ceph: only unregister registered bdi

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index b9cb8cebcdc1..cd81c84e96fc 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -942,7 +942,8 @@ static void ceph_kill_sb(struct super_block *s)
         dout("kill_sb %p\n", s);
         ceph_mdsc_pre_umount(&client->mdsc);
         kill_anon_super(s);    /* will call put_super after sb is r/o */
-        bdi_unregister(&client->backing_dev_info);
+        if (s->s_bdi == &client->backing_dev_info)
+                bdi_unregister(&client->backing_dev_info);
         bdi_destroy(&client->backing_dev_info);
         ceph_destroy_client(client);
 }