[PATCH 4.8 086/138] dm raid: fix compat_features validation

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Whitcroft <apw@xxxxxxxxxxxxx>

commit 5c33677c87cbe44ae04df69c4a29c1750a9ec4e5 upstream.

In ecbfb9f118bce4 ("dm raid: add raid level takeover support") a new
compatible feature flag was added.  Validation for these compat_features
was added but this only passes for new raid mappings with this feature
flag.  This causes previously created raid mappings to be failed at
import.

Check compat_features for the only valid combination.

Fixes: ecbfb9f118bce4 ("dm raid: add raid level takeover support")
Signed-off-by: Andy Whitcroft <apw@xxxxxxxxxxxxx>
Signed-off-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/md/dm-raid.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -2258,7 +2258,8 @@ static int super_validate(struct raid_se
 	if (!mddev->events && super_init_validation(rs, rdev))
 		return -EINVAL;
 
-	if (le32_to_cpu(sb->compat_features) != FEATURE_FLAG_SUPPORTS_V190) {
+	if (le32_to_cpu(sb->compat_features) &&
+	    le32_to_cpu(sb->compat_features) != FEATURE_FLAG_SUPPORTS_V190) {
 		rs->ti->error = "Unable to assemble array: Unknown flag(s) in compatible feature flags";
 		return -EINVAL;
 	}