md/plug: optionally use plugger to unplug an array during resync/recovery.

If an array doesn't have a 'queue' then md_do_sync cannot
unplug it.
In that case it will have a 'plugger', so make that available
to the mddev, and use it to unplug the array if needed.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 5be0d6921b9d..57eb864a8249 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -328,6 +328,8 @@ struct mddev_s
         struct list_head                all_mddevs;
 
         struct attribute_group          *to_remove;
+        struct plug_handle              *plug; /* if used by personality */
+
         /* Generic barrier handling.
          * If there is a pending barrier request, all other
          * writes are blocked while the devices are flushed.