[Cluster-devel] [PATCH v2 07/14] buffer: Convert block_page_mkwrite() to use a folio

[Andreas Grünbacher]

Am Mi., 7. Juni 2023 um 00:48 Uhr schrieb Matthew Wilcox (Oracle)
<willy at infradead.org>:
> If any page in a folio is dirtied, dirty the entire folio.  Removes a
> number of hidden calls to compound_head() and references to page->mapping
> and page->index.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy at infradead.org>
> ---
>  fs/buffer.c | 27 +++++++++++++--------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index d8c2c000676b..f34ed29b1085 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -2564,38 +2564,37 @@ EXPORT_SYMBOL(block_commit_write);
>  int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
>                          get_block_t get_block)
>  {
> -       struct page *page = vmf->page;
> +       struct folio *folio = page_folio(vmf->page);
>         struct inode *inode = file_inode(vma->vm_file);
>         unsigned long end;
>         loff_t size;
>         int ret;
>
> -       lock_page(page);
> +       folio_lock(folio);
>         size = i_size_read(inode);
> -       if ((page->mapping != inode->i_mapping) ||
> -           (page_offset(page) > size)) {
> +       if ((folio->mapping != inode->i_mapping) ||
> +           (folio_pos(folio) > size)) {

This should probably also be 'folio_pos(folio) >= size', but this was
wrong before this patch already.

>                 /* We overload EFAULT to mean page got truncated */
>                 ret = -EFAULT;
>                 goto out_unlock;
>         }
>
> -       /* page is wholly or partially inside EOF */
> -       if (((page->index + 1) << PAGE_SHIFT) > size)
> -               end = size & ~PAGE_MASK;
> -       else
> -               end = PAGE_SIZE;
> +       end = folio_size(folio);
> +       /* folio is wholly or partially inside EOF */
> +       if (folio_pos(folio) + end > size)
> +               end = size - folio_pos(folio);
>
> -       ret = __block_write_begin(page, 0, end, get_block);
> +       ret = __block_write_begin_int(folio, 0, end, get_block, NULL);
>         if (!ret)
> -               ret = block_commit_write(page, 0, end);
> +               ret = block_commit_write(&folio->page, 0, end);
>
>         if (unlikely(ret < 0))
>                 goto out_unlock;
> -       set_page_dirty(page);
> -       wait_for_stable_page(page);
> +       folio_set_dirty(folio);
> +       folio_wait_stable(folio);
>         return 0;
>  out_unlock:
> -       unlock_page(page);
> +       folio_unlock(folio);
>         return ret;
>  }
>  EXPORT_SYMBOL(block_page_mkwrite);
> --
> 2.39.2
>

Thanks,
Andreas