libceph: upmap semantic changes

- apply both pg_upmap and pg_upmap_items
- allow bidirectional swap of pg-upmap-items
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>

net/ceph/osdmap.c

@@ -2437,40 +2437,23 @@ static void apply_upmap(struct ceph_osdmap *osdmap,
 		for (i = 0; i < pg->pg_upmap.len; i++)
 			raw->osds[i] = pg->pg_upmap.osds[i];
 		raw->size = pg->pg_upmap.len;
-		return;
+		/* check and apply pg_upmap_items, if any */
 	}
 
 	pg = lookup_pg_mapping(&osdmap->pg_upmap_items, pgid);
 	if (pg) {
-		/*
-		 * Note: this approach does not allow a bidirectional swap,
-		 * e.g., [[1,2],[2,1]] applied to [0,1,2] -> [0,2,1].
-		 */
-		for (i = 0; i < pg->pg_upmap_items.len; i++) {
-			int from = pg->pg_upmap_items.from_to[i][0];
-			int to = pg->pg_upmap_items.from_to[i][1];
-			int pos = -1;
-			bool exists = false;
-
-			/* make sure replacement doesn't already appear */
-			for (j = 0; j < raw->size; j++) {
-				int osd = raw->osds[j];
+		for (i = 0; i < raw->size; i++) {
+			for (j = 0; j < pg->pg_upmap_items.len; j++) {
+				int from = pg->pg_upmap_items.from_to[j][0];
+				int to = pg->pg_upmap_items.from_to[j][1];
 
-				if (osd == to) {
-					exists = true;
-					break;
-				}
-				/* ignore mapping if target is marked out */
-				if (osd == from && pos < 0 &&
-				    !(to != CRUSH_ITEM_NONE &&
+				if (from == raw->osds[i]) {
+					if (!(to != CRUSH_ITEM_NONE &&
 					      to < osdmap->max_osd &&
-				      osdmap->osd_weight[to] == 0)) {
-					pos = j;
-				}
+					      osdmap->osd_weight[to] == 0))
+						raw->osds[i] = to;
+					break;
 				}
-			if (!exists && pos >= 0) {
-				raw->osds[pos] = to;
-				return;
 			}
 		}
 	}