libceph: fix pg_temp updates

Usually, we are adding pg_temp entries or removing them.  Occasionally they
update.  In that case, osdmap_apply_incremental() was failing because the
rbtree entry already exists.

Fix by removing the existing entry before inserting a new one.

Fixes http://tracker.newdream.net/issues/2446

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

net/ceph/osdmap.c

@@ -883,8 +883,12 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 		pglen = ceph_decode_32(p);
 
 		if (pglen) {
-			/* insert */
 			ceph_decode_need(p, end, pglen*sizeof(u32), bad);
+
+			/* removing existing (if any) */
+			(void) __remove_pg_mapping(&map->pg_temp, pgid);
+
+			/* insert */
 			pg = kmalloc(sizeof(*pg) + sizeof(u32)*pglen, GFP_NOFS);
 			if (!pg) {
 				err = -ENOMEM;