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

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

From: Shaohua Li <[email protected]>

[ Upstream commit d595567dc4f0c1d90685ec1e2e296e2cad2643ac ]

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 <[email protected]>
Tested-by: Gioh Kim <[email protected]>
Acked-by: Guoqing Jiang <[email protected]>
Signed-off-by: Shaohua Li <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/md/md.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1766,6 +1766,10 @@ static int super_1_validate(struct mddev
                        } 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)


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