Xen: Cleanup orphan volume connections on boot failure

If the boot process fails after the VDI creation but before a VBD is
created then the current cleanup methods will not work as they all rely
on lookups via VBD.

Change-Id: Id0d93ee60f75bf319baf7859b220ca325175128a
Closes-bug: #1329941

3 files changed, 31 insertions, 0 deletions

diff --git a/nova/virt/xenapi/vmops.py b/nova/virt/xenapi/vmops.py
index c7db7ea992..f8b913b6b5 100644
--- a/nova/virt/xenapi/vmops.py
+++ b/nova/virt/xenapi/vmops.py
@@ -341,6 +341,9 @@ class VMOps(object):
                 vdi_refs = [vdi['ref'] for vdi in vdis.values()
                         if not vdi.get('osvol')]
                 vm_utils.safe_destroy_vdis(self._session, vdi_refs)
+                vol_vdi_refs = [vdi['ref'] for vdi in vdis.values()
+                        if vdi.get('osvol')]
+                self._volumeops.safe_cleanup_from_vdis(vol_vdi_refs)
 
             undo_mgr.undo_with(undo_create_disks)
             return vdis
diff --git a/nova/virt/xenapi/volume_utils.py b/nova/virt/xenapi/volume_utils.py
index d1a01d58f2..f1537914be 100644
--- a/nova/virt/xenapi/volume_utils.py
+++ b/nova/virt/xenapi/volume_utils.py
@@ -301,6 +301,17 @@ def find_sr_from_vbd(session, vbd_ref):
     return sr_ref
 
 
+def find_sr_from_vdi(session, vdi_ref):
+    """Find the SR reference from the VDI reference."""
+    try:
+        sr_ref = session.call_xenapi("VDI.get_SR", vdi_ref)
+    except session.XenAPI.Failure as exc:
+        LOG.exception(exc)
+        raise exception.StorageError(
+                reason=_('Unable to find SR from VDI %s') % vdi_ref)
+    return sr_ref
+
+
 def find_vbd_by_number(session, vm_ref, dev_number):
     """Get the VBD reference from the device number."""
     vbd_refs = session.VM.get_VBDs(vm_ref)
diff --git a/nova/virt/xenapi/volumeops.py b/nova/virt/xenapi/volumeops.py
index 5eb28165af..f6b4bde804 100644
--- a/nova/virt/xenapi/volumeops.py
+++ b/nova/virt/xenapi/volumeops.py
@@ -204,3 +204,20 @@ class VolumeOps(object):
                     raise
 
         return bad_devices
+
+    def safe_cleanup_from_vdis(self, vdi_refs):
+        # A helper method to detach volumes that are not associated with an
+        # instance
+
+        for vdi_ref in vdi_refs:
+            try:
+                sr_ref = volume_utils.find_sr_from_vdi(self._session, vdi_ref)
+            except exception.StorageError as exc:
+                LOG.debug(exc.format_message())
+                continue
+            try:
+                # Forget (i.e. disconnect) SR only if not in use
+                volume_utils.purge_sr(self._session, sr_ref)
+            except Exception:
+                LOG.debug('Ignoring error while purging sr: %s' % sr_ref,
+                        exc_info=True)