building the KPL filesystem    Kees Cook (cook@cpoint.net)

9/25
think about how you want it to work
make basic structures
write skeleton linux VFS code (and structures)
implement "read_super" to return the VFS superblock for the FS,
	including the super_operations

read_super is given:
	a ptr to the VFS sb to fill in
	VFS sb contains:
		s_flags  (for mount flags)
		s_covered (the inode being covered by the mount)

read_super must:
	increment MOD count
	lock_super
	fill in the VFS sb:
		s_blocksize
		s_blocksize_bits
		s_magic
		s_dev
		s_op
		s_mounted	// the VFS inode for the root dir
		s_dirt
	initialize everything it needs for it's data structures
		(can use s_generic_sbp in VFS sb)
	unlock_super

filling in s_op gives the VFS the following abilities:	
	umounting (with "put_super" func)
	accessing inodes (with "read_inode")
to see the root directory, though, it needs the inode_operations for dir:
	readdir (with "readdir" func)


read_inode is given:
	VFS inode to be read

read_inode must:
	fill in the VFS inode:
		i_mode
		i_uid
		i_gid
		i_nlink
		i_size
		i_mtime
		i_atime
		i_ctime
		i_blocks
		i_blksize = PAGE_SIZE
		i_version = ++event   (scheduler event count)
		i_op    // depends on filetype!
		set rdev (for block & char filetypes)
		set any flags
	initialize any data


readdir is given:
	VFS inode
	VFS file
	VFS dirent
readdir must:
	wander through the directory
	find next after VFS file's position
	call dcache_add
	call filldir with dirent  with as many dir entries as we like??

9/27
put_super is given:
	VFS sb to umount
put_super must:
	lock_super
	s_dev = 0
	free any structures allocated
	mark super buffer dirty?
	brelse super buffer
	unlock_super
	decrement MOD count


VFS call mappings
-----------------
9/25
iget	s_op: read_inode
iput	s_op: write_inode
namei	i_op?: lookup


Cool Stuffs
-----------------
9/25
	event  long    (from sched.h)
	CURRENT_TIME   (dunno)
	dcache_add(VFS ino*dir, char * name, int len, ino#)  (for sys readdir)