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A method for optimal open file handle re-use in a client-server file system

IP.com Disclosure Number: IPCOM000238418D
Publication Date: 2014-Aug-26

Publishing Venue

The IP.com Prior Art Database

Abstract

· A method for re-using fid (file handles) returned by server among local application open requests on the client by optimal fid (file handle) array approach. · A method for closing re-usable fids (file handles) on server on local application close requests on the client by optimal fid (file handle) array approach. · A method for re-using fid (file handles) returned by server among local application open requests on the client by simplistic fid (file handle) array approach. · A method for closing re-usable fids (file handles) on server on local application close requests on the client by simplistic fid (file handle) array approach.

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A method for optimal open file handle re -use in a client-server file system

Title: A method for optimal open file handle re -use in a client-server file system Problem Statement:

    An SMB client system provides access to remote files and allows various operations on them to the requesting applications by interacting with SMB server as per the protocol specification (using required protocol version negotiated).

    Request to open a file with required access modes is one of the file operations. There is a requirement to manage application file open requests to the SMB client system mapping with corresponding file open requests over the SMB server with an optimal method.

Use Case:

    Let us consider a case where there are multiple file open requests from different applications to the SMB client system for the same file on the same remote share connect (called tree connect in SMB protocols).

    These requests could be for various different operations to be performed later, like read, write, execute along with different options like read-sharing only for opens, no-sharing for other opens, or with no such sharing restrictions. The required accesses for the file open along with sharing restrictions are provided as the input.

    These application open requests require SMB client system to interact with SMB server, to open the file on the server with required access modes and sharing restrictions, so appropriate fid (file handle) returned by the server can be used for corresponding file operations later (that is read, write, execute etc).

    A solution to address above requirement with optimal number of interactions with the server is discussed in this invention.

    An optimal solution to address the above mentioned requirement is discussed in this invention.

Prior Art:

    There does not seem to be a prior art for the requirement in our knowledge. However there is an obvious/trivial solution to the problem discussed.

    For every application file open request on SMB client system, it should communicate with the SMB server to perform corresponding file open on the server for given access modes and sharing restrictions. The resulting fid returned by the server need to be stored as part of file-open specific data and used whenever any operation (like read, write, execute etc) is requested over this file-open.

    For example, in a file-system interfaced implementation, like virtual file sytem of SMB client, it can be stored in open file table at the logical file system layer.

The disadvantage with this approach is every application file open request results in a SMB message send and receive for the SMB client system.

References: i. SMB protocol specifications

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ii.File open vnode operation in AIX

This has been implemented for AIX General Availability release in 2014 - 71Q Prototype is available at :

/gsa/ausgsa/projects/c/cjhs/india/cifs/prototype

    There are two possible solutions to the problem statement discussed here. One is a simplistic fid (file handl...