On Thu, Jan 14, 2010 at 11:16:29PM +0100, Sven Eschenberg wrote: > Hi Arno, > > What I was trying to say, I think the current behavior usually should do > a good job, when there is only one device inode (as expected). Ok. > 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 outdated configuration maybe?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. Anyways, I will just look up major and minor numbers manually until cryptsetup either reports all matching in /dev/ or has a preferred device for a major/minor combination. > Regards > > -Sven > > > Arno Wagner schrieb: >> Hi Sven, >> >> On Thu, Jan 14, 2010 at 07:18:50PM +0100, Sven Eschenberg wrote: >>> Hi Arno, >>> >>> Agreed. >>> >>> Concerning the actual problem: This should not go into cryptsetup, >>> it's not the right place. >> >> Well, it is actually already in there, just at the moment it gives you >> the first it finds. I think it is acceptable to have >> it in there, as cryptsetup already is a frontend. Writing a frontend >> for a frontend is a bit redundant. >> >>> If we talk convetions, then the convention is: There is only ONE >>> inode representing the device under /dev. If your hotplug manager >>> (and it's configuration) creates multiple such entries, it is an >>> indication for misconfiguration (imho). I.E.: Each device should >>> have one physical identification (the inode carrying major:minor, >>> together with the pathname) and as many logical names (via softlinks) >>> as wanted. This guarantees that the right pathname can be found (not >>> only for dmcrypt btw) and the device is yet useable via it's >>> symbolic names (i.e. UUIDs, volume labels etc.). >>> >>> If the preference of the system administrator is on UUID names, then >>> those should be created as device files, and the 'traditional names' >>> as softlinks. If yet there is a need to know all device names that >>> link to a certain major:minor, then this can and should be done in a >>> simple shell script, where it belongs in my opinion. >>> >>> Just my 2 cents >> >> I agree to that. It came when I added udev to my system, which >> I do not like, and it creating devices under /dev/scsi/ is the >> default under Debian. Clearly this has not been thought through. >> As such broken configs can happen and it seems easily, it seems >> they need to be expected. >> >> Arno >> >> >> >> >>> Regards >>> >>> -Sven >>> >>> >>> >>> Arno Wagner schrieb: >>>> 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. >>>> >>>> Arno >>>> >>>> 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. >>>>>>>> >>>>>>> _______________________________________________ >>>>>>> dm-crypt mailing list >>>>>>> dm-crypt@xxxxxxxx >>>>>>> http://www.saout.de/mailman/listinfo/dm-crypt >>>>>>> >>>>> _______________________________________________ >>>>> dm-crypt mailing list >>>>> dm-crypt@xxxxxxxx >>>>> http://www.saout.de/mailman/listinfo/dm-crypt >>>>> >>> _______________________________________________ >>> dm-crypt mailing list >>> dm-crypt@xxxxxxxx >>> http://www.saout.de/mailman/listinfo/dm-crypt >>> >> > > _______________________________________________ > dm-crypt mailing list > dm-crypt@xxxxxxxx > http://www.saout.de/mailman/listinfo/dm-crypt > -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@xxxxxxxxxxx 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 _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
