Bug#581593: udev: kernel-provided name 'dm-0' and NAME='/mapper/sdb2_crypt' disagree

Peter Rajnoha prajnoha at redhat.com
Mon May 17 11:51:15 UTC 2010


On 05/15/2010 12:35 PM, Sheridan Hutchinson wrote:
> In the interim is there any known work-around for this?
> 
> It's a bit of a jip because my / file system initially mounts as read only.
> 

Well, it should be just a warning, it shouldn't break anything.
As for the warning message removal, the only right way is to
create nodes as /dev/dm-X and then symlinks in /dev/mapper,
so changing that one line in the 55-dm.rules:

  ENV{DM_NAME}=="?*", NAME="mapper/$env{DM_NAME}", SYMLINK+="$kernel"

and use this instead:

  ENV{DM_NAME}=="?*", SYMLINK+="mapper/$env{DM_NAME}"

(this is what we had to agree on with udev team once)

As for the suppression of the ADD event, we don't have a clear
solution for this yet, discussions still ongoing. The problem is that
device-mapper devices should be visible under /dev only when the
table is loaded and made live - and that's on CHANGE event
(the ADD event is generated automatically outside of device-mapper
in kernel, we're not in control of this event at all).

On the other hand, we have "udevadm trigger --action=add" used
mostly at boot. That's the "ACTION=="add", ENV{STARTUP}!="1"..."
rule that's in 55-dm.rules as well that tried to provide a way
to use this trigger for dm devices when needed (but still, it required
the "STARTUP" variable to be set).





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