btrfs_start_delalloc_roots
int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, long nr,
ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
btrfs_start_delalloc_roots(fs_info, nr_pages, true);