Method, apparatus and computer program product for file system referrals

• US 20030204530A1
• Filed: 04/24/2002
• Published: 10/30/2003
• Est. Priority Date: 04/24/2002
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Everhart, Craig Fulmer, Shmueli, Boaz, Anderson, Owen Theodore
• Granted Patent: US 6,836,775 B2
• Time in Patent Office: Days
• US Class Current: 707/200
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

In one form, in a method for making file systems accessible, a referring file system attribute is created, responsive to a first file system having a referral object referring to a second file system. The referring file system attribute describes referring file system identification for the first file system. A path attribute is created, responsive to the first file system having the referral object, describing a path from a root of the first file system to the referral object. A referred file system attribute is created, responsive to the first file system having the referral object, describing a referred file system identification for the second file system. A parent attribute is created, responsive to the first file system having the referral object, describing a parent flag for the second file system.

Claims

1. A method for making a number of file systems accessible, the method comprising:

creating a referring file system attribute of a data element, responsive to a first one of the file systems having a first referral object referring to a second one of the file systems, the referring file system attribute describing a first referring file system identification for the first one of the file systems;

creating a path attribute of the data element, responsive to the first one of the file systems having the first referral object, the path attribute describing a first path information for the first referral object, wherein the first one of the file systems has a root and the first path information is for a path from the first one of the file systems root to the first referral object;

creating a referred file system attribute of the data element, responsive to the first file system having the first referral object, the first referred file system attribute describing a first referred file system identification for the second one of the file systems; and

creating a parent attribute of the data element, responsive to the first file system having the first referral object, the parent attribute describing a first parent flag for the second one of the file systems.

2. The method of claim 1, wherein the file systems are accessible within a global name space.

3. The method of claim 2, comprising:

configuring data elements for respective referral objects within the global name space; and

storing the data elements in a database.

4. The method of claim 3, comprising storing a dummy data element in the database, the dummy data element describing a dummy referral to a root file system of the global name space.

5. The method of claim 4, comprising:

receiving a request to locate a parent directory of a second referral object, the second referral object being located in a second referred file system;

searching the database for an entry matching the second referred file system; and

selecting the entry matching the second referred file system, wherein the entry has the parent attribute set to a true status.

6. The method of claim 4, comprising browsing the global name space at a file system level by accessing the database.

7. The method of claim 1, comprising generating a second data element in response to creation of a second referral object, the second data element describing a second referring file system identifier, a second path information, a second referred file system identifier and a second principal parent flag indicating whether the second referring file system is the principal parent of the second referred file system.

8. The method of claim 7, comprising deleting the second data element in response to deletion of the second referral object

9. The method of claim 7, wherein the creation of the second referral object comprises:

determining whether the second referral object is a first referral to the referred file system; and

setting the first parent flag for the new referral object to a true status responsive to determining that the second referral object is the first referral.

10. The method of claim 9, comprising setting the first parent flag for the second referral object to a false status responsive to determining that the second referral object is not the first referral.

11. An apparatus comprising:

a processor;

a file system coupled to a number of file systems;

a memory storing instructions operable with the processor for accessing the number of file systems, the instructions being executed for;

creating a referring file system attribute of a data element, responsive to a first one of the file systems having a first referral object referring to a second one of the file systems, the referring file system attribute describing a first referring file system identification for the first one of the file systems;

creating a path attribute of the data element, responsive to the first one of the file systems having the first referral object, the path attribute describing a first path information for the first referral object, wherein the first one of the file systems has a root and the first path information is for a path from the first one of the file systems root to the first referral object;

creating a referred file system attribute of the data element, responsive to the first file system having the first referral object, the first referred file system attribute describing a first referred file system identification for the second one of the file systems; and

creating a parent attribute of the data element, responsive to the first file system having the first referral object, the parent attribute describing a first parent flag for the second one of the file systems.

12. The apparatus of claim 11, wherein the file systems are accessible within a global name space.

13. The apparatus of claim 12, the instructions being executed for:

configuring data elements for respective referral objects within the global name space; and

storing the data elements in a database.

14. The apparatus of claim 13, the instructions being executed for storing a dummy data element in the database, the dummy data element describing a dummy referral to a root file system of the global name space.

15. The apparatus of claim 14, the instructions being executed for:

receiving a request to locate a parent directory of a second referral object, the second referral object being located in a second referred file system;

searching the database for an entry matching the second referred file system; and

selecting the entry matching the second referred file system, wherein the entry has the parent attribute set to a true status.

16. The apparatus of claim 14, the instructions being executed for browsing the global name space at a file system level by accessing the database.

17. The apparatus of claim 11, the instructions being executed for generating a second data element in response to creation of a second referral object, the second data element describing a second referring file system identifier, a second path information, a second referred file system identifier and a second principal parent flag indicating whether the second referring file system is the principal parent of the second referred file system.

18. The apparatus of claim 17, the instructions being executed for deleting the second data element in response to deletion of the second referral object

19. The apparatus of claim 17, wherein the creation of the second referral object comprises:

determining whether the second referral object is a first referral to the referred file system; and

setting the first parent flag for the new referral object to a true status responsive to determining that the second referral object is the first referral.

