[pkg-cryptsetup-devel] Bug#538221: [codesite-noreply at google.com: Issue 34 in cryptsetup: Command failed: device-mapper: create ioctl failed: Device or resource busy]

[Jonas Meurer]

hey,

On 03/09/2009 Stuart Pook wrote:
> On 27/08/09 23:51, Jonas Meurer wrote:
> 
> >you try to luksOpen the device twice, first the lvm volume, and then the
> >lvm snapshot. This is blocked by cryptsetup. You can overwrite the block
> >by adding the commandline option '--non-exclusive' to second luksOpen,
> >but be aware that might lead to other problems. It should be save with
> >--readonly though.
> 
> yes but I need both the device and its snapshot to be read-write. If I
> start kvm on the snapshot with the options '--non-exclusive' &
> --readonly I get
> 
> [   14.816120] end_request: I/O error, dev vda, sector 1125
> [   14.817642] Buffer I/O error on device vda1, logical block 531
> [   14.819587] lost page write due to I/O error on vda1
> 
> So I luksOpen the device normally and the snapshot with
> --non-exclusive. I hope that this will not do anything bad to my kvm
> virtual machines which have their roots on snapshots.

this should be save as snapshot and origin are indeed two different
devices. the problem here is another one which will be adressed in the
next cryptsetup release.

> As you say, the usage for cryptsetup says "--non-exclusive Allows
> non-exclusive access for luksOpen, WARNING see manpage" but there is
> nothing in the man page. I had a quick look at
> http://code.google.com/p/cryptsetup but could not find anything there
> either. I'll look again when I can.

yes, and the --non-exclusive option will be dropped with the next
release of cryptsetup. instead a new option --disable-uuid will be
introduced for cloned/snapshoted LUKS devices.

for more information see the upstream issue at
http://code.google.com/p/cryptsetup/issues/detail?id=34

greetings,
 jonas
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