Btrfs: Add leak debugging for extent_buffer and extent_state

This also fixes one leak around the super block when failing to mount the
FS.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 134b722..1c5e097 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -915,12 +915,14 @@
 	free_extent_buffer(tree_root->node);
 fail_sb_buffer:
 	free_extent_buffer(fs_info->sb_buffer);
+	extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);
 fail_iput:
 	iput(fs_info->btree_inode);
 fail:
 	close_all_devices(fs_info);
 	kfree(extent_root);
 	kfree(tree_root);
+	bdi_destroy(&fs_info->bdi);
 	kfree(fs_info);
 	return ERR_PTR(err);
 }