CIFS access to NFS files and directories by translating NFS file handles into pseudo-pathnames

• US 9,110,920 B1
• Filed: 05/03/2007
• Issued: 08/18/2015
• Est. Priority Date: 05/03/2007
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Amegadzie, Augustine, Caccavale, Frank S., Jiang, Xiaoye, Wei, Ka-Lai
• Primary Examiner(s): Bengzon, Greg C
• Application Number:
  US11/744,200
• Time in Patent Office: 3,029 Days
• Field of Search: 709212-213, 709217-219, 709/203, 709/239, 709/249, 709/200, 707/821, 707/827, 707/831, 707/899, 711/202, 711/206, 711/217
• US Class Current: 1/1
• CPC Class Codes: G06F 16/13 File access structures, e.g. distributed indices arrangements of input from, or output to, record carriers G06F3/06
• CPC Class Codes: G06F 16/183 Provision of network file services by network file servers, e.g. by using NFS, CIFS network file access protocols H04L67/1097
• 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

Abstract

A file handle produced by a file server is encoded into a pseudo-pathname used as a substitute for a pathname in a network file access protocol for accessing a file in the file server. The method avoids repeating a directory lookup and may permit the network file access protocol to access a file that has been renamed since the file handle was produced. The method is particularly advantageous for enabling a file server to use a CIFS client for virus checking or backup of a file modified by an NFS client. In a preferred implementation, the encoding of the file handle into a pseudo-pathname involves converting the file handle to an ASCII hexadecimal format to produce a component name, and appending the component name to a special name of a pseudo-directory of file handles of files in a file system.

Claims

1. A method of accessing a file in a file server, the file server storing a file system including the file and a directory including a name of the file, the file having a pathname including the name of the directory and the name of the file in the directory, said method comprising:

(a) the file server producing a file handle for locating the file in the file server;

(b) encoding the file handle in a pseudo-pathname; and

(c) a client using the pseudo-pathname as a substitute for the pathname of the file in a network file access protocol for accessing the file in the file server; and

(d) the file server recognizing that the pseudo-pathname has been used as a substitute for the pathname of the file in the file access protocol, and upon recognizing that the pseudo-pathname has been used as a substitute for the pathname of the file in the file access protocol, the file server decoding the file handle from the pseudo-pathname and using the file handle for locating and accessing the file in the file server without searching any directory of the file system.

2. The method as claimed in claim 1, wherein the file server produces the file handle when accessing the file in accordance with the Network File System (NFS) protocol, and the client uses the pseudo-pathname as a substitute for the pathname of the file in the Common Internet File Access (CIFS) protocol.

3. The method as claimed in claim 1, wherein the pseudo-pathname includes a special name indicating that the file handle is encoded into the pseudo-pathname, and the file server decodes the file handle from the pseudo-pathname upon recognizing the special name in the file handle.

4. The method as claimed in claim 3, wherein the pseudo-pathname includes an alphanumeric string immediately following the special name, and the file handle is encoded into the alphanumeric string.

5. The method as claimed in claim 4, wherein the alphanumeric string is a hexadecimal representation of the numeric value of the file handle.

6. The method as claimed in claim 3, wherein the special name is the name of a pseudo-directory of the file system, the pseudo-directory is not contained in storage of the file server, yet an operating system of the file server successfully executes a command to set a current directory for command interpretation to the pseudo-directory so that file handles are decoded from pathnames in subsequent operating system commands.

7. The method as claimed in claim 1, wherein the file server returns the file handle in response to a client request to lookup the file in the directory given the name of the file in the directory.

8. The method as claimed in claim 1, wherein the client uses the pseudo-pathname as a substitute for the pathname of the file in the network file access protocol by including the pseudo-pathname in a request to open the file, and the file server opens the file for the client and returns a file identifier to the client in an acknowledgement that the file has been opened for the client, and the client uses the network file access protocol to read the data from the file by using the file identifier in a request to the file server for reading the data from the file.

9. The method as claimed in claim 1, which includes the file server responding to termination of access to the file by encoding the file handle to produce the pseudo-pathname, and sending a service request including the pseudo-pathname to the client.

10. The method as claimed in claim 1, which includes the file server responding to modification of data of the file by encoding the file handle to produce the pseudo-pathname, and sending a virus scan request including the pseudo-pathname to the client.

