libceph: return primary from ceph_calc_pg_acting()

In preparation for adding support for primary_temp, stop assuming
primaryness: add a primary out parameter to ceph_calc_pg_acting() and
change call sites accordingly.  Primary is now specified separately
from the order of osds in the set.
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>

include/linux/ceph/osdmap.h

@@ -212,7 +212,7 @@ extern int ceph_oloc_oid_to_pg(struct ceph_osdmap *osdmap,
 
 extern int ceph_calc_pg_acting(struct ceph_osdmap *osdmap,
 			       struct ceph_pg pgid,
-			       int *osds);
+			       int *osds, int *primary);
 extern int ceph_calc_pg_primary(struct ceph_osdmap *osdmap,
 				struct ceph_pg pgid);
 

net/ceph/osd_client.c

@@ -1333,7 +1333,7 @@ static int __map_request(struct ceph_osd_client *osdc,
 {
 	struct ceph_pg pgid;
 	int acting[CEPH_PG_MAX_SIZE];
-	int o = -1, num = 0;
+	int num, o;
 	int err;
 	bool was_paused;
 
@@ -1346,11 +1346,9 @@ static int __map_request(struct ceph_osd_client *osdc,
 	}
 	req->r_pgid = pgid;
 
-	err = ceph_calc_pg_acting(osdc->osdmap, pgid, acting);
-	if (err > 0) {
-		o = acting[0];
-		num = err;
-	}
+	num = ceph_calc_pg_acting(osdc->osdmap, pgid, acting, &o);
+	if (num < 0)
+		num = 0;
 
 	was_paused = req->r_paused;
 	req->r_paused = __req_should_be_paused(osdc, req);

net/ceph/osdmap.c

@@ -1651,19 +1651,21 @@ static int apply_temps(struct ceph_osdmap *osdmap,
 /*
  * Calculate acting set for given pgid.
  *
- * Return acting set length, or error.
+ * Return acting set length, or error.  *primary is set to acting
+ * primary osd id, or -1 if acting set is empty or on error.
  */
 int ceph_calc_pg_acting(struct ceph_osdmap *osdmap, struct ceph_pg pgid,
-			int *osds)
+			int *osds, int *primary)
 {
 	struct ceph_pg_pool_info *pool;
 	u32 pps;
 	int len;
-	int primary;
 
 	pool = __lookup_pg_pool(&osdmap->pg_pools, pgid.pool);
-	if (!pool)
-		return 0;
+	if (!pool) {
+		*primary = -1;
+		return -ENOENT;
+	}
 
 	if (pool->flags & CEPH_POOL_FLAG_HASHPSPOOL) {
 		/* hash pool id and seed so that pool PGs do not overlap */
@@ -1684,12 +1686,14 @@ int ceph_calc_pg_acting(struct ceph_osdmap *osdmap, struct ceph_pg pgid,
 	}
 
 	len = pg_to_raw_osds(osdmap, pool, pgid, pps, osds);
-	if (len < 0)
+	if (len < 0) {
+		*primary = -1;
 		return len;
+	}
 
-	len = raw_to_up_osds(osdmap, pool, osds, len, &primary);
+	len = raw_to_up_osds(osdmap, pool, osds, len, primary);
 
-	len = apply_temps(osdmap, pool, pgid, osds, len, &primary);
+	len = apply_temps(osdmap, pool, pgid, osds, len, primary);
 
 	return len;
 }