Re: [dm-crypt] Avoiding fsck.ext4 destruction of crypto_luks data

[Arno Wagner <arno@wagner.name>]

On Sun, Dec 30, 2012 at 01:25:46PM +0100, Milan Broz wrote:
> On 12/30/2012 01:08 PM, Sven Eschenberg wrote:
> >> I also found that "wipefs"
> >> does not remove matadata 0.90 signatures from md components (located
> >> at the end. I still use them because I like kernel-level autodetection
> >> and my arrays are small), also added warning about that.
> 
> Usual util-linux maintainer response is "send a patch" :-)
> 
> wipefs must work (e.g. anaconda installer depends on the proper sig. erase)
> so it is a bug somewhere.
> 
> Do you have reproducer? (only 0.9 metadata end-of-disk format?)

Reproduce with (adjust loop2 and md12 numbers as needed):
------
head -c 1M /dev/zero > t
losetup /dev/loop2 t
mdadm --create --metadata=0.90 --force -l 1 -n 1 /dev/md12 /dev/loop2
mdadm --stop /dev/md12
mdadm --examine /dev/loop2
  --> Raid componend with intact magic
wipefs /dev/loop2
mdadm --examine /dev/loop2
  --> same as above, RAID signature still there
------

Version (Debian stable): util-linux: 2.17.2-9

Arno
-- 
Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
----
One of the painful things about our time is that those who feel certainty
are stupid, and those with any imagination and understanding are filled
with doubt and indecision. -- Bertrand Russell