Re: [dm-crypt] renaming of device

[Arno Wagner <arno@wagner.name>]

On Fri, Jan 15, 2010 at 03:17:25AM +0100, Sven Eschenberg wrote:
> Arno Wagner schrieb:
>> On Thu, Jan 14, 2010 at 11:16:29PM +0100, Sven Eschenberg wrote:
>>> Hi Arno,
>>
>>> Concerning udev - you could either modify the configuration for the 
>>> scsi  subsystem, or you could copy it to you own rule file modify it 
>>> and  override debian's defaults.
>>>
>>> This ways you are a little safer, when the distribution modifies some 
>>>  rules (for some odd reason) and are sure that dmcrypt returns the 
>>> name  you expect. In general this is true for most device names where 
>>> you have  special needs.
>>>
>>> On my debian there are no rules for creating /dev/scsi/* names, at 
>>> least  not for scsi disks. Might be you are stuck with an older udev 
>>> or some  outdated configuration maybe?
>>
>> I don't know and do not really have time to investigate now.
>> Come to think of it, it could also have some connection to a
>> recent kernel upgrade, I am running 2.6.32.2 from kernel.org.
>> I did not notice the issue before, so maybe the kernel now also
>> creates device files and there was something about a device
>> pseudo filesystem or the like in the patchnotes.
>
> Ah, I guess you unfortunately actiavted kernel managed tmpfs in /dev,  
> which is an experimental feature. Check for CONFIG_DEVTMPFS in your  
> kernel config, I bet it is turned on.

Good idea, but no. Must be something in the udev configuration
after all. Not that I found anything. Or anything in the logs.
Hmm. Oh, well. It is not that important. But I really hate this
badly documented obscure "automagical" stuff. As soon as anything
breaks, it really sucks. 

On the side of where cryptsetup finds the device for a specific
major and minor number, it is indeed a simple recursive directory
traversal. Unfortunately it is in libdevmapper.c, i.e. in the 
system lib of that name. That means it cannot easily be changed.

Arno

-- 
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@wagner.name 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier