nfs: don't call bdi_unregister

bdi_destroy already does all the work, and if we delay freeing the
anon bdev we can get away with just that single call.

Addintionally remove the call during mount failure, as
deactivate_super_locked will already call ->kill_sb and clean up
the bdi for us.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 31a11b0..6ec4fe2 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -311,7 +311,6 @@
 	.destroy_inode	= nfs_destroy_inode,
 	.write_inode	= nfs_write_inode,
 	.drop_inode	= nfs_drop_inode,
-	.put_super	= nfs_put_super,
 	.statfs		= nfs_statfs,
 	.evict_inode	= nfs_evict_inode,
 	.umount_begin	= nfs_umount_begin,
@@ -2569,7 +2568,7 @@
 		error = nfs_bdi_register(server);
 		if (error) {
 			mntroot = ERR_PTR(error);
-			goto error_splat_bdi;
+			goto error_splat_super;
 		}
 		server->super = s;
 	}
@@ -2601,9 +2600,6 @@
 	dput(mntroot);
 	mntroot = ERR_PTR(error);
 error_splat_super:
-	if (server && !s->s_root)
-		bdi_unregister(&server->backing_dev_info);
-error_splat_bdi:
 	deactivate_locked_super(s);
 	goto out;
 }
@@ -2651,27 +2647,19 @@
 EXPORT_SYMBOL_GPL(nfs_fs_mount);
 
 /*
- * Ensure that we unregister the bdi before kill_anon_super
- * releases the device name
- */
-void nfs_put_super(struct super_block *s)
-{
-	struct nfs_server *server = NFS_SB(s);
-
-	bdi_unregister(&server->backing_dev_info);
-}
-EXPORT_SYMBOL_GPL(nfs_put_super);
-
-/*
  * Destroy an NFS2/3 superblock
  */
 void nfs_kill_super(struct super_block *s)
 {
 	struct nfs_server *server = NFS_SB(s);
+	dev_t dev = s->s_dev;
 
-	kill_anon_super(s);
+	generic_shutdown_super(s);
+
 	nfs_fscache_release_super_cookie(s);
+
 	nfs_free_server(server);
+	free_anon_bdev(dev);
 }
 EXPORT_SYMBOL_GPL(nfs_kill_super);