
A small trail through the Linux kernel (2001) - mmorearty
https://www.win.tue.nl/~aeb/linux/vfs/trail.html
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andyjpb
That's great!

If you're interested in more detail about how a VFS (Virtual File System; the
bit where it finds the file and then finds the data in the file) works,
Chapter 17 (Another Level of Indirection) in Beautiful Code
([http://shop.oreilly.com/product/9780596510046.do](http://shop.oreilly.com/product/9780596510046.do)
) is well worth a read.

It explains how the VFS in FreeBSD works. How disks, partitions, volumes,
filesystems, offsets, etc all get orchestrated together so that the Unix
"single directory hierarchy" abstraction works as intended even tho' the
actual data may be spread around a number of locations (both local and
remote).

The concepts and ideas are largely applicable to other Unixes and Unix-like
operating systems.

It's also a great example of how elegantly one can express polymorphic code,
even in plain C.

------
mmorearty
I stumbled across this, and it's nice. It's a very straightforward walkthrough
of what happens when a small program calls open() and then read().

If you look up today's Linux source code, the code has of course evolved and
is a bit more complex, but not a lot more. The nice thing about the 2001 code
is that it's still dead-simple.

