btrfs_set_buffer_lockdep_class
btrfs_set_buffer_lockdep_class(lockdep_owner, buf, level);
btrfs_set_buffer_lockdep_class(lockdep_owner, eb, level);
btrfs_set_buffer_lockdep_class(btrfs_root_id(root),
void btrfs_set_buffer_lockdep_class(u64 objectid, struct extent_buffer *eb, int level);
btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb), eb,
btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb_rewin),