From b6dd40f59821b4e3e686f3c30f35be4e41a1a84d Mon Sep 17 00:00:00 2001
From: Apollon Oikonomopoulos <apollon@noc.grnet.gr>
Date: Thu, 8 Jul 2010 15:03:58 +0300
Subject: [PATCH] Add _CheckIAllocatorOrNode for common iallocator/node checks

_CheckIAllocatorOrNode will be called by LUs wishing to use an instance
allocator or a target node. It performs sanity checks and will modify the LU's
opcode's iallocator slot to use the cluster-wide allocator if
appropriate.

Signed-off-by: Apollon Oikonomopoulos <apollon@noc.grnet.gr>
Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
---
 lib/cmdlib.py | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/lib/cmdlib.py b/lib/cmdlib.py
index 550d5b941..d29c2b52f 100644
--- a/lib/cmdlib.py
+++ b/lib/cmdlib.py
@@ -1143,6 +1143,38 @@ def _FindFaultyInstanceDisks(cfg, rpc, instance, node_name, prereq):
   return faulty
 
 
+def _CheckIAllocatorOrNode(lu, iallocator_slot, node_slot):
+  """Check the sanity of iallocator and node arguments and use the
+  cluster-wide iallocator if appropriate.
+
+  Check that at most one of (iallocator, node) is specified. If none is
+  specified, then the LU's opcode's iallocator slot is filled with the
+  cluster-wide default iallocator.
+
+  @type iallocator_slot: string
+  @param iallocator_slot: the name of the opcode iallocator slot
+  @type node_slot: string
+  @param node_slot: the name of the opcode target node slot
+
+  """
+  node = getattr(lu.op, node_slot, None)
+  iallocator = getattr(lu.op, iallocator_slot, None)
+
+  if node is not None and iallocator is not None:
+    raise errors.OpPrereqError("Do not specify both, iallocator and node.",
+                               errors.ECODE_INVAL)
+  elif node is None and iallocator is None:
+    default_iallocator = lu.cfg.GetDefaultIAllocator()
+    if default_iallocator:
+      setattr(lu.op, iallocator_slot, default_iallocator)
+    else:
+      raise errors.OpPrereqError("No iallocator or node given and no"
+                                 " cluster-wide default iallocator found."
+                                 " Please specify either an iallocator or a"
+                                 " node, or set a cluster-wide default"
+                                 " iallocator.")
+
+
 class LUPostInitCluster(LogicalUnit):
   """Logical unit for running hooks after cluster initialization.
 
-- 
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