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

[Kwadronaut-debian]

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.

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.

-- System Information:
Debian Release: 7.5
  APT prefers stable
  APT policy: (990, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-4-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages virtinst depends on:
ii  python             2.7.3-4+deb7u1
ii  python-libvirt     0.9.12.3-1
ii  python-libxml2     2.8.0+dfsg1-7+nmu3
ii  python-support     1.0.15
ii  python-urlgrabber  3.9.1-4

Versions of packages virtinst recommends:
ii  qemu         1.1.2+dfsg-6a+deb7u2
ii  virt-viewer  0.5.3-1

virtinst suggests no packages.

-- no debconf information
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