HEADS UP NetBSD lvm support

[Adam Hamsik <haaaad%gmail.com@localhost>]

Hi folks,

Today I have committed couple of changes to haad-dm branch. With these
latest changes I was able to use lvremove, lvextend, lvreduce etc..

I believe that haad-dm is currently in a good shape and it only needs
more testing to fix all possible outstanding bugs. for all brave testers
I have created new chapter in NetBSD Guide about lvm support [1].

Instructions how to test lvm:

1) update src/sys and src/external to haad-dm branch.
2) if you kernel supports new modules build new module in src/sys/ 
modules/dm or
   build new kernel with this line pseudo-device   dm line. Load  
module/ reboot new kernel.

3) build lvm2tools and libdevmapper in src/external/gpl2/ and install  
them.

4) use tools lvm to manage your lvm devices.

   lvm pvcreate /dev/raw_disk_device # create Physical Volume *

   lvm vgcreate vg00 /dev/raw_disk_device #create Volume Group-> pool  
of available disk space.

   lvm lvcreate -L20M -n lv1 vg00 # create Logical volume aka Logical  
disk device

   newfs -F -s 20M /dev/vg00/rlv1 # newfs without -F and -s doesn't  
work

   mount /dev/vg00/lv1 /mnt # Enjoy

   After reboot you can activate all existing LV in system with  
command.

   lvm vgchange -a y

   You can use

   lvm lvdisplay vgdisplay pvdisplay to see at status of your LVM  
devices.

   You can also use lvm lvextend/lvreduce to change size of LV.

   I haven't tested my driver on SMP system there are probably some  
bugs in locking
   so be aware of it :) and do not try to extend/reduce partition  
during IO
   (something bad can happend).


   TODO:

   1) review locking I will probably allow only one ioctl call to be  
inside dm driver
      at time.

   2) Write snapshot driver only skeleton was written yet.

   3) Add ioctls needed to correct newfs functionality. I tried to  
implement them
      in device-mapper.c::dmgetdisklabel but it doesn't work still.

   4) Write lvm rc.d script to enable LVM before disk mount so we can  
use lvm for
      system partitions.


* If you are using disklabel partition a as raw_disk_device it MUST  
start after disklabel
  blocks. Offset of a partition should be 65s.


P.S. I will not be able to answer any bug mails till sunday.

[1]http://www.netbsd.org/~haad/lvm_doc.diff

Regards

Adam.