Remove flush locking functionality

This just seemed like more trouble that it was worth. Flush locks were
originally intended as a way to counteract the weird issues around
flushing that were mostly fixed by the code refactoring, so this will
help test if those issues are truly gone. If not, will look into a
cleaner solution that doesn't result in unchangeable states.

client-cli/pvc.py

@@ -1648,8 +1648,6 @@ def init_cluster(yes):
     transaction.create('/ceph/pools', ''.encode('ascii'))
     transaction.create('/ceph/volumes', ''.encode('ascii'))
     transaction.create('/ceph/snapshots', ''.encode('ascii'))
-    transaction.create('/locks', ''.encode('ascii'))
-    transaction.create('/locks/flush_lock', 'False'.encode('ascii'))
     transaction.commit()
 
     # Close the Zookeeper connection

client-common/node.py

@@ -148,25 +148,7 @@ def flush_node(zk_conn, node, wait):
     if not common.verifyNode(zk_conn, node):
         return False, 'ERROR: No node named "{}" is present in the cluster.'.format(node)
 
-    if zkhandler.readdata(zk_conn, '/locks/flush_lock') == 'True':
-        if not wait:
-            retmsg = 'A lock currently exists; use --wait to wait for it, or try again later.'.format(node)
-            return False, retmsg
-        retmsg = 'A lock currently exists; waiting for it to complete... '
-        lock_wait = True
-    else:
-        retmsg = 'Flushing hypervisor {} of running VMs.'.format(node)
-        lock_wait = False
-        
-    # Wait cannot be triggered from the API
-    if wait:
-        click.echo(retmsg)
-        retmsg = ""
-        if lock_wait:
-            time.sleep(2)
-            while zkhandler.readdata(zk_conn, '/locks/flush_lock') == 'True':
-                time.sleep(2)
-            click.echo('Previous flush completed. Proceeding with flush.')
+    retmsg = 'Flushing hypervisor {} of running VMs.'.format(node)
 
     # Add the new domain to Zookeeper
     zkhandler.writedata(zk_conn, {
@@ -175,9 +157,8 @@ def flush_node(zk_conn, node, wait):
 
     # Wait cannot be triggered from the API
     if wait:
-        time.sleep(2)
-        while zkhandler.readdata(zk_conn, '/locks/flush_lock') == 'True':
-            time.sleep(2)
+        while zkhandler.readdata(zk_conn, '/nodes/{}/domainstate') == 'flush':
+            time.sleep(1)
 
     return True, retmsg
 
@@ -186,26 +167,8 @@ def ready_node(zk_conn, node, wait):
     if not common.verifyNode(zk_conn, node):
         return False, 'ERROR: No node named "{}" is present in the cluster.'.format(node)
 
-    if zkhandler.readdata(zk_conn, '/locks/flush_lock') == 'True':
-        if not wait:
-            retmsg = 'A lock currently exists; use --wait to wait for it, or try again later.'.format(node)
-            return False, retmsg
-        retmsg = 'A lock currently exists; waiting for it to complete... '
-        lock_wait = True
-    else:
-        retmsg = 'Restoring hypervisor {} to active service.'.format(node)
-        lock_wait = False
+    retmsg = 'Restoring hypervisor {} to active service.'.format(node)
         
-    # Wait cannot be triggered from the API
-    if wait:
-        click.echo(retmsg)
-        retmsg = ""
-        if lock_wait:
-            time.sleep(1)
-            while zkhandler.readdata(zk_conn, '/locks/flush_lock') == 'True':
-                time.sleep(1)
-            click.echo('Previous flush completed. Proceeding with unflush.')
-
     # Add the new domain to Zookeeper
     zkhandler.writedata(zk_conn, {
         '/nodes/{}/domainstate'.format(node): 'unflush'
@@ -213,8 +176,7 @@ def ready_node(zk_conn, node, wait):
 
     # Wait cannot be triggered from the API
     if wait:
-        time.sleep(1)
-        while zkhandler.readdata(zk_conn, '/locks/flush_lock') == 'True':
+        while zkhandler.readdata(zk_conn, '/nodes/{}/domainstate') == 'unflush':
             time.sleep(1)
 
     return True, retmsg

node-daemon/pvcd/NodeInstance.py

@@ -343,16 +343,6 @@ class NodeInstance(object):
 
     # Flush all VMs on the host
     def flush(self):
-        # Wait indefinitely for the flush_lock to be freed
-        time.sleep(0.5)
-        while zkhandler.readdata(self.zk_conn, '/locks/flush_lock') == 'True':
-            time.sleep(2)
-
-        # Acquire the flush lock
-        zkhandler.writedata(self.zk_conn, {
-            '/locks/flush_lock': 'True'
-        })
-
         # Begin flush
         self.inflush = True
         self.logger.out('Flushing node "{}" of running VMs'.format(self.name), state='i')
@@ -394,22 +384,7 @@ class NodeInstance(object):
         zkhandler.writedata(self.zk_conn, { '/nodes/{}/domainstate'.format(self.name): 'flushed' })
         self.inflush = False
 
-        # Release the flush lock
-        zkhandler.writedata(self.zk_conn, {
-            '/locks/flush_lock': 'False'
-        })
-
     def unflush(self):
-        # Wait indefinitely for the flush_lock to be freed
-        time.sleep(0.5)
-        while zkhandler.readdata(self.zk_conn, '/locks/flush_lock') == 'True':
-            time.sleep(2)
-
-        # Acquire the flush lock
-        zkhandler.writedata(self.zk_conn, {
-            '/locks/flush_lock': 'True'
-        })
-
         self.inflush = True
         self.logger.out('Restoring node {} to active service.'.format(self.name), state='i')
         fixed_domain_list = self.d_domain.copy()
@@ -436,8 +411,3 @@ class NodeInstance(object):
         zkhandler.writedata(self.zk_conn, { '/nodes/{}/domainstate'.format(self.name): 'ready' })
         self.inflush = False
 
-        # Release the flush lock
-        zkhandler.writedata(self.zk_conn, {
-            '/locks/flush_lock': 'False'
-        })
-