Re: [PATCH 2/5] btrfs: add new ioctl CLEAR_FREE

[Sun YangKai <sunk67188@gmail.com>]

New to lkml, please correct me if I made any mistake :P

> +static int btrfs_ioctl_clear_free(struct file *file, void __user *arg)
> +{
> +	struct btrfs_fs_info *fs_info;
> +	struct btrfs_ioctl_clear_free_args args;
> +	u64 total_bytes;
> +	int ret;
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM;
> +
> +	if (copy_from_user(&args, arg, sizeof(args)))
> +		return -EFAULT;
> +
> +	if (args.type >= BTRFS_NR_CLEAR_OP_TYPES)
> +		return -EOPNOTSUPP;
> +
> +	ret = mnt_want_write_file(file);
> +	if (ret)
> +		return ret;
> +
> +	fs_info = inode_to_fs_info(file_inode(file));
> +	total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
> +	if (args.start > total_bytes) {
> +		ret = -EINVAL;
> +		goto out_drop_write;
> +	}
> +
> +	ret = btrfs_clear_free_space(fs_info, &args);
> +	if (ret < 0)
> +		goto out_drop_write;
> +
> +	if (copy_to_user(arg, &args, sizeof(args)))
> +		ret = -EFAULT;
> +
> +out_drop_write:
> +	mnt_drop_write_file(file);
> +
> +	return 0;
previous stored return value int `ret` is not used here.
> +}