From 5d2031d99e462c44ab513a3bb0b367185eb670df Mon Sep 17 00:00:00 2001
From: "Joshua M. Boniface" <joshua@boniface.me>
Date: Thu, 4 Jun 2020 10:26:47 -0400
Subject: [PATCH] Prevent a VM migrating to the same node

Prevents a rare edge case where a node can end up "migrating" to itself.
Quick hack to fix this, though like most of the VM management should
probably be rethought/rewritten later.

Fixes #92
---
 node-daemon/pvcnoded/VMInstance.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/node-daemon/pvcnoded/VMInstance.py b/node-daemon/pvcnoded/VMInstance.py
index 11c47977..e5758220 100644
--- a/node-daemon/pvcnoded/VMInstance.py
+++ b/node-daemon/pvcnoded/VMInstance.py
@@ -108,6 +108,7 @@ class VMInstance(object):
         self.domname = zkhandler.readdata(zk_conn, '/domains/{}'.format(domuuid))
         self.state = zkhandler.readdata(self.zk_conn, '/domains/{}/state'.format(self.domuuid))
         self.node = zkhandler.readdata(self.zk_conn, '/domains/{}/node'.format(self.domuuid))
+        self.lastnode = zkhandler.readdata(self.zkconn, '/domains/{}/lastnode'.format(self.domuuid))
         try:
             self.pinpolicy = zkhandler.readdata(self.zk_conn, '/domains/{}/pinpolicy'.format(self.domuuid))
         except:
@@ -147,6 +148,9 @@ class VMInstance(object):
     def getnode(self):
         return self.node
 
+    def getlastnode(self):
+        return self.lastnode
+
     def getdom(self):
         return self.dom
 
@@ -368,6 +372,11 @@ class VMInstance(object):
 
     # Migrate the VM to a target host
     def migrate_vm(self):
+        # Don't try to migrate a node to itself, set back to start
+        if self.node == self.lastnode:
+            zkhandler.writedata(self.zk_conn, { '/domains/{}/state'.format(self.domuuid): 'start' })
+            return
+
         self.inmigrate = True
         self.logger.out('Migrating VM to node "{}"'.format(self.node), state='i', prefix='Domain {}:'.format(self.domuuid))
 
@@ -469,6 +478,7 @@ class VMInstance(object):
         # Update the current values from zookeeper
         self.state = zkhandler.readdata(self.zk_conn, '/domains/{}/state'.format(self.domuuid))
         self.node = zkhandler.readdata(self.zk_conn, '/domains/{}/node'.format(self.domuuid))
+        self.lastnode = zkhandler.readdata(self.zk_conn, '/domains/{}/lastnode'.format(self.domuuid))
 
         # Check the current state of the VM
         try: