Change in vdsm[master]: vm: Cleanup waiting for xml update

Thursday, 16 April 2015

Nir Soffer has uploaded a new change for review.

Change subject: vm: Cleanup waiting for xml update
......................................................................

vm: Cleanup waiting for xml update

This patch cleans up a bit the code for waiting until libvirt xml is
updated after pivot was completed.

- Clarify confusing log message claiming that pivot failed after it
  completed successfully
- Cleanup creation of volumes lists using generator expression
- More clear logic for checking current volumes list
- Replace detailed log message and unhelpful exception with detailed
  exception
- Move comment out of the loop to make the loop more clear
- Remove unneeded keys() calls when looking up alias in chains

This code was added as temporary solution until libvirt is fixed, but I
think we would like keep a simplified version of it even after libvirt
is fixed, verifying that the operation was successful.

Change-Id: I9fec5416a62736bad461ddd0b54093d23960b7a6
Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt;
---
M vdsm/virt/vm.py
1 file changed, 27 insertions(+), 24 deletions(-)


  git pull ssh://gerrit.ovirt.org:29418/vdsm refs/changes/38/39938/1

diff --git a/vdsm/virt/vm.py b/vdsm/virt/vm.py
index efadbdb..8ece47b 100644
--- a/vdsm/virt/vm.py
+++ b/vdsm/virt/vm.py
@@ -5100,40 +5100,43 @@
         # synchronized and we may start the vm with a stale volume in the
         # future.  See https://bugzilla.redhat.com/show_bug.cgi?id=1202719 for
         # more details.
-        # TODO: Remove once we depend on a libvirt with this bug fixed.
 
         # We expect libvirt to show that the original leaf has been removed
         # from the active volume chain.
         origVols = sorted([x['volumeID'] for x in self.drive.volumeChain])
-        expectedVols = origVols[:]
-        expectedVols.remove(self.drive.volumeID)
+        expectedVols = [v for v in origVols if v != self.driveVolumeID]
 
         alias = self.drive['alias']
         self.vm.log.info("Waiting for libvirt to update the XML after pivot "
                          "of drive %s completed", alias)
-        while True:
-            # This operation should complete in either one or two iterations of
-            # this loop.  Until libvirt updates the XML there is nothing to do
-            # but wait.  While we wait we continue to tell engine that the job
-            # is ongoing.  If we are still in this loop when the VM is powered
-            # off, the merge will be resolved manually by engine using the
-            # reconcileVolumeChain verb.
-            chains = self.vm._driveGetActualVolumeChain([self.drive])
-            if alias not in chains.keys():
-                raise RuntimeError("Failed to retrieve volume chain for "
-                                   "drive %s.  Pivot failed.", alias)
-            curVols = sorted([entry.uuid for entry in chains[alias]])
 
-            if curVols == origVols:
-                time.sleep(1)
-            elif curVols == expectedVols:
+        # This operation should complete in either one or two iterations of
+        # this loop.  Until libvirt updates the XML there is nothing to do
+        # but wait.  While we wait we continue to tell engine that the job
+        # is ongoing.  If we are still in this loop when the VM is powered
+        # off, the merge will be resolved manually by engine using the
+        # reconcileVolumeChain verb.
+        # TODO: Check once when we depend on a libvirt with this bug fixed.
+
+        while True:
+            chains = self.vm._driveGetActualVolumeChain([self.drive])
+            if alias not in chains:
+                raise RuntimeError("Failed to retrieve volume chain for "
+                                   "drive %s after pivot completed", alias)
+
+            curVols = sorted(entry.uuid for entry in chains[alias])
+
+            if curVols == expectedVols:
                 self.vm.log.info("The XML update has been completed")
-                break
-            else:
-                self.log.error("Bad volume chain found for drive %s. Previous
"
-                               "chain: %s, Expected chain: %s, Actual chain: "
-                               "%s", alias, origVols, expectedVols, curVols)
-                raise RuntimeError("Bad volume chain found")
+                return
+
+            if curVols != origVols:
+                raise RuntimeError(
+                    "Bad volume chain after pivot for drive %s. Previous "
+                    "chain: %s, Expected chain: %s, Actual chain: %s" %
+                    (alias, origVols, expectedVols, curVols))
+
+            time.sleep(1)
 
 
 def _devicesWithAlias(domXML):


-- 
To view, visit https://gerrit.ovirt.org/39938
To unsubscribe, visit https://gerrit.ovirt.org/settings

Gerrit-MessageType: newchange
Gerrit-Change-Id: I9fec5416a62736bad461ddd0b54093d23960b7a6
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Nir Soffer <nsoffer(a)redhat.com&gt;

    

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