Research And Implementation Of Embedded Linux File System

With the rapid development of the embedded systems, embedded Linux also has been witnessing wider application in various embedded fields. Linux has a concise and highly efficient kernel, a good networking performance and a good support for multiple processor platforms. And more importantly, Linux originates from UNIX and therefore has abundant well-trained developers and development resources. All these contribute to the rapidly increasing application of Linux in embedded fields.Compared with the file systems in other operating systems, Linux file system has two important features. The first is the VFS that is introduced into Linux to provide support for multiple different file systems. The second one is that various kinds of file systems can easily be mounted to or unmounted from the Linux file system tree. VFS is the basis of all the file systems in Linux environment. Therefore, if we want to have a deeper understanding about Linux and its file system and build a suitable embedded Linux system, it is of great significance to understand how VFS works and how to support new file systems on the basis of VFS.At present, most research papers about Linux file system focus on the typical file system application while only few touches the subject of VFS, the core mechanism of Linux file system, and how to build support for new file system on the basis of VFS. This dissertation focuses on the research of Linux file system by combining the theory analysis with the experiments together. First, It starts from the analysis of VFS, the Linux file system hierarchies, the file system model of the VFS and various kinds of VFS file system objects. It then goes on the research on how to support new file systems using VFS based on the analysis of VFS and the knowledge of the mechanism of other kernel core components.Then, The NEFS file system is put forward to illustrate the issues that should be considered when a new disk file system is designed. The design process of NEFS file system is also introduced afterwards. In order to reach the goal of high efficiency and low cost, some improvements have been introduced to the NEFS file system according to the actual requirements and situations of the embedded systems. Actually, the NEFS file system device driver is written and tested in real embedded Linux environment to test the research.Finally, three typical file systems in Linux environment, that is, the disk file system, network file system and the special (or virtual) file system, are picked out for the analysis about their typical use in building embedded Linux system.