Re: [PATCH v4 1/1] f2fs: ioctl for removing a range from F2FS

[Matthew Wilcox]

On Wed, May 22, 2019 at 12:05:30PM +0800, sunqiuyang wrote:
> +static int f2fs_ioc_resize_fs(struct file *filp, unsigned long arg)
> +{
> +	struct f2fs_sb_info *sbi = F2FS_I_SB(file_inode(filp));
> +	__u64 block_count;
> +	int ret;
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM;
> +
> +	if (f2fs_readonly(sbi->sb))
> +		return -EROFS;
> +
> +	if (copy_from_user(&block_count, (__u64 __user *)arg, sizeof(__u64)))
> +		return -EFAULT;

You can just call get_user() here.