Am Do., 13. Juli 2023 um 06:04 Uhr schrieb Matthew Wilcox (Oracle)
<willy@xxxxxxxxxxxxx>:
> These are the folio equivalent of memcpy_to_page() and memcpy_from_page().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
> include/linux/highmem.h | 44 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index 68da30625a6c..0280f57d4744 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -439,6 +439,50 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len)
> kunmap_local(addr);
> }
>
> +static inline void memcpy_from_folio(char *to, struct folio *folio,
> + size_t offset, size_t len)
> +{
> + VM_BUG_ON(offset + len > folio_size(folio));
> +
> + do {
> + char *from = kmap_local_folio(folio, offset);
> + size_t chunk = len;
> +
> + if (folio_test_highmem(folio) &&
> + (chunk > (PAGE_SIZE - offset_in_page(offset))))
> + chunk = PAGE_SIZE - offset_in_page(offset);
> + memcpy(to, from, len);
We want memcpy(to, from, chunk) here.
> + kunmap_local(from);
> +
> + from += chunk;
> + offset += chunk;
> + len -= chunk;
> + } while (len > 0);
> +}
> +
> +static inline void memcpy_to_folio(struct folio *folio, size_t offset,
> + const char *from, size_t len)
> +{
> + VM_BUG_ON(offset + len > folio_size(folio));
> +
> + do {
> + char *to = kmap_local_folio(folio, offset);
> + size_t chunk = len;
> +
> + if (folio_test_highmem(folio) &&
> + (chunk > (PAGE_SIZE - offset_in_page(offset))))
> + chunk = PAGE_SIZE - offset_in_page(offset);
> + memcpy(to, from, len);
And also here.
> + kunmap_local(to);
> +
> + from += chunk;
> + offset += chunk;
> + len -= chunk;
> + } while (len > 0);
> +
> + flush_dcache_folio(folio);
> +}
> +
> /**
> * memcpy_from_file_folio - Copy some bytes from a file folio.
> * @to: The destination buffer.
> --
> 2.39.2
>
Thanks,
Andreas