20. The apparatus of claim 19, the instructions being executed for setting the first parent flag for the second referral object to a false status responsive to determining that the second referral object is not the first referral.

21. A computer program product for use in making a number of file systems accessible, the computer program product comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform:

creating a referring file system attribute of a data element, responsive to a first one of the file systems having a first referral object referring to a second one of the file systems, the referring file system attribute describing a first referring file system identification for the first one of the file systems;

creating a path attribute of the data element, responsive to the first one of the file systems having the first referral object, the path attribute describing a first path information for the first referral object, wherein the first one of the file systems has a root and the first path information is for a path from the first one of the file systems root to the first referral object;

creating a referred file system attribute of the data element, responsive to the first file system having the first referral object, the first referred file system attribute describing a first referred file system identification for the second one of the file systems; and

creating a parent attribute of the data element, responsive to the first file system having the first referral object, the parent attribute describing a first parent flag for the second one of the file systems.

22. The computer program product of claim 21, wherein the file systems are accessible within a global name space.

23. The computer program product of claim 22, wherein the computer readable storage media causes the control circuitry to perform:

configuring data elements for respective referral objects within the global name space; and

storing the data elements in a database.

24. The computer program product of claim 23, wherein the computer readable storage media causes the control circuitry to perform:

storing a dummy data element in the database, the dummy data element describing a dummy referral to a root file system of the global name space.

25. The computer program product of claim 24, wherein the computer readable storage media causes the control circuitry to perform:

receiving a request to locate a parent directory of a second referral object, the second referral object being located in a second referred file system;

searching the database for an entry matching the second referred file system; and

selecting the entry matching the second referred file system, wherein the entry has the parent attribute set to a true status.

26. The computer program product of claim 24, wherein the computer readable storage media causes the control circuitry to perform:

browsing the global name space at a file system level by accessing the database.

27. The computer program product of claim 21, wherein the computer readable storage media causes the control circuitry to perform:

generating a second data element in response to creation of a second referral object, the second data element describing a second referring file system identifier, a second path information, a second referred file system identifier and a second principal parent flag indicating whether the second referring file system is the principal parent of the second referred file system.

28. The computer program product of claim 27, wherein the computer readable storage media causes the control circuitry to perform:

deleting the second data element in response to deletion of the second referral object

29. The computer program product of claim 27, wherein the creation of the second referral object comprises:

determining whether the second referral object is a first referral to the referred file system; and

setting the first parent flag for the new referral object to a true status responsive to determining that the second referral object is the first referral.

30. The computer program product of claim 29, wherein the computer readable storage media including causes the control circuitry to perform:

setting the first parent flag for the second referral object to a false status responsive to determining that the second referral object is not the first referral.

31. An apparatus for making a number of file systems accessible, the apparatus comprising:

means for creating a referring file system attribute of a data element, responsive to a first one of the file systems having a first referral object referring to a second one of the file systems, the referring file system attribute describing a first referring file system identification for the first one of the file systems;

means for creating a path attribute of the data element, responsive to the first one of the file systems having the first referral object, the path attribute describing a first path information for the first referral object, wherein the first one of the file systems has a root and the first path information is for a path from the first one of the file systems root to the first referral object;

means for creating a referred file system attribute of the data element, responsive to the first file system having the first referral object, the first referred file system attribute describing a first referred file system identification for the second one of the file systems; and

means for creating a parent attribute of the data element, responsive to the first file system having the first referral object, the parent attribute describing a first parent flag for the second one of the file systems.

32. The apparatus of claim 31, wherein the file systems are accessible within a global name space.

33. The apparatus of claim 32, comprising:

means for configuring data elements for respective referral objects within the global name space; and

means for configuring the data elements in a database.

34. The apparatus of claim 33, comprising:

means for storing a dummy data element in the database, the dummy data element describing a dummy referral to a root file system of the global name space.

35. The apparatus of claim 34, comprising:

means for receiving a request to locate a parent directory of a second referral object, the second referral object being located in a second referred file system;

means for searching the database for an entry matching the second referred file system; and

means for selecting the entry matching the second referred file system, wherein the entry has the parent attribute set to a true status.

36. The apparatus of claim 34, comprising:

means for browsing the global name space at a file system level by accessing the database.

37. The apparatus of claim 31, comprising:

means for generating a second data element in response to creation of a second referral object, the second data element describing a second referring file system identifier, a second path information, a second referred file system identifier and a second principal parent flag indicating whether the second referring file system is the principal parent of the second referred file system.

38. The apparatus of claim 37, comprising:

means for deleting the second data element in response to deletion of the second referral object

39. The apparatus of claim 37, comprising:

means for determining whether the second referral object is a first referral to the referred file system; and

means for setting the first parent flag for the new referral object to a true status responsive to determining that the second referral object is the first referral.

40. The apparatus of claim 39, comprising:

means for setting the first parent flag for the second referral object to a false status responsive to determining that the second referral object is not the first referral.