LYFS - A simple kernel file system example run in 4.* version Linux.

Important Tips!

• The example can only be used to study. It can not work as tools. The author has no reponsibilty to your file & device damage.
• The code has been tested in linux-4.4.
• If you met some errors, please contact QQ 934367813 or QQ group 479198558.

How run it?

• Makefile file own KDIR variable. Please make sure it is configured to your kenel header directory.

KDIR := ~/compile/linux-4.4

• Jump to the source dir. Excute make build command to compile the module. Then, make sure there exists lyfs.ko module file.

• Excute make mount. It will insmod, and mount output/disk.img to output/point. output/disk.img has been formated, it contains some files. Of course, you can run mkfs.lyfs to format the img file. Excute touch to create file.

• Now you can operate the mounted file system as you want. Excute echo to write some string into one file and excute cat to read the file.

• Now, you can unmount the file system and remove the module from your system.

LYFS architecture

super_block:
	every_block is 4KB.
	super_block has 4KB.
	first meta is root. it has no parent and name.
	meta_area is from 4KB.
	partion_size [4B]
	meta_area size = .
	block_area index.

meta_area:
	file name has 16 char. [16B]
	is file or dentry. [1B]
	block_area index. [4B]
	parent meta_are index.[4B]
	16 child meta_are index. [4B * 16]

data_area:
	file_size. [4B]
	....
	next block index [4B]


----------------------------------------------------------------------
|				|			  |			   |			 |			 |
|  super_block	| meta_bitmap |	meta_area  | data_bitmap | data_area |
|				|		 	  |			   |			 |			 |
----------------------------------------------------------------------