11. The method as claimed in claim 1, which includes the file server responding to modification of data of the file by encoding the file handle to produce the pseudo-pathname, and sending a file backup request including the pseudo-pathname to the client.

12. A method of sharing access to a file of a file system between a first client and a second client, the file system being stored in a file server providing service to the first client and the second client, said method comprising:

(a) the first client using the Network File Access (NFS) protocol to send to the file server a directory lookup request to locate a file specified by a name of the file, and the file server responding by locating the file and returning an NFS file handle to the first client, and the first client using the NFS protocol to send to the file server a write request including the NFS file handle to write data to the file, and the file server responding by writing the data to the file; and

(b) the second client using the Common Internet File System (CIFS) protocol to send to the file server a request to open the file, the request to open the file including a pseudo-pathname specifying the file, the pseudo-pathname being used as a substitute for a pathname of the file in the CIFS protocol, and the file server decoding the NFS file handle from the pseudo-pathname and using the NFS file handle for locating and opening the file, and the file server returning to the second client a File ID, and the second client using the CIFS protocol to send to the file server a read request including the File ID to read the data from the file, and the file server responding by reading the data from the file and returning the data read from the file to the second network client.

13. The method as claimed in claim 12, wherein the pseudo-pathname includes a special name followed by an alphanumeric string encoding the NFS file handle, and wherein the method includes the file server responding to the second request to open the file by recognizing the special name in the pseudo-pathname and in response decoding the NFS file handle from the alphanumeric string.

14. The method as claimed in claim 12, which further includes the file server producing the pseudo-pathname by encoding the NFS file handle, and after writing the data to the file, sending a request including the pseudo-pathname to the second client for an anti-virus scan of the file.

15. A file server comprising:

data storage for storing a file system;

at least one data processor coupled to the data storage for accessing the file system in the data storage; and

a network interface coupled to said at least one data processor for data communication between network clients and said least one data processor;

wherein said at least one data processor is programmed for providing the network clients with access to the file system using the Network File System (NFS) protocol and the Common Internet File System (CIFS) protocol,

wherein said at least one data processor is programmed for providing a first network client with access to the file system using the NFS protocol for receiving from the first network client a name of the file and in response providing to the first network client an NFS file handle identifying the file in the file server, and for receiving from the first network client a request including the file handle for writing data to the file and in response writing the data to the file; and

wherein said at least one data processor is further programmed for providing a second network client with access to the file system using the CIFS protocol for receiving from the second network client a pseudo-pathname specifying the file, wherein the NFS file handle is encoded in the pseudo-pathname and the pseudo-pathname is used as a substitute for a pathname of the file in the CIFS protocol, and

wherein said at least one data processor is programmed to recognize that the pseudo-pathname has been used in the CIFS protocol as a substitute for the pathname and upon recognizing that the pseudo-pathname has been used in the CIFS protocol as a substitute for the pathname then decoding the NFS file handle from the pseudo-pathname and using the NFS file handle for accessing the file to enable the second client to read the data from the file.

16. The file server as claimed in claim 15, wherein the decoding of the NFS file handle from the pseudo-pathname enables said at least one data processor to locate and access the file without searching any directory of the file system.

17. The file server as claimed in claim 15, wherein the pseudo-pathname includes a special name followed by an alphanumeric string encoding the NFS file handle, and said at least one data processor is programmed for recognizing the special name in the pseudo-pathname and in response decoding the NFS file handle from the alphanumeric string.

18. The file server as claimed in claim 15, wherein the pseudo-pathname includes a special name, said at least one data processor is programmed for recognizing the special name for recognizing that the pseudo-pathname has been substituted for the pathname in the CIFS protocol, and the special name is the name of a pseudo-directory of the file system, the pseudo-directory is not contained in the data storage of the file server, yet said at least one data processor is programmed with an operating system for successfully executing a command to set a current directory for command interpretation to the pseudo-directory so that NFS file handles are decoded from pathnames in subsequent operating system commands.

19. The file server as claimed in claim 15, wherein said at least one data processor is further programmed for responding to termination of access of the first client to the file by encoding the NFS file handle to produce the pseudo-pathname, and sending a service request including the pseudo-pathname to the second network client.

20. The file server as claimed in claim 15, wherein said at least one data processor is programmed for responding to modification of data of the file by producing the pseudo-pathname by encoding the NFS file handle, and sending a request including the pseudo-pathname to the second network client for an anti-virus scan of the file.