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Re: [lvm-devel] lvrename changes link to direct /dev/dm-X



Dne 29.8.2013 11:54, Oliver Rath napsal(a):
Hi list,

I was able to reproduze the renaming issue on a gentoo-machine with lvm-git:

heimserver ~ # lvcreate --name myoriginal -V 10M -T dmivg/winthinpool
   Rounding up size to full physical extent 12,00 MiB
   Logical volume "myoriginal" created
heimserver ~ # ls -l /dev/dmivg/myoriginal
lrwxrwxrwx 1 root root 28 29. Aug 11:46 /dev/dmivg/myoriginal ->
/dev/mapper/dmivg-myoriginal

So Gentoo has broken udev rules as well probably.
Links created by proper udev rules should be pointing directly to /dev/dm-x


Have you been compiling lvm2 yourself ?

Have you configured lvm2 package with --enable-udev_rules?
(it's not enabled by default)

Isn't there any udev falback running in this system ?

Isn't device activated without udev?

In pre-udev  era all dm nodes have been created in /dev/mapper subdir.
So lvm created links pointing to this place.

With  udev  all dm nodes are by default created as  /dev/dm-xx and all
the links in /dev/mapper & /dev/vgname/lvname  are pointing directly
to this node - but that require proper udev rules and properly configured system - I'd recommend to test with i.e. Fedora.

Unfortunately systems like Debian are using non-upstream udev rules
from maintainer which are reinventing them based on some unknown rules to us...


heimserver ~ # lvrename /dev/dmivg/myoriginal myrenamedoriginal
   Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
heimserver ~ # ls -l /dev/dmivg/myrenamedoriginal
lrwxrwxrwx 1 root root 8 29. Aug 11:47 /dev/dmivg/myrenamedoriginal ->
../dm-13
heimserver ~ # ls -l /dev/mapper/dmivg-myrenamedoriginal
lrwxrwxrwx 1 root root 8 29. Aug 11:47
/dev/mapper/dmivg-myrenamedoriginal -> ../dm-13


It seems, that after renaming the link points directly to the /dev/dm-X
device, before that he linked to the link in /dev/mapper/..

Well as long as the point to the proper device at the end - it's at least usable - but it's clear the udev dir has been probably touched by fallback rules (which are there for cases, udev is failing to do proper thing)


root asterisk:~# ls -l /dev/mapper/dmivg-myoriginal
lrwxrwxrwx 1 root root 8 Aug 29 11:50 /dev/mapper/dmivg-myoriginal ->
../dm-55
root asterisk:~# lvrename /dev/dmivg/myoriginal myrenamedoriginal
   Renamed "myoriginal" to "myrenamedoriginal" in volume group "dmivg"
   Unable to rename device node from 'dmivg-myoriginal' to

Udev rules are not doing what they supposed to do....

'dmivg-myrenamedoriginal'
root asterisk:~# ls -l /dev/dmivg/myrenamedoriginal
lrwxrwxrwx 1 root root 35 Aug 29 11:51 /dev/dmivg/myrenamedoriginal ->
/dev/mapper/dmivg-myrenamedoriginal
root asterisk:~# ls -l /dev/mapper/dmivg-myrenamedoriginal
brw------- 1 root root 252, 55 Aug 29 11:51
/dev/mapper/dmivg-myrenamedoriginal
root asterisk:~#

Here the device twice: in /dev/dm-55 _and_ in
/dev/mapper/dmivg-myrenamedoriginal

@Zdenek: if you need a -vvvv log, please tell me.

If you have been compiling lvm2 yourself - you could replace upstream rules with those placed in Debian.

I guess the only real solution here would be to build Debian package by some lvm2 team member since the package in Debian is probably broken.

Zdenek


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