btrfs_find_chunk_map_nolock
map = btrfs_find_chunk_map_nolock(fs_info, next_start, U64_MAX);
chunk_map = btrfs_find_chunk_map_nolock(fs_info, start, 1);
map = btrfs_find_chunk_map_nolock(fs_info, logical, length);
struct btrfs_chunk_map *btrfs_find_chunk_map_nolock(struct btrfs_fs_info *fs_info,