Change in vdsm[ovirt-3.5]: Live Merge: Suspend disk stats collection during pivot

Tuesday, 2 September 2014

Hello Federico Simoncelli, Francesco Romani,

I'd like you to do a code review.  Please visit

    http://gerrit.ovirt.org/32326

to review the following change.

Change subject: Live Merge: Suspend disk stats collection during pivot
......................................................................

Live Merge: Suspend disk stats collection during pivot

When pivoting to the new volume after an active layer merge, there is a
brief period where the vdsm metadata is out of sync.  During this time,
the disk stats collection thread will raise an exception since the drive
cannot be referred to by its old path.  Therefore we disable stats
collection during this short window until the metadata can be
synchronized.

Change-Id: I08689aec4d61871a568a6f92661b560fbf4d0b57
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1109918
Signed-off-by: Adam Litke <alitke(a)redhat.com&gt;
Reviewed-on: http://gerrit.ovirt.org/31367
Reviewed-by: Francesco Romani <fromani(a)redhat.com&gt;
Reviewed-by: Federico Simoncelli <fsimonce(a)redhat.com&gt;
---
M vdsm/virt/vm.py
1 file changed, 19 insertions(+), 3 deletions(-)


  git pull ssh://gerrit.ovirt.org:29418/vdsm refs/changes/26/32326/1

diff --git a/vdsm/virt/vm.py b/vdsm/virt/vm.py
index 8c18fd3..94a6b76 100644
--- a/vdsm/virt/vm.py
+++ b/vdsm/virt/vm.py
@@ -5931,11 +5931,25 @@
                                              self.drive.imageID,
                                              self.drive['volumeID'], newVols)
 
+        # A pivot changes the top volume being used for the VM Disk.  Until
+        # we can correct our metadata following the pivot we should not
+        # attempt to collect disk stats.
+        # TODO: Stop collection only for the live merge disk
+        self.vm.stopDisksStatsCollection()
+
         self.vm.log.info("Requesting pivot to complete active layer commit "
                          "(job %s)", self.jobId)
-        flags = libvirt.VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT
-        if self.vm._dom.blockJobAbort(self.drive.name, flags) != 0:
-            raise RuntimeError("pivot failed")
+        try:
+            flags = libvirt.VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT
+            ret = self.vm._dom.blockJobAbort(self.drive.name, flags)
+        except:
+            self.vm.startDisksStatsCollection()
+            raise
+        else:
+            if ret != 0:
+                self.vm.log.error("Pivot failed for job %s (rc=%i)",
+                                  self.jobId, ret)
+                raise RuntimeError("pivot failed")
         self.vm.log.info("Pivot completed (job %s)", self.jobId)
 
     @utils.traceback()
@@ -5945,6 +5959,8 @@
         self.vm.log.info("Synchronizing volume chain after live merge "
                          "(job %s)", self.jobId)
         self.vm._syncVolumeChain(self.drive)
+        if self.doPivot:
+            self.vm.startDisksStatsCollection()
         self.success = True
         self.vm.log.info("Synchronization completed (job %s)", self.jobId)
 


-- 
To view, visit http://gerrit.ovirt.org/32326
To unsubscribe, visit http://gerrit.ovirt.org/settings

Gerrit-MessageType: newchange
Gerrit-Change-Id: I08689aec4d61871a568a6f92661b560fbf4d0b57
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: ovirt-3.5
Gerrit-Owner: Adam Litke <alitke(a)redhat.com&gt;
Gerrit-Reviewer: Federico Simoncelli <fsimonce(a)redhat.com&gt;
Gerrit-Reviewer: Francesco Romani <fromani(a)redhat.com&gt;

    

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