This is a heavily commented, very simplistic filesystem module for the Linux kernel. It's intended as a living tutorial of sorts for the Linux virtual filesystem (VFS) and how filesystems work.
To make use:
make -C /usr/src/linux-headers-2.6.32-23-generic/ SUBDIRS=$PWD
modules`
(or just make, with the accompanying Makefile)
To load use:
sudo insmod vvsfs.ko
(may need to copy vvsfs.ko to a local filesystem first)
To make a suitable filesystem:
dd of=myvvsfs.raw if=/dev/zero bs=512 count=100
./mkfs.vvsfs myvvsfs.raw
(could also use a USB device etc.)
To mount use:
mkdir testdir
sudo mount -o loop -t vvsfs myvvsfs.raw testdir
To use a USB device, create a suitable partition on USB device (exercise for reader)
./mkfs.vvsfs /dev/sdXn
where sdXn is the device name of the usb drive, then do:
mkdir testdir
sudo mount -t vvsfs /dev/sdXn testdir
Use the file system:
cd testdir
echo hello > file1
cat file1
cd ..
Unmount the filesystem:
sudo umount testdir
Remove the module:
sudo rmmod vvsfs