[SCSI] libsas: fix sas_find_bcast_phy() in the presence of 'vacant' phys

If an expander reports 'PHY VACANT' for a phy index prior to the one
that generated a BCN libsas fails rediscovery.  Since a vacant phy is
defined as a valid phy index that will never have an attached device
just continue the search.

Cc: <stable@vger.kernel.org>
Signed-off-by: NThomas Jackson <thomas.p.jackson@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/libsas/sas_expander.c

@@ -1718,9 +1718,17 @@ static int sas_find_bcast_phy(struct domain_device *dev, int *phy_id,
 		int phy_change_count = 0;
 
 		res = sas_get_phy_change_count(dev, i, &phy_change_count);
-		if (res)
-			goto out;
-		else if (phy_change_count != ex->ex_phy[i].phy_change_count) {
+		switch (res) {
+		case SMP_RESP_PHY_VACANT:
+		case SMP_RESP_NO_PHY:
+			continue;
+		case SMP_RESP_FUNC_ACC:
+			break;
+		default:
+			return res;
+		}
+
+		if (phy_change_count != ex->ex_phy[i].phy_change_count) {
 			if (update)
 				ex->ex_phy[i].phy_change_count =
 					phy_change_count;
@@ -1728,8 +1736,7 @@ static int sas_find_bcast_phy(struct domain_device *dev, int *phy_id,
 			return 0;
 		}
 	}
-out:
-	return res;
+	return 0;
 }
 
 static int sas_get_ex_change_count(struct domain_device *dev, int *ecc)