F.P.
sorry for this long and may be OT post
hd partitions is a hardware bug
LVM is a thing that is a level higher that hd partitions
can some body point my to souch thing:
it must be mountable with mount, and must connect mounted
filesystem according some rules in to one filesystem(mount point)
(like lvm combines hd partions in one and splits by rules
sorry if I'm not so correct as is it, am'not familiar with lvm)
as example1: I have hda1 hda2 and mount them to /mnt/hda1 with ext2
and /mnt/hda2 with umsdos, first and second mount points are normal
capable dirs, and I wona have all this space in one place as /mnt/one
simple combine two dirs in one, how share dirs and files between
is a rule task
second example(that actualy is my interest) is:
if I have mounted in prev example /mnt/hda1 as read only
and /mnt/hda2 as rw then I combine two dirs in one
/mnt/one
simple rule for this case may be if opens /mnt/one/somefile
first search it as /mnt/hda2/somefile if not found
in /mnt/hda1/somefile
second rule is that when try to write to /mnt/one/somefile
and it is open from /mnt/hda1 (that ro is) make a copy
of this file on /mnt/hda2/somefile, open from this location
and write to it
this allows to have some data on cd as example and update
of this data on hd
I know AVFS but it works not as mountable filesystem but as some hack
and to do rule from second example, it must be great work(may be)
--------questions---------
how i can do that i have a lot of files on cd and there modifyed
versions on hdd, and as result I'm using uptodate data
(I think about cd based linux and i know some projects, but it's
all ~1g to download and have some packages that i won't and not have
packages that i wona. I can install on hdd packages that i wona
and burn it on cd, but from beginning i must known what and how
it must be config'd, and this config must be for all cases
it is impossible) and it is a way to have small part of data
on each machine where i'm using cd based linux, with config
that for this machine actual is
second possibility that i see is to easy to convert every rw
mountable filesystem to ext2 comparatible, as umsdos do it to
msdos filesystem
another possibility is to get for each process and user own view
of root tree. I see it as usefull, as example each user can
have own pap and chap secrets in same place /etc/ppp
going somewhere a project that have properties that I have tryed to
describe
Or some place where I can found answer to : how to from module
that is mounted to some mount point get access to file
from another filesystem (i have looked some kern and modules
src but ansver to the question is not so clear for my, how make it
rigth way)(better as working example, or some docs to this topic)