode is compatible with the first sharing mode, modify the second sharing mode to the read-write sharing mode and open the file in the read-write sharing mode in response to the second request;

notify the second process that the file is opened in the second sharing mode even though in the file system the file is opened in the read-write sharing mode.

16. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

predict that a lock on a byte-range in a particular block from the file will be needed;

send a third request to download the block from the file.

17. The computer-readable non-transitory storage medium of claim 13, wherein the first request to open the file needs a lock on a byte-range in a particular block from the file that has not yet been downloaded to the computing device, and wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

in response to the first request, maintain the lock on the byte-range in the particular block from the file, but without propagating the lock to the file system;

while the particular block is being received or written into the file, check the lock for compatibility with any subsequent requests that need locks on the byte-range in the particular block from the file;

deny those subsequent requests which are not compatible with the lock on the byte-range in the particular block from the file.

18. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

intercept one or more subsequent requests for the one or more blocks from the file;

block the one or more subsequent requests until the one or more blocks have been written into the file.

19. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

collect first information indicating access patterns to a set of blocks from the file;

receive a third request for a particular block from the set of blocks;

in response to the third request, based on the first information, predict which other blocks from the set of blocks are likely to be requested;

send a fourth request to download the other blocks from the set of blocks prior to requests for the other blocks.

20. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to intercept calls to access files in the file system and to continuously collect first information indicating the usage of the files.

21. The computer-readable non-transitory storage medium of claim 20, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

based on the first information, generate a list of files that identifies those files that were accessed during one or more previous reboots of the computing device;

send the list of files to a data center that is configured to store a desktop image for the computing device, wherein the list of files is used to segment a collection of files included the desktop image into a prefetch set, a streaming set, and a leave-behind set, wherein;

the prefetch set includes a smallest subset of files, in the collection of files, that is needed to boot up the computing device without requiring retrieval of additional files;

the streaming set includes those files, in the collection of files, that are to be downloaded to the computing device after the computing device has booted up;

the leave-behind set includes those files, in the collection of files, that are to be downloaded to the computing device when specifically requested by the computing device.

22. The computer-readable non-transitory storage medium of claim 20, wherein:

the first information indicates one or more of file and directory creation operations, file and directory rename operations, and file close operations;

the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to;

store the first information as entries in an in-memory queue that is allocated in volatile memory;

periodically traverse the in-memory queue and remove any duplicate entries from the in-memory queue.

23. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

indicate, to file requestors executing on the computing device, that all files of the file system are stored on the computing device even though not all files have been fully downloaded to the computing device, wherein the file system stores metadata for those files that have not yet been downloaded, wherein the metadata includes file names, file system structure, file sizes, file attributes, and access control lists (ACLs), and wherein the file requestors include an operating system (OS) process and a user application process;

receive a third request for a particular file;

determine that the particular file is associated with a particular identifier in the file system, wherein the particular identifier indicates that the particular file has not yet been downloaded;

block the third request and cause the particular file to be downloaded with a highest priority;

after at least a portion of the particular file has been downloaded, unblock the third request and in response thereto provide a file handle to the particular file.

24. The computer-readable non-transitory storage medium of claim 13, wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to:

when a file has not yet been downloaded to the computing device, set an offline-bit attribute for the file in file system metadata that corresponds to the file.