Summary
As the example filesystem here shows, even with the most minimal set of features and limited operations, and although the source code base is small, there are still a lot of kernel concepts to grasp in order to understand how the filesystem works. Understanding which operations need to be supported and the order in which they occur is a difficult task. For those wishing to write a new filesystem for Linux, the initial learning curve can be overcome by taking a simple filesystem and instrumenting it with printk() calls to see which functions are invoked in response to certain user-level operations and in what order.
The uxfs filesystem, although very limited in its abilities, is a simple filesystem from which to learn. Hopefully, the examples shown here provide enough information on which to experiment.
I would of course welcome feedback so that I can update any of the material on the Web site where the source code is based:
www.wiley.com/compbooks/pate
so that I can ensure that it is up-to-date with respect to newer Linux kernels and has more detailed instructions or maybe better information than what is presented here to make it easier for people to experiment and learn. Please send feedback to spate@veritas.com.
Happy hacking!
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