Am Mi., 7. Juni 2023 um 00:41 Uhr schrieb Matthew Wilcox (Oracle)
<willy@xxxxxxxxxxxxx>:
> Keep the interface as struct page, but work entirely on the folio
> internally. Removes several PAGE_SIZE assumptions and removes
> some references to page->index and page->mapping.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Tested-by: Bob Peterson <rpeterso@xxxxxxxxxx>
> Reviewed-by: Bob Peterson <rpeterso@xxxxxxxxxx>
> ---
> fs/buffer.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 4d518df50fab..d8c2c000676b 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -2678,33 +2678,31 @@ int block_write_full_page(struct page *page, get_block_t *get_block,
> struct writeback_control *wbc)
> {
> struct folio *folio = page_folio(page);
> - struct inode * const inode = page->mapping->host;
> + struct inode * const inode = folio->mapping->host;
> loff_t i_size = i_size_read(inode);
> - const pgoff_t end_index = i_size >> PAGE_SHIFT;
> - unsigned offset;
>
> - /* Is the page fully inside i_size? */
> - if (page->index < end_index)
> + /* Is the folio fully inside i_size? */
> + if (folio_pos(folio) + folio_size(folio) <= i_size)
> return __block_write_full_folio(inode, folio, get_block, wbc,
> end_buffer_async_write);
>
> - /* Is the page fully outside i_size? (truncate in progress) */
> - offset = i_size & (PAGE_SIZE-1);
> - if (page->index >= end_index+1 || !offset) {
> + /* Is the folio fully outside i_size? (truncate in progress) */
> + if (folio_pos(folio) > i_size) {
The folio is also fully outside i_size if folio_pos(folio) == i_size.
> folio_unlock(folio);
> return 0; /* don't care */
> }
>
> /*
> - * The page straddles i_size. It must be zeroed out on each and every
> + * The folio straddles i_size. It must be zeroed out on each and every
> * writepage invocation because it may be mmapped. "A file is mapped
> * in multiples of the page size. For a file that is not a multiple of
> - * the page size, the remaining memory is zeroed when mapped, and
> + * the page size, the remaining memory is zeroed when mapped, and
> * writes to that region are not written out to the file."
> */
> - zero_user_segment(page, offset, PAGE_SIZE);
> + folio_zero_segment(folio, offset_in_folio(folio, i_size),
> + folio_size(folio));
> return __block_write_full_folio(inode, folio, get_block, wbc,
> - end_buffer_async_write);
> + end_buffer_async_write);
> }
> EXPORT_SYMBOL(block_write_full_page);
>
> --
> 2.39.2
>
Thanks,
Andreas
