--- linux-2.6.16/drivers/md/md.c.orig	2006-06-26 11:28:09.330393250 +0200
+++ linux-2.6.16/drivers/md/md.c	2006-06-26 11:29:11.958307250 +0200
@@ -1022,6 +1022,11 @@
 	if (rdev->sb_size & bmask)
 		rdev-> sb_size = (rdev->sb_size | bmask)+1;
 
+	if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
+		rdev->desc_nr = -1;
+	else
+		rdev->desc_nr = le32_to_cpu(sb->dev_number);
+
 	if (refdev == 0)
 		ret = 1;
 	else {
@@ -1116,7 +1121,6 @@
 
 	if (mddev->level != LEVEL_MULTIPATH) {
 		int role;
-		rdev->desc_nr = le32_to_cpu(sb->dev_number);
 		role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
 		switch(role) {
 		case 0xffff: /* spare */