Re: [PATCH v2 1/1] s390/crash: allow multi-segment iterators

[Matthew Wilcox]

On Thu, Jul 07, 2022 at 02:31:44PM +0100, Al Viro wrote:
> > @@ -73,10 +73,9 @@ int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
> >  		}
> >  		offset = src % PAGE_SIZE;
> >  		bytes = min(PAGE_SIZE - offset, count);
> > -		if (copy_to_user(dest, hsa_buf + offset, bytes))
> > +		if (copy_to_iter(hsa_buf + offset, bytes, iter) != bytes)
> >  			return -EFAULT;
> 
> Umm...  Then you want iov_iter_revert() on short copy...

... maybe better to change the calling convention to return the short
write and have the caller do it if they care?