From d595567dc4f0c1d90685ec1e2e296e2cad2643ac Mon Sep 17 00:00:00 2001
From: Shaohua Li <shli@fb.com>
Date: Mon, 1 Oct 2018 18:36:36 -0700
Subject: [PATCH] MD: fix invalid stored role for a disk
Git-commit: d595567dc4f0c1d90685ec1e2e296e2cad2643ac
Patch-mainline: v4.20-rc1
References: bsc#1051510

If we change the number of array's device after device is removed from array,
then add the device back to array, we can see that device is added as active
role instead of spare which we expected.

Please see the below link for details:
https://marc.info/?l=linux-raid&m=153736982015076&w=2

This is caused by that we prefer to use device's previous role which is
recorded by saved_raid_disk, but we should respect the new number of
conf->raid_disks since it could be changed after device is removed.

Reported-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Tested-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Acked-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/md/md.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 63ceabb4e020..a25ebf81b266 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1774,6 +1774,10 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
 			} else
 				set_bit(In_sync, &rdev->flags);
 			rdev->raid_disk = role;
+			if (role >= mddev->raid_disks) {
+				rdev->saved_raid_disk = -1;
+				rdev->raid_disk = -1;
+			}
 			break;
 		}
 		if (sb->devflags & WriteMostly1)
-- 
2.16.4