NAMING PROTOCOL FOR EXTENSIBLE FILE SYSTEMS
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.
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This application is a divisional of application Ser. No. 11/229,485, entitled EXTENSIBLE FILE SYSTEM, and filed on Sep. 16, 2005, which in turn claims the benefit of Provisional Application No. 60/637,407, entitled FILE SYSTEM FORMAT FOR PORTABLE MEDIA, and filed on Dec. 17, 2004.
BACKGROUNDGenerally described, there are a number of portable computing devices, such as digital still cameras, digital video cameras, media players, mobile phones, mobile computing devices, personal digital assistants, and the like that maintain data on a storage media, such as a portable storage media. The continued development of more complex portable computing devices and larger storage capacity portable storage media places a greater demand for flexibility on the file system format used on the storage media. Current file system format approaches can become deficient in that they may provide adequate flexibility for increasing storage size capacities and/or storage media applications.
SUMMARYAn 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.
In accordance with an aspect of the present invention, a computer-readable medium having computer-executable components for storing data is provided. The computer-readable components can include a boot parameters component for specifying boot parameters for a file system. The computer-readable components also include a file allocation table component for defining a file allocation table associated with the file system. Additionally, the computer-readable components include a primary directory entry component for specifying data in a root directory of the file system. Still further, the computer-readable components include at least one secondary entry component corresponding to the primary directory entry component. The secondary entry component defines defining meta data associated with the primary directory entry component. The primary and secondary directory entry components can be further classified as critical or benign.
In accordance with another aspect of the present invention, a computer-readable medium having computer-executable components for storing data is provided. The computer-readable components include a boot parameters component for specifying boot parameters for a file system. The computer-readable components also include a file allocation table component for defining a file allocation table associated with the file system. Still further, the computer-readable components include a root directory component for specifying data in a root directory of the file system. Additionally, the computer-readable components include at least extensible one meta data component corresponding to the root directory entry component. The meta data component defines meta data associated with the root directory component.
In an illustrative embodiment, a file system will not mount a volume for a critical primary or root directory entry that is not recognized. The file system can ignore benign primary directory entries, critical secondary directory entries and benign secondary directory entries that are not recognized.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
Generally described, the present invention relates to an extensible file system format and various processes associated with the extensible file system format. In an illustrative embodiment, the extensible file system format corresponds to an extensible file system format for portable storage media and various processes associated with the extensible file system format on the portable storage media. Although the present invention will be described with regard to a portable storage media file system format, one skilled in the relevant art will appreciate that the disclosed embodiments are illustrative in nature and should not be construed as limiting. Additionally, one skilled in the relevant art will appreciate that the data structures and data layouts used in the illustrative examples may require additional information related to performance, security, and the like.
In an illustrative embodiment, the mobile computing device 102 may be in communication with other computing devices for collecting/exchanging data to be stored on the portable storage media 104. With reference to
With reference now to
The volume layout 200 also includes an extensible parameters component, designated as OEM parameters 204, that define various additional data structures used in conjunction with the file system. In an illustrative embodiment, an original equipment manufacture (OEM) may specify various extensible data structures, such as performance parameters for a storage medium, that can be defined at time of manufacture. The volume layout 200 can further include a file allocation table component 206 that defines file and directory allocations. In an illustrative embodiment, each entry in the file allocation table component 206 corresponds to a 32-bit entry that represents an allocated cluster, an unallocated cluster or an unusable cluster. The volume layout 200 can still further include series of file data components 208A-208X that correspond to the data stored according to the file system format. Various data structures for defining a portion of the file data components 208A-208X will be defined with regard to
Turning now to
With continued reference to
In a manner similar to primary directory entries 302, secondary directory entries 304 may also be further classified as critical secondary directory entries 310 and benign secondary directory entries 312. As described above, the critical secondary directory entries 310 and benign secondary directory entries 312 are associated with a benign primary directory entry and extend the metadata associated with the primary directory entry. Both the critical secondary directory entries 310 and the benign secondary directory entries 312 can be associated with another cluster chain the volume.
To mount a corresponding to the extensible file system format, the file system implements a mount volume procedure. In an illustrative embodiment, the mount volume procedure attempts to a look at a version number for the volume. If the version number is not understood (e.g., the version number is higher), the volume will not be mounted. During a normal directory enumeration, any critical primary directory entries not known by the file system will prevent the volume from being mounted. Thereafter, various user-initiated processes, such as a file open, will cause the file system to enumerate the secondary directory entries. If the critical secondary directory entries 310 are not known by a file system, the entire directory entry will be skipped. Additionally, if benign secondary directory entries 312 are not known by the file system, the particular unknown benign secondary directory entry will be ignored.
With reference now to
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With reference now to
With reference to
With reference to
In an illustrative embodiment, a benign primary directory entry and/or secondary directory entries may be associated with access control list (ACL) information.
With reference now to
At decision block 1108, a test is conducted to determine whether the target hash value matches the current directory entry hash value. If they do not match, the routine 1100 returns to block 1106 (until all the directory entries have been examined. If the hash values match at decision block 1108, at block 1110, the file system obtains the full file name for the potentially matching directory entry. An illustrative directory entry type for storing directory entry full file names is described above with regard to data components 600 (
In accordance with an aspect of the present invention, various additional functionality may be added through the specification of specific directory types. For example, name streams may be supported by specifying a name stream directory entry. Additionally, on-disk encryption may also be supported through the utilization of specific encryption algorithms and key exchanges. Still further, time zone conversions may be associated with directory entries to automatically convert a current time zone with a time zone with the directory entry was made.
