[for-4.16 PATCH v5 1/4] block: only bdi_unregister() in del_gendisk() if !GENHD_FL_HIDDEN

[Mike Snitzer]

device_add_disk() will only call bdi_register_owner() if
!GENHD_FL_HIDDEN, so it follows that del_gendisk() should only call
bdi_unregister() if !GENHD_FL_HIDDEN.

Found with code inspection.  bdi_unregister() won't do any harm if
bdi_register_owner() wasn't used but best to avoid the unnecessary
call to bdi_unregister().

Fixes: 8ddcd65325 ("block: introduce GENHD_FL_HIDDEN")
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Reviewed-by: Ming Lei <ming....@redhat.com>
Reviewed-by: Hannes Reinecke <h...@suse.com>
---
 block/genhd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index 96a66f671720..00620e01e043 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -725,7 +725,8 @@ void del_gendisk(struct gendisk *disk)
                 * Unregister bdi before releasing device numbers (as they can
                 * get reused and we'd get clashes in sysfs).
                 */
-               bdi_unregister(disk->queue->backing_dev_info);
+               if (!(disk->flags & GENHD_FL_HIDDEN))
+                       bdi_unregister(disk->queue->backing_dev_info);
                blk_unregister_queue(disk);
        } else {
                WARN_ON(1);
-- 
2.15.0