3 files changed, 22 insertions, 4 deletions
diff --git a/nova/tests/fake_libvirt_utils.py b/nova/tests/fake_libvirt_utils.py
index 510774939..378515ac0 100644
--- a/nova/tests/fake_libvirt_utils.py
+++ b/nova/tests/fake_libvirt_utils.py
@@ -98,6 +98,10 @@ def file_open(path, mode=None):
     return File(path, mode)
 
 
+def find_disk(virt_dom):
+    return "some/path"
+
+
 def load_file(path):
     if os.path.exists(path):
         with open(path, 'r') as fp:
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 22c64a218..8585c3463 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -823,10 +823,7 @@ class LibvirtDriver(driver.ComputeDriver):
         metadata['container_format'] = base.get('container_format', 'bare')
 
         # Find the disk
-        xml_desc = virt_dom.XMLDesc(0)
-        domain = etree.fromstring(xml_desc)
-        source = domain.find('devices/disk/source')
-        disk_path = source.get('file')
+        disk_path = libvirt_utils.find_disk(virt_dom)
 
         snapshot_name = uuid.uuid4().hex
 
diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py
index 8579abb8a..73e0201df 100644
--- a/nova/virt/libvirt/utils.py
+++ b/nova/virt/libvirt/utils.py
@@ -24,6 +24,7 @@ import hashlib
 import os
 import re
 
+from lxml import etree
 from nova import exception
 from nova import flags
 from nova.openstack.common import cfg
@@ -394,6 +395,22 @@ def file_delete(path):
     return os.unlink(path)
 
 
+def find_disk(virt_dom):
+    """Find root device path for instance
+
+    May be file or device"""
+    xml_desc = virt_dom.XMLDesc(0)
+    domain = etree.fromstring(xml_desc)
+    source = domain.find('devices/disk/source')
+    disk_path = source.get('file') or source.get('dev')
+
+    if not disk_path:
+        raise RuntimeError(_("Can't retrieve root device path "
+                             "from instance libvirt configuration"))
+
+    return disk_path
+
+
 def get_fs_info(path):
     """Get free/used/total space info for a filesystem