On Thu, Jul 06, 2017 at 08:14:01AM -0400, Mimi Zohar wrote:
> This patch defines an ->integrity_read file operation method to read data for
> integrity hash collection.
> -static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
> - size_t count, loff_t *ppos)
> +static ssize_t __efivarfs_file_read(struct file *file, char __user *userbuf,
> + size_t count, loff_t *ppos,
> + struct iov_iter *iter)
> {
> struct efivar_entry *var = file->private_data;
> unsigned long datasize = 0;
> @@ -96,14 +98,32 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
> goto out_free;
>
> memcpy(data, &attributes, sizeof(attributes));
> - size = simple_read_from_buffer(userbuf, count, ppos,
> - data, datasize + sizeof(attributes));
> +
> + if (!iter)
> + size = simple_read_from_buffer(userbuf, count, ppos, data,
> + datasize + sizeof(attributes));
> + else
> + size = copy_to_iter(data, datasize + sizeof(attributes), iter);
Egads... This kind of kludges is too ugly to exist. What the hell for? If you
want to define something that looks like ->read_iter(), bloody make it proper
read_iter. Really working one, that is - without this "our oh-so-special needs
do not include file position" crap.
Seriously, this kind of calling conventions alone is enough for a NAK with
extreme prejudice. Something like
ssize_t simple_read_iter_from_buffer(struct kiocb *iocb, struct iov_iter *to,
const void *from, size_t available)
{
loff_t pos = iocb->ki_pos;
size_t ret;
if (pos < 0)
return -EINVAL;
if (pos >= available)
return 0;
ret = copy_to_iter(to, from + pos, available - pos);
if (!ret && iov_iter_count(to))
return -EFAULT;
iocb->ki_pos = pos + ret;
return ret;
}
EXPORT_SYMBOL(simple_read_iter_from_buffer);
in fs/libfs.c and turn the efivarfs_file_read() into a real ->read_iter() by
replacing simple_read_from_buffer to simple_read_iter_from_buffer (and adjusting
the arguments, of course). All there is to it. Sheesh...
