Content Addressable Storage Provider in Linux

Permission to make digital/hard copy of part or all of this work for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial advantage, the copyright notice, the title of the work, and its date appear, and notice is given that copying is by permission of the author. To copy otherwise, or republish, to post on a server, or to redistribute to lists, requires prior specific permission of the author and/or fee. (Opinions expressed by the author do not necessarily reflect the official policy of Denison University.) An operating system is a computer program that acts as intermediary between a user of the computer and the computer hardware. The computer hardware provides the primitive computing resources such as memory and input/ output (via keyboard, monitor, printer, mouse, etc.). Computer users run application programs such as word processor, computer games, web browsers and many others on top of the operating system. All of these application programs compete for the computer's resources (refer to Figure 1). The operating system manages the use of these various resources by the running user application programs. For example saving a file results in system call, which invokes the operating system. Special operating system routines called exception handlers are executed in order the file to be saved before control is returned to the user application. There are many different operating systems in use today, such as Windows, Mac OS, UNIX and Linux. They differ in structure and implementation, but they all perform the same function – to provide a convenient environment for user applications. 2 Figure 1. Abstract view of the components of a computer system Computer programs are written in a high-level language. The high-level language program is then compiled into low-level machine language code that the computer can execute. Modern operating systems are also written in high-level languages. Linux is an example of an open source operating system. Open source means that the high-level source is freely available to everyone to view and modify. This paper is concerned with kernel development for the Linux operating system. By kernel development we mean the addition of new features to the operating system by writing new source code and incorporating it within the already existing code of the operating system. Specifically we develop a new file system for Linux. A file system is a key ingredient of …