diff --git a/[refs] b/[refs]
index 9e4719522557..392d8a0a60dd 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 34e04e87fb8b2c62c9e8868f41c8179d0e15f51a
+refs/heads/master: 7ec0547838976d088dfb9cb0adb073e6e8a15aa3
diff --git a/trunk/drivers/md/raid5.c b/trunk/drivers/md/raid5.c
index 3930b3e9aa04..5694eb8941b6 100644
--- a/trunk/drivers/md/raid5.c
+++ b/trunk/drivers/md/raid5.c
@@ -4169,8 +4169,13 @@ raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks)
 
 	if (!sectors)
 		sectors = mddev->dev_sectors;
-	if (!raid_disks)
-		raid_disks = conf->previous_raid_disks;
+	if (!raid_disks) {
+		/* size is defined by the smallest of previous and new size */
+		if (conf->raid_disks < conf->previous_raid_disks)
+			raid_disks = conf->raid_disks;
+		else
+			raid_disks = conf->previous_raid_disks;
+	}
 
 	sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
 	return sectors * (raid_disks - conf->max_degraded);