Method of and system for reverse mapping vnode pointers

• US 8,615,502 B2
• Filed: 04/20/2009
• Issued: 12/24/2013
• Est. Priority Date: 04/18/2008
• Status: Active Grant

• Current Assignee: McAfee, LLC
• Original Assignee: McAfee, Inc. (McAfee, LLC)
• Inventors: Saraf, Suman, Agrawal, Sharad, Srivastava, Vivek
• Primary Examiner(s): Hoang, Son T
• Application Number:
  US12/426,859
• Publication Number:
  US 20130246393A1
• Time in Patent Office: 1,709 Days
• Field of Search: 707/822, 707/694, 707/802
• US Class Current: 707/694
• CPC Class Codes: G06F 16/196 Specific adaptations of the file system to access devices and non-file objects via standard file system access operations, e.g. pseudo file systems dedicated interfaces to storage systems G06F3/0601
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

Embodiment of the invention provide a reverse name lookup function for providing an absolute path name or file name and absolute path name to the file name parent directory based on a vnode reference, NFS file handle reference, or file identifier reference associated with a computer virtual file system. A method in accordance with the invention comprises populating a table structure with vnodes, names, and absolute path information associated with the vnodes. The table structure and information are sufficient to generate an absolute path name and file name for each vnode. The table structure also includes entries for file identifiers, names, and associated absolute path information associated with the file identifiers. This information is sufficient to generate an absolute path name for each file identifier. The table is populated by hooking virtual file system function calls including the vnode name lookup function and the vnode inactive function. The table is populated with the file identifier entries by hooking the vnode inactive function.

Claims

1. Logic encoded in a non-transitory computer-readable storage medium and, when executed by a computer processor, is operable to perform operations of reverse mapping virtual node (vnode) pointers, comprising:

using a reverse name lookup cache (RNLC) to translate vnode pointers and file identifiers into file names and absolute path names, the operations comprising;

intercepting a first function call into a virtual file system layer, wherein the first function call includes a first name of a file and first path name information associated with a first file reference of the file, and wherein the first intercepted function call is processed in the virtual file system layer to return the first file reference;

populating a first entry of a table structure with the first file reference, the first name, and the first path name information, wherein the table holds one or more file references, names, and path name information, wherein

one or more entries in the table structure have sufficient information to determine an absolute path name to the file,

the table structure is organized into a vnode pointer (vp) table and a file identifier (fid) table, wherein each vp entry in the vp table comprises a vnode reference and absolute path information associated with a corresponding vnode, and

each fid entry in the fid table comprises a file structure and absolute path information associated with a corresponding fid; and

converting a particular vnode reference to a particular file identifier upon trapping a function call inactivating a corresponding vnode, wherein the table structure is further populated with a particular file name associated with the corresponding inactivated vnode.

2. The logic of claim 1, wherein the one or more file references in the table structure are vnode references, Network File System (NFS) file handles, file identifier references, or a combination thereof.

3. The logic of claim 2, further comprising:

the determining the absolute path name to the file from at least one of the vnode references or at least one of the file identifier references in the table structure.

4. The logic of claim 1, wherein the processor is operable to perform further operations comprising:

intercepting a second function call into the virtual file system layer, wherein the second function call is intercepted before the first function call, wherein the second function call includes a second name of a directory of the file and second path name information associated with a second file reference of the directory, and wherein the second intercepted function call is processed in the virtual file system layer to return the second file reference; and

populating a second entry of the table structure with the second file reference, the second name, and the second path name information.

5. A method for reverse mapping virtual node (vnode) pointers comprising:

using a reverse name lookup cache (RNLC) to translate vnode pointers and file identifiers into file names and absolute path names, the operations comprising;

intercepting a first function call into a virtual file system layer, wherein the first function call includes a first name of a file and first path name information associated with a first file reference of the file, and wherein the first intercepted function call is processed in the virtual file system layer to return the first file reference;

populating a first entry of a table structure with the first file reference, the first name, and the first path name information, wherein the table holds one or more file references, names, and path name information, wherein

one or more entries in the table structure have sufficient information to determine an absolute path name to the file,

the table structure is organized into a vnode pointer (vp) table and a file identifier (fid) table, wherein each vp entry in the vp table comprises a vnode reference and absolute path information associated with a corresponding vnode, and

each fid entry in the fid table comprises a file structure and absolute path information associated with a corresponding fid; and

converting a particular vnode reference to a particular file identifier upon trapping a function call inactivating a corresponding vnode, wherein the table structure is further populated with a particular file name associated with the corresponding inactivated vnode.

