[dm-crypt] renaming of device

Arno Wagner arno at wagner.name
Wed Jan 13 18:29:46 CET 2010

Well, I think listing all in /dev/ would be an improvement to
the current behaviour. Of course people can put their device
spceials somewhere else, but that is a pretty big break of
convention that IMO does not need to be supported.


On Wed, Jan 13, 2010 at 05:18:27PM +0100, Sven Eschenberg wrote:
> Hi Arno,
> Indeed cryyptsetup traverses /dev stating each file for major:minor and  
> stops on the first match - at least a trace suggests this. The question  
> is though, if this is an appropriated approach. One thing that annoys me  
>  when doing this: There's no guarantee that device inodes are in /dev,  
> nor links to it. In theory it cann be any place in the filesystem. there  
> can be as many links as you want and as many inodes for the same device,  
> as you want.
> Regards
> -Sven
> Arno Wagner schrieb:
>> Having had a bit of time to think about it, it seems that
>> it would indeed be necessary to store the device name.
>> A possible alternative is to traverse all of /dev/ and
>> report all devices that match major/minor. This may be
>> the solution causing the least effort, as cryptsetup
>> is doing something like it already, just that it currently
>> stops after the first match.
>> In fact, I think I prefer for it to report all devices
>> that match. 
>> Arno
>> On Wed, Jan 13, 2010 at 11:20:36AM +0100, Sven Eschenberg wrote:
>>> Hi Luca,
>>> I doubt this is possible. The only possible thing would be: Modify DM,
>>> when a device name is passed in, to keep the passed in name alongside
>>> the actual major:minor and provide an IOCTL, to access the information.
>>> Regards
>>> -Sven
>>> On Wed, 2010-01-13 at 08:01 +0100, Luca Berra wrote:
>>>> On Sun, Jan 10, 2010 at 09:33:13PM +0100, Milan Broz wrote:
>>>>> The algorithm is very simple (and was probably written before
>>>>> udev was used so these special links in /dev did not exist).
>>>>> So it need to add some preferred names and not print the first entry.
>>>>> Please can you add an issue to project pages to not forget about this?
>>>>> Probably good idea to fix it in next minor release.
>>>> it could be useful to have the functionality in device-mapper itself,
>>>> instead of duplicating in dm-crypt, lvm, dmraid, whatever ?
>>>> Regards,
>>>> L.
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Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno at wagner.name 
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