US Patent 7454405 File management program, file management process, and file management apparatus

A file management program which enables efficient access to data in a directory file by utilizing an extent-based data access structure. When a processing request containing the name information for a file to be processed is inputted, a hash-value generation unit applies a predetermined hash function to the name information, and generates a hash value of the file to be processed. Next, a physical-block-number acquisition unit looks up a hash-value-range table, extracts hash-value-range information, and acquires a physical-block number from the hash-value-range information, where a hash-value range containing the hash value of the file to be processed is included in the hash-value-range information. Then, a directory processing unit acquires from a physical block in a storage device data corresponding to the acquired physical-block number, and performs processing of the data according to the processing request.