md/raid10: Remove extras after reshape to smaller number of devices.

When a reshape which reduced the number of devices finishes
we must remove the extra devices.

So ensure  that raid10_remove_disk won't try to keep them, and
have raid10_finish_reshape clear the 'in_sync' flag.  Then
remove_and_add_spares will be able to remove them.

Reported-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index ae2a5a4c6bc5..987db37cb875 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1731,6 +1731,7 @@ static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
         if (!test_bit(Faulty, &rdev->flags) &&
             mddev->recovery_disabled != p->recovery_disabled &&
             (!p->replacement || p->replacement == rdev) &&
+            number < conf->geo.raid_disks &&
             enough(conf, -1)) {
                 err = -EBUSY;
                 goto abort;
@@ -4485,6 +4486,18 @@ static void raid10_finish_reshape(struct mddev *mddev)
                 mddev->resync_max_sectors = size;
                 set_capacity(mddev->gendisk, mddev->array_sectors);
                 revalidate_disk(mddev->gendisk);
+        } else {
+                int d;
+                for (d = conf->geo.raid_disks ;
+                     d < conf->geo.raid_disks - mddev->delta_disks;
+                     d++) {
+                        struct md_rdev *rdev = conf->mirrors[d].rdev;
+                        if (rdev)
+                                clear_bit(In_sync, &rdev->flags);
+                        rdev = conf->mirrors[d].replacement;
+                        if (rdev)
+                                clear_bit(In_sync, &rdev->flags);
+                }
         }
         mddev->layout = mddev->new_layout;
         mddev->chunk_sectors = 1 << conf->geo.chunk_shift;