Identifying the owner responsible for processing I/O requests

• US 6,349,313 B1
• Filed: 08/31/2000
• Issued: 02/19/2002
• Est. Priority Date: 09/19/1997
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Kimura, Gary D., Cabrera, Luis Felipe, Momoh, Oshoma
• Primary Examiner(s): Von Buhr, Maria N.
• Application Number:
  US09/652,347
• Time in Patent Office: 537 Days
• Field of Search: 707/1, 707/3, 707/10, 707/100-104, 707/200, 707/205
• US Class Current: 1/1
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99956 File allocation

Abstract

A processing system processes an I/O request and, upon interruption of the I/O request, identifies an owner of an active mount point or another entity, and then resumes processing the I/O request under the control of the identified owner. For instance, when an I/O request processed by an I/O system encounters an active mount point, the processing is interrupted as control is turned over to an active mount point driver. The active mount point driver assumes responsibility for processing the I/O request. In processing the I/O request, the active mount point driver decides what action should be taken to further processing of the I/O request. To further processing of the I/O request, the active mount point driver may utilize information from a variety of sources as well as make requests to other processes, drivers, systems, subsystems, devices, and so forth. Such actions may include those normally associated with an I/O request such as retrieving and mounting appropriate media as well as actions not normally associated with an I/O request. This technique allows arbitrary actions to be performed when grafting the name space of one device into the name space of the same or another device using active mount points.

Claims

1. In a processing system that processes I/O requests with respect to an entity associated with the processing system, a method for interrupting a sequence of processing an I/O request with respect to the entity and identifying an owner of the entity that is responsible for continuing processing of the I/O request, comprising:

while processing an I/O request associated with the entity using a driver included in the processing system, encountering the entity and interrupting the processing of the I/O request in response to an attribute of the entity that specifies that the interruption is to be executed;

upon execution of the interruption, identifying an owner of the entity that is responsible for continuing processing of the I/O request after the interruption, the owner being identified by the attribute of the entity;

transferring control to the identified owner; and

after the interruption, said identified owner continuing processing of the I/O request.

2. A method as recited in claim 1, wherein the entity is an active mount point in the name space of a first device associated with the processing system, the active mount point grafting a name space of a second device into the name space of the first device.

3. A method as recited in claim 1, wherein the entity is an active mount point in the name space of a first device associated with the processing system, the active mount point grafting a portion of the name space of the first device into another location in the name space of the same device.

4. A method as recited in claim 1, wherein the attribute comprises a tag field stored in a first region of a range of storage locations in said processing system, said tag field comprising information representing said owner of said entity.

5. A method as recited in claim 1, wherein the attribute comprises a tag field stored in a first region of a range of storage locations in said processing system, said tag field comprising a tag value region containing information that identifies said owner when said entity is encountered when processing said I/O request.

6. A method as recited in claim 1, wherein said attribute comprises a value field containing data stored therein by said owner, said value field being stored in a second region of said range of storage locations of said processing system.

7. A method as recited in claim 1, wherein the attribute comprises a tag field stored in a first region of a range of storage locations in said processing system, the said tag field comprising a flag region for storing flags indicating discrete characteristics of said entity.

8. A method as recited in claim 1, wherein said entity is one of a directory on a disk and a file and wherein said attribute comprises a data field stored in a third region of a range of storage locations of said processing system, said data field storing data comprising the standard MS-DOS attribute information.

9. A method as recited in claim 1, wherein said entity is one of a directory on a disk and a file and wherein said attribute further comprises a data field stored in a third region of a range of storage locations of said processing system, said data field storing security information that specifies rights that individuals or groups have with respect to said entity.

10. A method as recited in claim 1, wherein said entity is a directory on a disk and wherein said attribute further comprises a data field stored in a third region of a range of storage locations of said processing system, said data field storing information that allows a file system of said processing system to locate files and other directories stored in said directory on said disk.

