libceph: generalize ceph_pg_mapping

In preparation for adding support for primary_temp mappings, generalize
struct ceph_pg_mapping so it can hold mappings other than pg_temp.
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>

include/linux/ceph/osdmap.h

@@ -60,8 +60,13 @@ struct ceph_object_id {
 struct ceph_pg_mapping {
 	struct rb_node node;
 	struct ceph_pg pgid;
-	int len;
-	int osds[];
+
+	union {
+		struct {
+			int len;
+			int osds[];
+		} pg_temp;
+	};
 };
 
 struct ceph_osdmap {

net/ceph/debugfs.c

@@ -88,9 +88,9 @@ static int osdmap_show(struct seq_file *s, void *p)
 
 		seq_printf(s, "pg_temp %llu.%x [", pg->pgid.pool,
 			   pg->pgid.seed);
-		for (i = 0; i < pg->len; i++)
+		for (i = 0; i < pg->pg_temp.len; i++)
 			seq_printf(s, "%s%d", (i == 0 ? "" : ","),
-				   pg->osds[i]);
+				   pg->pg_temp.osds[i]);
 		seq_printf(s, "]\n");
 	}
 

net/ceph/osdmap.c

@@ -822,9 +822,9 @@ static int __decode_pg_temp(void **p, void *end, struct ceph_osdmap *map,
 				return -ENOMEM;
 
 			pg->pgid = pgid;
-			pg->len = len;
+			pg->pg_temp.len = len;
 			for (i = 0; i < len; i++)
-				pg->osds[i] = ceph_decode_32(p);
+				pg->pg_temp.osds[i] = ceph_decode_32(p);
 
 			ret = __insert_pg_mapping(pg, &map->pg_temp);
 			if (ret) {
@@ -1281,8 +1281,8 @@ static int *calc_pg_raw(struct ceph_osdmap *osdmap, struct ceph_pg pgid,
 				    pool->pg_num_mask);
 	pg = __lookup_pg_mapping(&osdmap->pg_temp, pgid);
 	if (pg) {
-		*num = pg->len;
-		return pg->osds;
+		*num = pg->pg_temp.len;
+		return pg->pg_temp.osds;
 	}
 
 	/* crush */