While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.
Claims
1. In a computer-readable medium having computer-readable components corresponding to a plurality of directory entries, wherein at least a subset of the directory entries correspond to data name directory entries, a method for processing directory entries comprising:
- obtaining a target file name for a new directory entry;
- generating an identifier for the target file name;
- for each data name directory entry in the plurality of directory entries, comparing the identifier for the target file name with an identifier for a file name of each data name directory entry; and
- selecting the target file name for the new directory entry if the identifier for the target file name does not match an identifier for the file name for any of the data name directory entries.
2. The method as recited in claim 1, wherein generating an identifier for the target file name includes generating a hash of the target file name and wherein comparing the identifier for the target file name with an identifier for the file name of each directory entry includes comparing the hash of the target file name with a file name hash stored in the data name directory entry.
3. The method as recited in claim 1 further comprising:
- determining that the identifier for the target file name matches an identifier for at least one file name in a data name directory entry;
- obtaining a full file name of a matching data name directory entry;
- comparing the target file name with the full file of the matching data name directory entry; and
- selecting the target file for data if the target file name does not match the full file name of the matching data name directory entry.
4. The method as recited in claim 3 further comprising rejecting the target file name for data if the target file name matches the full file name of the matching data name directory entry.
5. The method as recited in claim 3 further comprising identifying the target file name as matching an existing directory entry if the target file name matches the full file name of each directory entry.
6. The method as recited in claim 1, wherein obtaining a target file name includes obtaining a file creation request.
7. The method as recited in claim 1, wherein obtaining a target file name includes obtaining a file modification request.
8. In a computer-readable medium having computer-readable components corresponding to a plurality of directory entries, wherein at least a subset of the directory entries correspond to data name directory entries including a full file name and a file name identifier, a method for processing directory entries comprising:
- obtaining a target file name for a new directory entry;
- generating an identifier for the target file name;
- for each data name directory entry in the plurality of directory entries, comparing the identifier for the target file name with a file name identifier from the data name directory entry; and
- generating a new data name directory entry for the target file name if the identifier for the target file name does not match file name identifier for any of the data name directory entries.
9. The method as recited in claim 8, wherein generating an identifier for the target file name includes generating a hash of the target file name and wherein comparing the identifier for the target file name with an identifier for the file name of each directory entry includes comparing the hash of the target file name with a file name hash stored in the data name directory entry.
10. The method as recited in claim 8 further comprising:
- determining that the identifier for the target file name matches at least one file name identifier in the data name directory entries;
- obtaining a full file name of one or more matching data name directory entries;
- comparing the target file name with the full file of the matching data name directory entries; and
- generating a new data name directory entry for the target file name if the identifier for the target file name does not match file name identifier for any of the data name directory entries.
11. The method as recited in claim 10 further comprising rejecting the target file name for data if the target file name matches the full file name of the matching data name directory entries.
12. The method as recited in claim 10 further comprising identifying the target file name as matching an existing directory entry if the target file name matches the full file name of each directory entries.
13. The method as recited in claim 9, wherein obtaining a target file name includes obtaining a file creation request.
14. The method as recited in claim 9, wherein generating a new data name directory entry for the target file name if the identifier for the target file name does not match file name identifier for any of the data name directory entries includes generating a data name directory entry including the target file name and the identifier of the target file name.
15. In a computer-readable medium having computer-readable components corresponding to a plurality of directory entries, wherein at least a subset of the directory entries correspond to data name directory entries, a method for processing directory entries comprising:
- obtaining a target file name for a new directory entry;
- generating a hash for the target file name;
- for each data name directory entry in the plurality of directory entries, comparing the hash for the target file name with a hash for a file name of each data name directory entry; and
- selecting the target file for the new directory entry if the identifier for the target file name does matches an identifier for the file name for any of the data name directory entries.
- generating a new data name directory entry for the target file name if the identifier for the target file name does not match file name identifier for any of the data name directory entries.
16. The method as recited in claim 15 further comprising:
- determining that the identifier for the target file name matches at least one file name identifier in the data name directory entries;
- obtaining a full file name of one or more matching data name directory entries;
- comparing the target file name with the full file of the matching data name directory entries; and
- generating a new data name directory entry for the target file name if the identifier for the target file name does not match file name identifier for any of the data name directory entries.
17. The method as recited in claim 16 further comprising rejecting the target file name for data if the target file name matches the full file name of the matching data name directory entries.
18. The method as recited in claim 16 further comprising identifying the target file name as matching an existing directory entry if the target file name matches the full file name of each directory entries.
19. The method as recited in claim 15, wherein generating a new data name directory entry for the target file name if the identifier for the target file name does not match file name identifier for any of the data name directory entries includes generating a primary directory entry including the target file name and the identifier of the target file name.
20. The method as recited in claim 15, wherein obtaining a target file name includes obtaining a file creation request.
Type: Application
Filed: Mar 20, 2008
Publication Date: Sep 4, 2008
Applicant: MICROSOFT CORPORATION (Redmond, WA)
Inventors: Ravisankar V. Pudipeddi (Bellevue, WA), Vishal V. Ghotge (Seattle, WA)
Application Number: 12/052,603
International Classification: G06F 17/30 (20060101);