Data access management

Patent metadata

Field	Value
Publication number	US-9032163-B2
Application number	US-88801710-A
Country	US
Kind code	B2
Filing date	Sep 22, 2010
Priority date	Sep 22, 2010
Publication date	May 12, 2015
Grant date	May 12, 2015

Abstract

Apparatus, systems, and methods may operate to assert a first semi-exclusive write lock with respect to a storage medium area by storing lock information when assertion of another semi-exclusive write lock with respect to the area is not detected. Additional activities may include writing data to the area by a writing entity that has asserted the first semi-exclusive write lock after determining the lock information has not changed, while substantially simultaneously de-asserting the first semi-exclusive write lock. Reading from the area may be determined as successful by determining that the semi-exclusive write lock was not asserted prior to or during the reading by checking the status of the lock information. Additional apparatus, systems, and methods are disclosed.

First claim

What is claimed is:

1. An apparatus, comprising:
a reserved area of a block of a storage medium housed by a first physical node; and an access supervision processor:
to receive a write request to write to a block including a reserved area;
to assert a first semi-exclusive write lock by storing new lock information in the reserved area in response to determining that current lock information of the reserved area, retrieved by a first read of the block in response to the write request, does not indicate assertion of a second semi-exclusive write lock corresponding to another write request;
to determine that the new lock information in the reserved area has not changed via a second read of the block following the assertion of the first semi-exclusive write lock; and
to write, in response to the determination that the new lock information is unchanged, to the block both data and reset information at the same time, the reset information being written to the reserved area and indicating de-assertion of the first semi-exclusive write lock.

2. The apparatus of claim 1 , further comprising:
a second node to house the access supervision processor.

3. The apparatus of claim 1 , further comprising:
a display to display at least a portion of the data.

4. The apparatus of claim 1 , further comprising:
multiple processors, including the access supervision processor.

5. The apparatus of claim 1 , wherein the reserve area comprises non-volatile memory.

6. A processor-implemented method to execute on one or more processors that perform the method, comprising:
receiving a write request to write to a block including a reserved area;
asserting a first semi-exclusive write lock with respect to reserved area of a block of a storage medium by storing new lock information in the reserved area in response to determining that current lock information of the reserved area, retrieved by a first read of the block in response to the write request, does not indicate assertion of a second semi-exclusive write lock corresponding to another write request;
determining that the new lock information in the reserved area has not changed via a second read of the block following the assertion of the first semi-exclusive write lock; and
writing, in response to the determination that the new lock information is unchanged, to the block both data and reset information at the same time, the reset information being written to the reserved area and indicating de-assertion of the first semi-exclusive write lock.

7. The method of claim 6 , wherein the reset information comprises a series of bits having the same single value.

8. The method of claim 6 , wherein the new lock information comprises a writing entity identifier and/or a timestamp.

9. The method of claim 6 , further comprising:
detecting assertion of the second semi-exclusive write lock with respect to the reserved area; and
refraining from the asserting until the assertion of the second semi-exclusive write lock is no longer detected.

10. The method of claim 6 , wherein the determining further comprises:
determining, by the writing entity, that the new lock information has changed to include a valid writing entity identifier that is not associated with the writing entity, and a valid timestamp; and
waiting, for a selected write timeout period after a time associated with the timestamp, prior to repeating the asserting by the writing entity.

11. The method of claim 6 , wherein the determining further comprises:
determining, by the writing entity, that the new lock information has changed to include an invalid writing entity identifier or an invalid timestamp; and
repeating the asserting by the writing entity without waiting for a selected write timeout period after a time associated with the timestamp.

12. A non-transitory machine readable medium including instructions that, when executed by a processor, cause the processor to perform operations comprising:
receiving a write request to write to a block including a reserved area;
asserting a first semi-exclusive write lock with respect to reserved area of a block of a storage medium by storing new lock information in the reserved area in response to determining that current lock information of the reserved area, retrieved by a first read of the block in response to the write request, does not indicate assertion of a second semi-exclusive write lock corresponding to another write request;
determining that the new lock information in the reserved area has not changed via a second read of the block following the assertion of the first semi-exclusive write lock; and
to write, in response to the determination that the new lock information is unchanged, to the block both data and reset information at the same time, the reset information being written to the reserved area and indicating de-assertion of the first semi-exclusive write lock.

13. The machine readable medium of claim 12 , wherein the reset information comprises a series of bits having the same single value.

14. The machine readable medium of claim 12 , wherein the new lock information comprises a writing entity identifier and/or timestamp.

15. The machine readable medium of claim 12 , further comprising:
detecting assertion of the second semi-exclusive write lock with respect to the reserved area; and
refraining from the asserting until the assertion of the second semi-exclusive write lock is no longer detected.

16. The machine readable medium of claim 12 , wherein the determining further comprises:
determining, by the writing entity, that the new lock information has changed to include a valid writing entity identifier that is not associated with the writing entity, and a valid timestamp; and
waiting, for a selected write timeout period after a time associated with the timestamp, prior to repeating the asserting by the writing entity.

17. The machine readable medium of claim 12 , wherein the determining further comprises:
determining, by the writing entity, that the new lock information has changed to include an invalid writing entity identifier or an invalid timestamp; and
repeating the asserting by the writing entity without waiting for a selected write timeout period after a time associated with the timestamp.

Assignees

• Sudhakar Gosukonda Naga Venkata Satya
• Novell Inc

Inventors

• Sudhakar Gosukonda Naga Venkata Satya

Classifications

• G06F9/526 Primary

  Mutual exclusion algorithms · CPC title