From 53bf5384f9b9e37c628f171366959a38c89779ca Mon Sep 17 00:00:00 2001
From: Heinz Mauelshagen <heinzm@redhat.com>
Date: Wed, 13 Dec 2017 17:13:17 +0100
Subject: [PATCH] dm raid: validate current raid sets redundancy
Git-commit: 53bf5384f9b9e37c628f171366959a38c89779ca
Patch-mainline: v4.16-rc1
References: bsc#1093023

Verifying the current raid sets redundancy based on retrieved
superblock content has to use the superblock's raid level (e.g. raid0),
not the constructor requested one (e.g. raid10).

Using the requested raid level of raid10 lead to a "divide error"
on raid0 which defines data copies divided by to be zero.

Also check for bogus data copies.

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/dm-raid.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 764baa9665bb..b82b7095a671 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1007,7 +1007,7 @@ static int validate_raid_redundancy(struct raid_set *rs)
 		    !rs->dev[i].rdev.sb_page)
 			rebuild_cnt++;
 
-	switch (rs->raid_type->level) {
+	switch (rs->md.level) {
 	case 0:
 		break;
 	case 1:
@@ -1022,6 +1022,11 @@ static int validate_raid_redundancy(struct raid_set *rs)
 		break;
 	case 10:
 		copies = raid10_md_layout_to_copies(rs->md.new_layout);
+		if (copies < 2) {
+			DMERR("Bogus raid10 data copies < 2!");
+			return -EINVAL;
+		}
+
 		if (rebuild_cnt < copies)
 			break;
 
-- 
2.16.3