Extending cluster allocations in an extensible file system

Patent metadata

Field	Value
Publication number	US-9558223-B2
Application number	US-201514815076-A
Country	US
Kind code	B2
Filing date	Jul 31, 2015
Priority date	May 23, 2006
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

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.

First claim

What is claimed:

1. A method, comprising:
obtaining a request for an extension of a plurality of clusters, the plurality of clusters comprising a cluster chain of two or more clusters stored contiguously, the extension comprising an allocation of one or more additional clusters to the cluster chain;
allocating an entry in a file allocation table for each of the clusters of the continguous cluster chain;
indicating that the file allocation table entries exist for the clusters of the continguous cluster chain;
allocating an entry in the file allocation table for each of the additional clusters of the extension; and
updating an allocation bitmap to indicate the allocation of the clusters for the plurality of clusters and the extension.

2. The method of claim 1 , the indicating comprising clearing a flag in a directory entry associated with the cluster chain, the flag, when set, indicating that the clusters of the cluster chain associated with the directory entry are stored contiguously.

3. The method of claim 1 , further comprising, prior to allocating an entry in the file allocation table for each of the clusters of the contiguous cluster chain, determining from the allocation bitmap that the extension and the plurality of clusters of the contiguous cluster chain are not contiguously allocatable.

4. The method of claim 2 , wherein before obtaining the request for the extension of the plurality of clusters, the flag indicates the plurality of clusters are contiguously allocated.

5. The method of claim 2 , wherein after clearing the flag, the flag indicates the plurality of clusters and the extension are not contiguously allocated.

6. A computer-readable storage medium on which computer-executable instructions are stored which, when executed by a computing device, cause the computing device to perform operations comprising:
obtaining a request for an extension of a plurality of clusters, the plurality of clusters comprising a cluster chain of two or more clusters stored contiguously, the extension comprising an allocation of one or more additional clusters to the cluster chain;
allocating an entry in a file allocation table for each of the clusters of the continguous cluster chain;
indicating that the file allocation table entries exist for the clusters of the continguous cluster chain;
allocating an entry in the file allocation table for each of the additional clusters of the extension; and
updating an allocation bitmap to indicate the allocation of the clusters for the plurality of clusters and the extension.

7. The computer-readable storage medium of claim 6 , the indicating comprising clearing a flag in a directory entry associated with the cluster chain, the flag, when set, indicating that the clusters of the cluster chain associated with the directory entry are stored contiguously.

8. The computer-readable storage medium of claim 6 , wherein the computer-executable instructions further cause the computing device to, prior to allocating an entry in the file allocation table for each of the clusters of the contiguous cluster chain, determine from the allocation bitmap that the extension and the plurality of clusters of the contiguous cluster chain are not contiguously allocatable.

9. The computer-readable storage medium of claim 7 , wherein before the computing device obtains the request for the extension of the plurality of clusters, the flag indicates the plurality of clusters are contiguously allocated.

10. The computer-readable storage medium of claim 7 , wherein after clearing the flag, the flag indicates the plurality of clusters and the extension are not contiguously allocated.

11. A computing device, comprising:
one or more computer-readable storage media on which computer-executable instructions are stored which, when executed by the computing device, cause the computing device to perform operations comprising:
obtaining a request for an extension of a plurality of clusters, the plurality of clusters comprising a cluster chain of two or more clusters stored contiguously, the extension comprising an allocation of one or more additional clusters to the cluster chain;
allocating an entry in a file allocation table for each of the clusters of the continguous cluster chain;
indicating that the file allocation table entries exist for the clusters of the continguous cluster chain;
allocating an entry in the file allocation table for each of the additional clusters of the extension; and
updating an allocation bitmap to indicate the allocation of the clusters for the plurality of clusters and the extension.

12. The computing device of claim 11 , the indicating comprising clearing a flag in a directory entry associated with the cluster chain, the flag, when set, indicating that the clusters of the cluster chain associated with the directory entry are stored contiguously.

13. The computing device of claim 11 , wherein the computer-executable instructions further cause the computing device to, prior to allocating an entry in the file allocation table for each of the clusters of the contiguous cluster chain, determine from the allocation bitmap that the extension and the plurality of clusters of the contiguous cluster chain are not contiguously allocatable.

14. The computing device of claim 12 , wherein before the computing device obtains the request for the extension of the plurality of clusters, the flag indicates the plurality of clusters are contiguously allocated.

15. The computing device of claim 12 , wherein after clearing the flag, the flag indicates the plurality of clusters and the extension are not contiguously allocated.

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Pudipeddi Ravisankar V
• Ghotge Vishal V
• Havewala Sarosh C
• Thind Ravinder S
• Zbikowski Mark J
• Goebel David A

Classifications

• G06F16/1727

  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 title

• G06F16/285

  Clustering or classification · CPC title

• G06F3/0607

  by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device · CPC title

• G06F3/0643 Primary

  Management of files · CPC title

• G06F3/067

  Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS] · CPC title