Extending cluster allocations in an extensible file system

• US 8,364,732 B2
• Filed: 01/13/2011
• Issued: 01/29/2013
• Est. Priority Date: 05/23/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Pudipeddi, Ravisankar V., Ghotge, Vishal V., Havewala, Sarosh C., Zbikowski, Mark J., Goebel, David A., Thind, Revinder S.
• Primary Examiner(s): AL HASHEMI, SANA A
• Application Number:
  US13/006,088
• Publication Number:
  US 20110113078A1
• Time in Patent Office: 747 Days
• Field of Search: 707/791, 707/793, 707/795, 707/954, 707/955, 707/960, 707/966
• US Class Current: 707/966
• 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 16/1727 Details of free space management performed by the file system saving storage space on storage systems G06F3/0608; management of blocks in storage devices G06F3/064
• CPC Class Codes: G06F 16/18 File system types
• CPC Class Codes: G06F 16/1847 specifically adapted to static storage, e.g. adapted to flash memory or SSD
• CPC Class Codes: G06F 16/2237 Vectors, bitmaps or matrices
• CPC Class Codes: G06F 16/2291 User-Defined Types; Storage management thereof
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: G06F 16/285 Clustering or classification
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

An extensible file system format for portable storage media is provided. The extensible file system format includes the specification of primary and secondary directory entry types that may be custom defined. The primary and secondary directory entry types can be further classified as critical and benign directory entries. The directory entry types can define whether a cluster chain corresponding to a file can be contiguously allocated.

Claims

1. A method, comprising:

obtaining a request to delete a plurality of contiguously allocated clusters of a storage media, each cluster of the plurality of contiguously allocated clusters having a corresponding allocation bitmap entry in an allocation bitmap, the allocation bitmap indicating cluster availability within the storage media; and

clearing each allocation bitmap entry corresponding to the plurality of contiguously allocated clusters to indicate data associated with the plurality of contiguously allocated clusters has been deleted, each allocation bitmap entry having been cleared without traversing a file allocation table associated with the storage media.

2. The method of claim 1, further comprising:

obtaining starting cluster information and a cluster chain size associated with the plurality of contiguously allocated clusters; and

identifying each allocation bitmap entry using the obtained starting cluster information and cluster chain size.

3. The method of claim 1, further comprising:

determining whether the clusters are contiguously allocated.

4. The method of claim 3 wherein determining whether the clusters are contiguously allocated includes determining whether a contiguous allocation indicium associated with the plurality of clusters indicates that the plurality of clusters is currently contiguously allocated.

5. The method of claim 4 wherein the contiguous allocation indicium is stored in a primary directory entry associated with the plurality of contiguously allocated clusters.

6. The method of claim 4 wherein the contiguous allocation indicium is stored in a secondary directory entry associated with the plurality of contiguously allocated clusters.

7. A computing device comprising computer-executable components that, when executed, cause the computing device to perform operations comprising:

obtaining a request to delete a plurality of contiguously allocated clusters of a storage media, each cluster of the plurality of contiguously allocated clusters having a corresponding allocation bitmap entry in an allocation bitmap, the allocation bitmap indicating cluster availability within the storage media for a file system;

obtaining starting cluster information and a cluster chain size associated with the plurality of contiguously allocated clusters;

identifying each allocation bitmap entry using the obtained starting cluster information and cluster chain size; and

modifying each allocation bitmap entry corresponding to the plurality of contiguously allocated clusters to indicate to the file system that data stored in the plurality of contiguously allocated clusters has been deleted, each allocation bitmap entry being modified without traversing a file allocation table of the file system.

8. The computing device of claim 7 wherein the computer-executable components, when executed, cause the computing device to perform operations further comprising:

determining whether a contiguous allocation indicium associated with the plurality of clusters indicates that the plurality of clusters is currently contiguously allocated.

9. The computing device of claim 8 wherein the contiguous allocation indicium is stored in a primary directory entry of the file system associated with the plurality of contiguously allocated clusters.

10. The computing device of claim 8 wherein the contiguous allocation indicium is stored in a secondary directory entry of the file system associated with the plurality of contiguously allocated clusters.

11. One or more computer storage media including computer-executable instructions that, when executed, perform operations comprising:

obtaining a request to delete a plurality of contiguously allocated clusters of a storage media, each cluster of the plurality of contiguously allocated clusters having a corresponding allocation bitmap entry in an allocation bitmap, the allocation bitmap indicating cluster availability within the storage media for a file system;

obtaining starting cluster information and a cluster chain size associated with the plurality of contiguously allocated clusters;

identifying each allocation bitmap entry using the obtained starting cluster information and cluster chain size; and

modifying each allocation bitmap entry corresponding to the plurality of contiguously allocated clusters to indicate to the file system that the plurality of contiguously allocated clusters are available, each allocation bitmap entry being modified without traversing a file allocation table of the file system.

12. The one or more computer storage media of claim 11 wherein the computer-executable instructions, when executed, perform operations further comprising:

determining whether a contiguous allocation flag associated with the plurality of clusters indicates that the plurality of clusters is currently contiguously allocated.

13. The one or more computer storage media of claim 12 wherein the contiguous allocation flag is stored in a primary directory entry of the file system associated with the plurality of contiguously allocated clusters.

14. The one or more computer storage media of claim 12 wherein the contiguous allocation flag is stored in a secondary directory entry of the file system associated with the plurality of contiguously allocated clusters.