6. The method of claim 5, wherein the one or more file references in the table structure are vnode references, Network File System (NFS) file handles, file identifier references, or a combination thereof.

7. The method of claim 5, further comprising:

determining the absolute path name to the file from at least one of the vnode references or at least one of the file identifier references in the table structure.

8. The method of claim 5, further comprising:

intercepting a second function call into the virtual file system layer, wherein the second function call is intercepted before the first function call, wherein the second function call includes a second name of a directory of the file and second path name information associated with a second file reference of the directory, and wherein the second intercepted function call is processed in the virtual file system layer to return the second file reference; and

populating a second entry of the table structure with the second file reference, the second name, and the second path name information.

9. The method of claim 8, wherein the absolute path name to the file is determined from the first name and an absolute path name to the directory.

10. The method of claim 5, wherein the first path name information includes one of the absolute path name to the file or a linkage to one or more other entries in the table structure containing at least part of the absolute path name to the file.

11. The method of claim 5, wherein the first function call is a vnode lookup operation with a first name parameter representing the file, wherein the vnode lookup operation returns a vnode pointer for the file, and wherein the first file reference stored in the first entry is a vnode reference representing the vnode pointer for the file.

12. The method of claim 5, wherein the first function call is a vnode release operation with a first vnode parameter, wherein a file identifier corresponding to the first vnode parameter is determined, and wherein the first file reference stored in the first entry of the table structure is a file identifier reference representing the corresponding file identifier.

13. A computer device for reverse mapping virtual node (vnode) pointers comprising:

a table structure configured to store one or more entries, each entry including a file reference, a name, and path information;

a program module for populating the table structure; and

one or more computer processors operable to execute operations associated with the table structure and the program module using a reverse name lookup cache (RNLC) to translate the vnode pointers and file identifiers into file names and absolute path names, the operations comprising;

intercepting a first function call into a virtual file system layer, wherein the first function call includes a first name of a file and first path name information associated with a first file reference of the file, and wherein the first intercepted function call is processed in the virtual file system layer to return the first file reference; and

populating a first entry of the table structure with the first file reference, the first name, and the first path name information, wherein

one or more entries in the table structure have sufficient information to determine an absolute path name to the file,

the table structure is organized into a vnode pointer (vp) table and a file identifier (fid) table, wherein each vp entry in the vp table comprises a vnode reference and absolute path information associated with a corresponding vnode, and

each fid entry in the fid table comprises a file structure and absolute path information associated with a corresponding fid; and

converting a particular vnode reference to a particular file identifier upon trapping a function call inactivating a corresponding vnode, wherein the table structure is further populated with a particular file name associated with a the corresponding inactivated vnode.

14. The computer device of claim 13, wherein the first file reference is a vnode reference, a Network File System (NFS) file handle, or a file identifier reference.

15. The computer device of claim 14, wherein the one or more processors are operable to perform further operations comprising:

the determining the absolute path name to the file in response to receiving a vnode reference or a file identifier reference.

16. The computer device of claim 13, wherein the one or more processors are operable to perform further operations comprising:

intercepting a second function call into the virtual file system layer, wherein the second function call is intercepted before the first function call, wherein the second function call includes a second name of a directory of the file and second path name information associated with a second file reference of the directory, and wherein the second intercepted function call is processed in the virtual file system layer to return the second file reference; and

populating a second entry of the table structure with the second file reference, the second name, and the second path name information.

17. The computer device of claim 16, wherein the absolute path name to the file is determined from the first name and an absolute path name to the directory.