ctdb-daemon: Move a ZERO_STRUCT() to a better place

It might as well be near where it is used.  Add a comment explaining
it.

Also add/update comments at the top of the RELEASE_IP and TAKEOVER_IP
loops to explain what is happening.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
Autobuild-User(master): Amitay Isaacs <amitay@samba.org>
Autobuild-Date(master): Mon May  5 06:20:39 CEST 2014 on sn-devel-104

diff --git a/ctdb/server/ctdb_takeover.c b/ctdb/server/ctdb_takeover.c
index 14049545dba84808132fc72ca926157278752552..6c21e2bb6ad25b0be157fb8433178172dce33d6a 100644 (file)
--- a/ctdb/server/ctdb_takeover.c
+++ b/ctdb/server/ctdb_takeover.c
@@ -2691,8 +2691,6 @@ int ctdb_takeover_run(struct ctdb_context *ctdb, struct ctdb_node_map *nodemap,
                return -1;
        }
 
-       ZERO_STRUCT(ip);
-
        /* Do the IP reassignment calculations */
        ctdb_takeover_run_core(ctdb, ipflags, &all_ips, force_rebalance_nodes);
 
@@ -2716,6 +2714,14 @@ int ctdb_takeover_run(struct ctdb_context *ctdb, struct ctdb_node_map *nodemap,
        async_data->fail_callback = takeover_run_fail_callback;
        async_data->callback_data = takeover_data;
 
+       ZERO_STRUCT(ip); /* Avoid valgrind warnings for union */
+
+       /* Send a RELEASE_IP to all nodes that should not be hosting
+        * each IP.  For each IP, all but one of these will be
+        * redundant.  However, the redundant ones are used to tell
+        * nodes which node should be hosting the IP so that commands
+        * like "ctdb ip" can display a particular nodes idea of who
+        * is hosting what. */
        for (i=0;i<nodemap->num;i++) {
                /* don't talk to unconnected nodes, but do talk to banned nodes */
                if (nodemap->nodes[i].flags & NODE_FLAGS_DISCONNECTED) {
@@ -2770,7 +2776,10 @@ int ctdb_takeover_run(struct ctdb_context *ctdb, struct ctdb_node_map *nodemap,
        talloc_free(async_data);
 
 
-       /* tell all nodes to get their own IPs */
+       /* For each IP, send a TAKOVER_IP to the node that should be
+        * hosting it.  Many of these will often be redundant (since
+        * the allocation won't have changed) but they can be useful
+        * to recover from inconsistencies. */
        async_data = talloc_zero(tmp_ctx, struct client_async_data);
        CTDB_NO_MEMORY_FATAL(ctdb, async_data);