Mobile device with an embedded file system capable of updating file system components

• US 20070288531A1
• Filed: 06/07/2006
• Published: 12/13/2007
• Est. Priority Date: 06/07/2006
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Motta, Giovanni
• Application Number:
  US11/449,259
• Publication Number:
  US 20070288531A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/116 Details of conversion of file system types or formats

Abstract

A file system based OS, such as CRAMFS, is employed in an electronic device. These OS are embedded in some electronic devices and the file systems have particular behavioral characteristics in these electronic devices embedded OS. Updating files in such file system requires the use of heuristics that help manage the update process. For example, heuristics is used to conduct efficient garbage collection in the device as part of the update process, in a preprocessing step.

Claims

1. A method of modifying an electronic device with a file system from a first version V₁ to a second version V₂, the file system comprising a plurality of files, the method comprising:

preprocessing files in version V₁; and

selectively Updating files in version V₁.

2. The method of claim 1 wherein preprocessing comprises:

determining files among the plurality of files that occur in the first version V₁ and not in the second version V₂ and deleting them from the first version V₁ in order to free memory space.

locating files among the plurality of files in version V₁ and in version V₂ that are of the same size and replacing the file from version V₁ without requiring any defragmentation with the corresponding file from version V₂ if the file contents are different; and

finding files in the first version V₁ and second version V₂ wherein the files are shrunk in the second version V₂, and changing them.

defragmenting selectively a portion of the file system for manipulating files from the first version V₁ that are larger in size in the second version V₂ than in the first version V₁.

3. The method of claim 2 wherein the file system comprises a plurality of gaps and wherein defragmenting occurs only when the size of the largest gap among the plurality of gaps currently available is less than the size of the smallest file that currently needs to be updated.

4. The method of claim 2 wherein the file system comprises a plurality of gaps and wherein defragmenting does not occur when the number of available gaps in the plurality of gaps is greater than the number of files to be updated and the size of the new updated version of each of the files is less than a corresponding one of the gaps.

5. A method updating multiple files in a file system wherein a file is selected for updating in a iterative loop if it is expected to cause the smallest possible amount of defragmentation, measured in terms of the occupied bytes moved in order to merge the empty blocks currently available in the file system.

6. A method for managing files in a file system, the file system comprising multiple files and at least one file that needs to be updated, the method comprising:

preprocessing files among those of the at least one file that needs to be updated; and

updating the rest of the at least one file that needs to be updated, if any.

7. The method of managing files according to claim 6 wherein updating comprises selectively employing one of a first fit, a best fit, and a best-pair technique.

8. The method of managing files according to claim 7 wherein the first fit technique comprises sorting the files that need to be updated in decreasing order of size;

and

for each file to be updated after the preprocessing;

determining empty gaps;

modifying the largest file f*_max fitting the largest empty gap g_max and creating a new gap of size g_max−

f_max.

9. The method of managing files according to claim 8 wherein, for all the successful updates the one with the smallest E is selected.

10. The method of managing files according to claim 7 wherein the best fit technique comprises sorting the files that need to be updated in decreasing order;

and

for each file to be updated after the preprocessing;

determining empty gaps;

the largest file f*_max is updated by using the smallest gap g_best having equal or bigger size;

g_best=arg min (g_i−

f*_max); and

creating a new gap a new gap of size g_best−

f*_max.

13. The method of managing files according to claim 7 wherein the best pair technique comprises sorting the files that need to be updated in decreasing order;

and

for each file to be updated after the preprocessing until all files are updated;

determining empty gaps;

a pair comprising a file and a gap (f*_bp,g_bp) is selected so that the remaining portion of the gap g_bp−

f*_bp is minimum among all possible pairs;

converting the file fbp into the file f*_bp and creating a new gap of size g_bp−

f*_bp;

12. The method of updating wherein for all the successful updates the one with the smallest E is selected.

14. The method of updating wherein for all the successful updates the one with the smallest E is selected.