btrfs_discard_cancel_work
btrfs_discard_cancel_work(&fs_info->discard_ctl, block_group);
btrfs_discard_cancel_work(&cache->fs_info->discard_ctl,
void btrfs_discard_cancel_work(struct btrfs_discard_ctl *discard_ctl,
btrfs_discard_cancel_work(&fs_info->discard_ctl, bg);