UNIX Filesystems: Evolution, Design, and Implementation

Summary

In the 1980s and early 1990s, there was a lot of consolidation around the Sun VFS/vnode interface with many of the commercial UNIX vendors adopting the interface to some degree. This architecture has still remained largely intact with only a few changes over the last decade.

The Linux kernel has seen a huge amount of change over the last few years with the VFS layer still in a state of flux. This is one of the few operating systems that still shows a huge amount of new development and has by far the largest number of filesystems supported.

By looking at the different filesystem architectures, one can see a large degree of similarity among them all. After the basic concepts have been grasped, locating the structures that pertain to filesystem implementations and following the code paths to get a high level overview of how filesystems are implemented is a relatively straightforward task. Therefore, readers new to operating systems are recommended to follow the earlier, more compact implementations first.