11. A method as recited in claim 1, wherein said entity is a file and wherein said attribute further comprises a data field stored in a third region of a range of storage locations of said processing system, said data field storing user information in said file.

12. In a processing system that includes a computer-readable medium having stored thereon a plurality of data fields, said data fields associated with an attribute of an entity accessible by the file system of a computer, a method for interrupting a sequence of processing an I/O request with respect to the entity and identifying an owner of the entity that is responsible for continuing processing of the I/O request comprising:

accessing a first data field stored in a first region of a range of storage locations in said medium, said first data field comprising a first data representing the name of said entity;

accessing a second data field stored in a second region of said range of storage locations, said second data field storing second data that causes an interruption of the normal sequence of processing an I/O request when said entity is encountered when processing said I/O request, said second data including;

a tag value region for storing information that identifies an owner of said entity, said owner being responsible for processing said I/O request after said interruption; and

a value region for storing information placed there by said owner;

while processing an I/O request associated with the entity using a driver included in the processing system, encountering said entity and interrupting the processing of the I/O request in response to said second data field;

upon execution of the interruption, identifying an owner of the entity, the owner being identified by information in said tag value region;

transferring control to the identified owners and after the interruption, said identified owner continuing processing of the I/O request.

13. A method as recited in claim 12, wherein the entity is an active mount point in the name space of a first device associated with the processing system, the active mount point grafting a name space of a second device into the name space of the first device.

14. A method as recited in claim 12, wherein the tag region comprises a flag region for storing flags indicating discrete characteristics of said entity and a tag value region that stores said information that identifies said owner.

15. A method as recited in claim 12, wherein said entity is one of a directory on a disk and a file and wherein said set of data fields further comprises a third data field stored in a third region of said range of storage locations, said third data field storing data comprising the standard MS-DOS attribute information.

16. A method as recited in claim 12, wherein said entity is one of a directory on a disk and a file and wherein said set of data fields further comprises a fourth data field stored in a fourth region of said range of storage locations, said fourth data field storing security information that specifies the rights that individuals or groups have with respect to said entity.

17. A method as recited in claim 16, wherein said entity is said directory on said disk and wherein said set of data fields further comprises a fifth data field stored in a fifth region of said range of storage locations, said fifth data field storing information that allows the file system of said computer to locate files and other directories stored in said directory on said disk.

18. A method as recited in claim 16, wherein said entity is said file and wherein said set of data fields further comprises a fifth data field stored in a fifth region of said range of storage locations, said fifth data field storing user information in said file.

19. In a processing system that includes a computer-readable medium having stored thereon a plurality of data fields, said data fields associated with an attribute of an entity accessible by the file system of a computer, a method for interrupting a sequence of processing an I/O request with respect to the entity and identifying an owner of the entity that is responsible for continuing processing of the I/O request, comprising:

accessing a tag field containing data representing an owner of said entity, said tag field being stored in a first region of a range of storage locations in said medium, said tag field comprising;

a flag region comprising at least one flag, said at least one flag indicating at least one discrete characteristic including at least one of a latency flag indicating a high retrieval time and a surrogate flag indicating a name surrogate; and

a tag value region for storing information that identifies an owner of said entity, said owner being responsible for processing said I/O request after said interruption; and

accessing a value field containing data stored therein by said owner, said value field being stored in a second region of said range of storage locations;

while processing an I/O request associated with the entity using a driver included in the processing system, encountering the entity and interrupting the processing of the I/O request in response to said tag field;

upon execution of the interruption, identifying an owner of the entity, the owner being identified by information in said tag value region;

transferring control to the identified owner; and

after the interruption, said identified owner continuing processing of the I/O request.

20. A method as recited in claim 19, wherein the entity is an active mount point and said identified owner is one of a plurality of drivers associated with the computer, wherein each of the plurality of drivers:

can be identified as an owner of a particular active mount point; and

when identified as said owner of said particular active mount point, can perform an action to firther completion of a particular I/O request associated with said particular active mount point.