File access method and system thereof

Patent metadata

Field	Value
Publication number	US-9569447-B2
Application number	US-201314075757-A
Country	US
Kind code	B2
Filing date	Nov 8, 2013
Priority date	Nov 8, 2013
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

Several systems and methods for accessing files stored in a storage device are disclosed. In an embodiment, the method includes accessing a file allocation table (FAT) in a computer file system associated with the storage device. The FAT includes a plurality of cluster addresses corresponding to a plurality of clusters allocated to a file stored in the storage device. A cluster address is read to identify a location of a next cluster. One or more bits in the cluster address are read to determine a presence of a signature value indicating allocation of a set of contiguous clusters from among the plurality of clusters. A number of contiguous clusters is computed based on a pre-determined number of consecutive cluster addresses succeeding the cluster address if the signature value is present. The set of contiguous clusters are read from the storage device based on the computed number of contiguous clusters.

First claim

What is claimed is:

1. A file access method comprising:
accessing a file allocation table (FAT) in a computer file system associated with a storage device, the FAT comprising a plurality of cluster addresses corresponding to a plurality of clusters allocated to a file stored in the storage device;
reading a cluster address from among the plurality of cluster addresses to identify a location of a next cluster from among the plurality of clusters, the cluster address being configured by a plurality of bits, wherein one or more bits from among the plurality of bits are read to determine a presence of a signature value and the presence of the signature value being indicative of an allocation of a set of contiguous clusters from among the plurality of clusters;
computing a number of contiguous clusters in the set of contiguous clusters based on the determination that the signature value is present in the cluster address, the number of contiguous clusters computed based on a pre-determined number of consecutive cluster addresses succeeding the cluster address; and
reading the set of contiguous clusters from the storage device based on the computed number of contiguous clusters.

2. The method of claim 1 , wherein the computer file system is a FAT32 file system and wherein each cluster address from among the plurality of cluster addresses comprises 32 bits.

3. The method of claim 2 , wherein the presence of the signature value is determined based on a pre-specified bit configuration formed by four most significant bits from among 32 bits configuring the cluster address.

4. The method of claim 1 , wherein the pre-determined number of consecutive cluster addresses is four, and wherein the number of contiguous clusters is computed based on four cluster addresses succeeding the cluster address.

5. The method of claim 4 , further comprising: concatenating four most significant bits associated with each of the four cluster addresses to generate a 16-bit value indicative of the number of contiguous clusters allocated to the file.

6. The method of claim 1 , wherein the pre-determined number of consecutive cluster addresses is seven, and wherein the number of contiguous clusters is computed based on seven cluster addresses succeeding the cluster address.

7. The method of claim 6 , further comprising: concatenating four most significant bits associated with each of the seven consecutive cluster addresses to generate a 28-bit value indicative of the number of contiguous clusters allocated to the file.

8. The method of claim 1 , further comprising: determining an ending cluster associated with the set of contiguous clusters based on the computed number of contiguous clusters in order to facilitate a reading of the contiguous clusters allocated to the file.

9. The method of claim 1 , further comprising: reading one or more cluster addresses from the FAT for identifying clusters following the set of contiguous clusters, wherein a presence of the signature value is determined for each reading of the one or more cluster addresses in order to identify an allocation of another set of contiguous clusters from among remaining clusters in the plurality of clusters allocated to the file.

10. The method of claim 9 , further comprising:
determining if the plurality of clusters allocated to the file is modified; and
updating one or more signature values and corresponding number of contiguous clusters if the plurality of clusters allocated to the file is determined to be modified.

11. A file access system comprising:
a storage device configured to store a plurality of files;
a memory configured to store a set of instructions; and
a processing module communicatively associated with the storage device and the memory, the processing module configured to execute the set of instructions to access a file from among the plurality of files by:
accessing a file allocation table (FAT) in a computer file system associated with the storage device, the FAT comprising a plurality of cluster addresses corresponding to a plurality of clusters allocated to the file stored in the storage device;
reading a cluster address from among the plurality of cluster addresses to identify a location of a next cluster from among the plurality of clusters, the cluster address being configured by a plurality of bits, wherein one or more bits from among the plurality of bits are read to determine a presence of a signature value and the presence of the signature value being indicative of an allocation of a set of contiguous clusters from among the plurality of clusters;
computing a number of contiguous clusters in the set of contiguous clusters based on the determination that the signature value is present in the cluster address, the number of contiguous clusters computed based on a pre-determined number of consecutive cluster addresses succeeding the cluster address; and
reading the set of contiguous clusters from the storage device based on the computed number of contiguous clusters.

12. The system of claim 11 , wherein the computer file system is a FAT32 file system and wherein each cluster address from among the plurality of cluster addresses comprises 32 bits.

13. The system of claim 12 , wherein the presence of the signature value is determined based on a pre-specified bit configuration formed by four most significant bits from among 32 bits configuring the cluster address.

14. The system of claim 11 , wherein the pre-determined number of consecutive cluster addresses is four, and wherein the processing module is further configured to concatenate four most significant bits associated with each of the four consecutive cluster addresses to generate a 16-bit value indicative of the number of contiguous clusters allocated to the file.

15. The system of claim 11 , wherein the pre-determined number of consecutive cluster addresses is seven, and wherein the processing module is further configured to concatenate four most significant bits associated with each of the seven consecutive cluster addresses to generate a 28-bit value indicative of the number of contiguous clusters allocated to the file.

16. A non-transitory computer-readable medium storing a set of instructions that when executed cause a computer to perform a file access method, the method comprising:
accessing a file allocation table (FAT) in a computer file system associated with a storage device, the FAT comprising a plurality of cluster addresses corresponding to a plurality of clusters allocated to a file stored in the storage device;
reading a cluster address from among the plurality of cluster addresses to identify a location of a next cluster from among the plurality of clusters, the cluster address being configured by a plurality of bits, wherein one or more bits from among the plurality of bits are read to determine a presence of a signature value and the presence of the signature value being indicative of an allocation of a set of contiguous clusters from among the plurality of clusters;
computing a number of contiguous clusters in the set of contiguous clusters based on the determination that the signature value is present in the cluster address, the number of contiguous clusters computed based on a pre-determined number of consecutive cluster addresses succeeding the cluster address; and
reading the set of contiguous clusters from the storage device based on the computed number of contiguous clusters.

17. The non-transitory computer-readable medium of claim 16 , wherein the computer file system is a FAT32 file system and wherein each cluster address from among the

Assignees

• Texas Instruments Inc

Inventors

• Srinivas Madan
• Raju Veeramanikandan
• Munegowda Keshava

Classifications

• G06F16/13 Primary

  File access structures, e.g. distributed indices (arrangements of input from, or output to, record carriers G06F3/06) · CPC title

• G06F16/152 Primary

  using file content signatures, e.g. hash values · CPC title

• G06F16/134

  Distributed indices · CPC title

• G06F16/183

  Provision of network file services by network file servers, e.g. by using NFS, CIFS (network file access protocols H04L67/1097) · CPC title

• G06F17/30091 Primary

  Physics · mapped topic