Efficient Stacked File System And Method

• US 20090030935A1
• Filed: 07/17/2008
• Published: 01/29/2009
• Est. Priority Date: 07/26/2007
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Kurichiyath, Sudheer, Murthy, Arun Keshava
• Granted Patent: US 8,032,570 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/17 Details of further file system functions

Abstract

An efficient stacked file system and method are disclosed herein. The stacked file system is capable of inserting a layer into a stack and ejecting the same from the stack in accordance with the requirement of the functionalities provided by the layer; thereby minimises adverse affect on the overall file system performance.

Claims

1. A stacked file system comprising:

a stack having at least a file system stacked on top of an underlying file system; and

a stack manager having a logic for managing the stack.

2. The system of claim 1, wherein the logic comprises an eject operation for ejecting a file system from the stack.

3. The system of claim 2, wherein the eject operation comprises executing an algorithm comprising:

obtaining a mount point of the file system; and

ejecting the file system at the identified mount point by passing information handled by the file system being ejected to the underlying file system.

4. The system of claim 1, wherein the logic comprises an insert operation for inserting a file system into the stack.

5. The system of claim 4, wherein insert operation comprises executing an algorithm comprising:

determining a mount point for the file system; and

inserting the file system at the identified mount point by retrieving information handled by the file system below the inserting file system and updating the retrieved information with information associating with the inserting file system for handling thereby.

6. A method for managing a stack, the stack having at least a file system stacked on top of an underlying file system, the method comprising ejecting a first file system from the stack.

7. The method of claim 6, wherein ejecting the first file system comprises

obtaining a mount point of the first file system;

and

ejecting the first file system at the identified mounting point.

8. The method of claim 7, wherein ejecting the first file system comprises transferring vnodes associating with the first file system to the underlying file system.

9. The method of claim 6 further comprising inserting a second file system into the stack.

10. The method of claim 9, wherein inserting the second file system comprises:

determining a mount point for the second file system; and

inserting the second file system at the identified mounting point.

11. The method of claim 10, wherein inserting the second file system comprises:

freezing operations of the stack;

retrieving information on the stack;

updating the retrieved information with information of the second file system; and

unfreezing the operations of the stack.

12. The method of claim 11, wherein retrieving information on the stack comprises retrieving vnodes of the stack.

13. The method of claim 12, wherein updating the retrieved information comprises creating new vnodes incorporating information from the second file system.

14. The method of claim 13 further comprising updating directory cache with tuple of the second file system.

16. A computer readable medium having a software program stored thereon, the software program comprising instructions for performing the method of claim 6.

15. A computer system comprising a memory including a stack that has at least a file systems stacked on top of an underlying file system and a stack manager capable of inserting a file system into the stack and ejecting the file system from the stack.