Only send a single CAS GET for meta requests

Signed-off-by: Tim Shaffer <[email protected]>

Author: tshaffe1

dix/req.c

@@ -2017,6 +2017,29 @@ static int dix_spare_target_with_data(struct m0_dix_rec_op         *rec_op,
 				 true);
 }
 
+static void dix_online_unit_choose(struct m0_dix_req    *req,
+				   struct m0_dix_rec_op *rec_op)
+{
+	struct m0_dix_pg_unit *pgu;
+	uint64_t               start_unit;
+	uint64_t               i;
+	uint64_t               j;
+
+	M0_ENTRY();
+	M0_PRE(req->dr_type == DIX_GET);
+	start_unit = req->dr_items[rec_op->dgp_item].dxi_pg_unit;
+	M0_ASSERT(start_unit < dix_rec_op_spare_offset(rec_op));
+	for (i = 0; i < start_unit; i++)
+		rec_op->dgp_units[i].dpu_unavail = true;
+	for (i = start_unit; i < rec_op->dgp_units_nr; i++) {
+		pgu = &rec_op->dgp_units[i];
+		if (!pgu->dpu_is_spare && !pgu->dpu_unavail)
+			break;
+	}
+	for (j = i + 1; j < rec_op->dgp_units_nr; j++)
+		rec_op->dgp_units[j].dpu_unavail = true;
+}
+
 static void dix_pg_unit_pd_assign(struct m0_dix_pg_unit *pgu,
 				  struct m0_pooldev     *pd)
 {
@@ -2173,6 +2196,16 @@ static void dix_rop_units_set(struct m0_dix_req *req)
 	}
 
 	m0_rwlock_read_unlock(&pm->pm_lock);
+
+	/*
+	 * For meta requests,
+	 * only one CAS GET request should be sent for every record.
+	 * Choose the best destination for every record.
+	 */
+	if (req->dr_type == DIX_GET && req->dr_is_meta) {
+		for (i = 0; i < rop->dg_rec_ops_nr; i++)
+			dix_online_unit_choose(req, &rop->dg_rec_ops[i]);
+	}
 }
 
 static bool dix_pg_unit_skip(struct m0_dix_req     *req,