mon/OSDMonitor: make 'osd crush move ...' work on osds

Currently it only allows you to move buckets, which is annoying and much
less useful.  To move an OSD you need to use create-or-move, which is
harder to use.

Fixes: http://tracker.ceph.com/issues/18587
Signed-off-by: Sage Weil <sage@redhat.com>
(cherry picked from commit 4795647)

qa/workunits/mon/crush_ops.sh

@@ -74,11 +74,16 @@ ceph osd crush rm foo
 ceph osd crush rm osd.$o2 host2
 ceph osd crush rm host2
 
+ceph osd crush add-bucket foo host
+ceph osd crush move foo root=default rack=localrack
+
+ceph osd crush create-or-move osd.$o1 1.0 root=default
+ceph osd crush move osd.$o1 host=foo
+ceph osd find osd.$o1 | grep host | grep foo
+
 ceph osd crush rm osd.$o1
 ceph osd crush rm osd.$o2
 
-ceph osd crush add-bucket foo host
-ceph osd crush move foo root=default rack=localrack
 ceph osd crush rm foo
 
 # test reweight

src/mon/OSDMonitor.cc

@@ -5937,7 +5937,11 @@ bool OSDMonitor::prepare_command_impl(MonOpRequestRef op,
       int id = newcrush.get_item_id(name);
 
       if (!newcrush.check_item_loc(g_ceph_context, id, loc, (int *)NULL)) {
-	err = newcrush.move_bucket(g_ceph_context, id, loc);
+	if (id >= 0) {
+	  err = newcrush.create_or_move_item(g_ceph_context, id, 0, name, loc);
+	} else {
+	  err = newcrush.move_bucket(g_ceph_context, id, loc);
+	}
 	if (err >= 0) {
 	  ss << "moved item id " << id << " name '" << name << "' to location " << loc << " in crush map";
 	  pending_inc.crush.clear();