[Pkg-libvirt-maintainers] Bug#748120: Bug#748120: Improper device checking with virt-clone on LVM

[Guido Günther]

Hi,
On Wed, May 14, 2014 at 03:52:47PM +0200, Kwadronaut-debian wrote:
> Package: virtinst
> Version: 0.600.1-3+deb7u1
> Severity: normal
> Tags: patch
> 
> Cloning into existing storage volumes is supposedly not supported.
> #706196 marks this as a regression and #745873 as a wishlist item. In
> old-stable it worked, so I feel that calling it a regression is
> correct.

You shouldn't open new reports then.

> 
> When looking at what spit out this error, it seemed to me that the check
> is too simplistic and I can actually clone into existing storage
> volumes, if referenced differently:
> virsh pool-dumpxml vg01
> 
> <pool type='logical'>
>   <name>vg01</name>
>   <uuid>2ae3ae6c-7aa0-f7db-f771-183406d653ee</uuid>
>   <capacity unit='bytes'>560598089728</capacity>
>   <allocation unit='bytes'>157655498752</allocation>
>   <available unit='bytes'>402942590976</available>
>   <source>
>     <device path='/dev/block/104:3'/>
>     <name>vg01</name>
>     <format type='lvm2'/>
>   </source>
>   <target>
>     <path>/dev/vg01</path>
>     <permissions>
>       <mode>0700</mode>
>       <owner>4294967295</owner>
>       <group>4294967295</group>
>     </permissions>
>   </target>
> </pool>
> 
> root at cheetah:/tmp/tmp.oCzq69YIdx# virt-clone -o leap-baseimage -f
> /dev/vg01/review-root -n test
> ERROR    Clone onto existing storage volume is not supported:
> '/dev/vg01/review-root'
> 
> root at cheetah:/tmp/tmp.oCzq69YIdx# virt-clone -o leap-baseimage -f
> /dev/mapper/vg01-review--root  -n test
> Cloning vg01-leap--baseimage
> 
>                         |  10 GB     00:05
> 
> Clone 'test' created successfully.
> 
> I liked that success, but in both cases it was actually writing to the
> same place:
> root at cheetah:/usr/share/pyshared/virtinst# readlink
> /dev/mapper/vg01-review--root
> ../dm-0
> root at cheetah:/usr/share/pyshared/virtinst# readlink /dev/vg01/review-root
> ../dm-0
> Why this happens? The answer is in CloneManager.py:
>     474             if clone_disk.vol_object:
>     475                 # XXX We could do this with vol upload I think
>     476                 raise RuntimeError(
>     477                     _("Clone onto existing storage volume is not "
>     478                       "supported: '%s'") % clone_disk.path)
> 
> For both me and #706196 this is sort of fixed upstream when it are local
> storage pools:
> https://git.fedorahosted.org/cgit/virt-manager.git/tree/virtinst/CloneManager.py?id=v0.10.0
> Virt-inst is now merged in virt-manager. With attached patch (which
> comes from upstream) I'm happy. I don't know if this patch should get
> into backports or the other 2 bugs can be closed because of this and/or
> upstream changes, an explanation of bug-flow would be welcome.

Backports would mean backporting the whole virt-manager 1.0 so we can
only onsider a update via a point update. This would mean we need to
fix it in unstable first which we should do by bringing virt-manager
1.0 into sid (currently only in experimental). I try to find the time
to finally package 1.0 (instead of a git snapshot).

Cheers,
 -- Guido