Re: udev lvm permisions

[Michal Soltys <soltys@ziu.info>]

Geert Geurts wrote:
> 
> I've created this rule but it applies to the kernel device... /dev/dm-*.
> What I need is a rule that changes the ownership
> of /dev/mapper/HomeVolume.
> 
> Thats where I stand now,
> so any suggestions are welcome!
> 

As I corrected myself earlier - if you really need udev to do so, you 
need rules file that will create the names as lvm would do.

Or you can extend a bit the above rules and make udev create that 
particular device with the name you want, e.g.

ENV{DM_UUID}="<uuid>", NAME:="<something>" GROUP="users", MODE="0660"

This guarantees that no rule later will alter the name. It also assumes 
you're using udev>\x131 and nothing earlier did NAME:= (with 130 and 
earlier, any earlier NAME= or NAME:= assignment was final).
Then - just use /dev/<something> to access your volume however you need.

Or ... you can just add simple chown / chmod somewhere after lvm is 
activated (not very flexible, but definitely simple).


Anyway - I needed similar thing at one of my machines, where squid cache 
uses coss storage. Squid runs unprivileged, but had to access coss 
device directly. I use rules mimicking lvm/dmsetup behaviour though, so 
simple NAME= test was enough in my case. If you're curious - 
http://marc.info/?l=linux-hotplug&m\x122165542423023&q=p3

With that, I have
ACTION="add|change", SUBSYSTEM="block", NAME="mapper/vg0-coss", \
OWNER="squid", GROUP="squid"

Good luck