IBM’s DeveloperWorks site has an up-to-date, concise explainer about the Linux file system up today that’s worth a quick read, for refresher’s sake.
When it comes to file systems, Linux is the Swiss Army knife of operating systems. Linux supports a large number of file systems, from journaling to clustering to cryptographic. Linux is a wonderful platform for using standard and more exotic file systems and also for developing file systems. This article explores the virtual file system (VFS)—sometimes called the virtual filesystem switch—in the Linux kernel and then reviews some of the major structures that tie file systems together.
It covers all the basics (and I mean BASICS; example of a header found within: What is a file system?), and then goes into the technical stuff after that. Like I said, worth a quick read when you get the chance!