Method and apparatus for file server addressing

• US 5,742,817 A
• Filed: 12/08/1995
• Issued: 04/21/1998
• Est. Priority Date: 12/08/1995
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Pinkoski, Aiko M.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Min, Donald
• Application Number:
  US08/569,745
• Time in Patent Office: 865 Days
• Field of Search: 395/601, 395/616, 395/618, 395/610, 395/614, 395/602, 395/611
• US Class Current: 1/1
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing

Abstract

An addressing scheme for file servers. The file handle in a call that accesses a file includes a file system identification, a file identification or inode number and a generation number. The addressing system converts the multi-bit file identification number into an alternative path name that identifies a location for the file without the need for converting the real path name. In one particular embodiment the inode number in binary form is translated into a multiple digit hexadecimal form that is parsed into directory names. The last directory name provides the location of the designated file.

Claims

1. In a file system in which a client pathname and a unique numerical value identify each file and in which certain operations return to the client a file handle including the unique numerical value and other operations transfer the file handle back to the file system and wherein the file system includes a first set of links for establishing correspondences between the client pathnames and unique numerical values, the improvement of alternate path addressing means for facilitating the location of a file in the file system in response to all other operations subsequent to the return of the file handle, said alternate path addressing means comprising:

(A) means for converting the unique numerical value in the returned file handle into an alternate pathname,

(B) a second set of links for establishing correspondences between the alternate pathnames and the locations of files in the file system identified by each unique numerical value; and

(C) means for obtaining the location of a file by selecting a corresponding link in said second set of links as determined by the alternate path name.

2. A file system as recited in claim 1 wherein the unique numerical value is a binary number and said converting means parses the unique numerical value into a plurality of hexadecimal values that collectively become the alternate pathname to an entry in said second set of links.

3. A file system as recited in claim 2 including a first attribute table and the file handle includes a second file identifier and wherein the improvement additionally comprises a second attribute table indexed from the unique numerical value, each entry in said second attribute table comprising a second file identifier for the corresponding file.

4. A file system as recited in claim 1 wherein the file handle includes a twenty-four binary bit unique numerical value and said converting means decomposes the unique numerical value into three-sections, each section including a two-digit hexadecimal value and said three sections defining the alternate pathname to an entry in said second set of links.

5. In a network including a client and a server interconnected by a communication link wherein the server comprises at least one file system in which individual files are organized in at least one directory for identification by client pathnames, wherein the server includes control programs located in user space and kernel space, wherein certain requests for file system operations sent from the client to the server contain client pathnames and produce file handles including a portion for specifying the server, an inode number specifying a file in the server and a file generation number, and wherein each file system includes a first set of links for establishing correspondences between client pathnames and inode numbers and an attribute table for storing certain characteristics of each file including the file generation number, the improvement of alternate path addressing means for allowing access from user space to an identified file by decoding file handles sent by all other commands subsequent to the return of the file handle, said alternate path addressing means comprising:

(A) means for receiving the returned file handle,

(B) means in the user space for converting the inode number in a received file handle into an alternate pathname,

(C) a second set of links in the file system establishing correspondences between the alternate pathname and an index node value, and

(D) a second attribute table in user space indexed from the inode number, each entry in said second attribute table comprising a file generation number for the corresponding file.

6. A network as recited in claim 5 wherein the inode number is a binary number and said converting means parses the inode number into a plurality of hexadecimal values that define the alternate pathname through said second set of links.

7. A network as recited in claim 5 wherein the inode number is constituted by a twenty-four binary bit number and said converting means decomposes the inode number into three-sections, each section including a two-digit hexadecimal value and said three sections defining the alternate pathname to an entry in said second set of links.

8. A network as recited in claim 5 wherein said improvement additionally comprises means for comparing the file generation numbers in the file handle and said second attribute table.

9. A method for addressing one of a plurality of files in a file system at a server wherein each of the files is identified by an unique numerical value and by a client pathname, wherein the file system includes a first set of links for establishing correspondences between client pathnames and the unique numerical values and wherein certain client initiated operations convert a client pathname to a file handle with the corresponding unique numerical value that is returned to the client, all subsequent client initiated operations identifying a file with the returned file handle, the method comprising the steps of:

(A) responding to the subsequent client initiated operation by converting the unique numerical value in the file handle into an alternate pathname, and

(B) retrieving the location of the file from a second set of links in response to the alternate pathname, said second set of links establishing correspondences between the alternate pathnames and the location of files in the file system.

10. A method as recited in claim 9 wherein the unique numerical value is a binary number, said conversion including parsing the unique numerical value into a plurality of hexadecimal values that form the alternate pathname to an entry in the second set of links.

11. A method as recited in claim 10 wherein each unique numerical value includes other information about each file, said method including forming for each file an entry in a second attribute table indexed from the unique numerical number, each entry in said second attribute table comprising information about the corresponding file in the file system, and validating the presented file handle by comparing the information retrieved with the unique numerical identifier and the second attribute table.

12. A method as recited in claim 9 wherein the other client operations identify a particular file with a file handle including a twenty-four binary bit unique numerical value and said conversion includes the steps of decomposing the unique numerical value into three-sections, each section including a two-digit hexadecimal value and combining the three sections into the alternate pathname to an entry in the second set of links.

13. A method for addressing a file in a server in a network including a client station interconnected to the server by a communication link wherein the server comprises at least one file system in which individual files are organized in at least one directory for identification by client pathnames and includes control programs located in user space and kernel space, wherein certain user requests for file system operations sent from the client to the server contain user pathnames and produce file handles returned to the client state for use by subsequent commands including a portion for specifying the server, an inode number specifying a file in the server and a file generation number, and wherein each file system includes a first set of links for establishing correspondences between each client pathname and inode number and an attribute table for storing certain characteristics of each file including the generation number, a method for allowing access from user space to an identified file by decoding in user space the server file handles sent by the subsequent commands comprising the steps of:

(A) receiving the file handle,

(B) converting the received file handle into an alternate pathname based upon the inode number,

(C) retrieving from a second set of links the contents of a storage location identified by the alternate pathname containing information about the inode number,

(D) retrieving from an entry in a second attribute table indexed from the inode number, each entry in the second attribute table including the file generation number for the corresponding file, and

(E) validating in user space the received file handle by comparing the file generation number in the file handle with the file generation number from the entry in the second attribute table.

14. A method as recited in claim 13 wherein the inode number is a binary number, said conversion parsing the inode number into a plurality of hexadecimal values that become the alternate pathname to a location in the second set of links.

15. A method as recited in claim 13 wherein the inode number is constituted by a twenty-four binary bit number and said conversion decomposes the inode number into three sections, each section including a two-digit hexadecimal value and defines the alternate pathname to the entry in the second set of links using the three sections.