Store list of RBD disks in ZK

Store a basic list of RBD disks in Zookeeper for access by the node
subsystem to handle RBD locks. This avoids the need to implement complex
parsing logic inside the fencing configuration (or elsewhere).

Also handle a malformed XML content properly during VM define.

client-common/vm.py

@@ -108,7 +108,10 @@ def getDomainName(zk_conn, domain):
 #
 def define_vm(zk_conn, config_data, target_node, selector):
     # Parse the XML data
+    try:
         parsed_xml = lxml.objectify.fromstring(config_data)
+    except:
+        return False, 'ERROR: Failed to parse XML data.'
     dom_uuid = parsed_xml.uuid.text
     dom_name = parsed_xml.name.text
 
@@ -118,7 +121,14 @@ def define_vm(zk_conn, config_data, target_node, selector):
         # Verify node is valid
         valid_node = common.verifyNode(zk_conn, target_node)
         if not valid_node:
-            return False, 'Specified node "{}" is invalid.'.format(target_node)
+            return False, 'ERROR: Specified node "{}" is invalid.'.format(target_node)
+
+    # Obtain the RBD disk list using the common functions
+    ddisks = common.getDomainDisks(parsed_xml)
+    rbd_list = []
+    for disk in ddisks:
+        if disk['type'] == 'rbd':
+            rbd_list.append(disk['name'])
 
     # Add the new domain to Zookeeper
     zkhandler.writedata(zk_conn, {
@@ -128,6 +138,7 @@ def define_vm(zk_conn, config_data, target_node, selector):
         '/domains/{}/lastnode'.format(dom_uuid): '',
         '/domains/{}/failedreason'.format(dom_uuid): '',
         '/domains/{}/consolelog'.format(dom_uuid): '',
+        '/domains/{}/rbdlist'.format(dom_uuid): ','.join(rbd_list),
         '/domains/{}/xml'.format(dom_uuid): config_data
     })