Re: [PATCH v2 6/8] ext4: make the writeback path support large folios

Ojaswin Mujoo
2025-05-20T10:43:24Z

On Mon, May 12, 2025 at 02:33:17PM +0800, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
>
> In mpage_map_and_submit_buffers(), the 'lblk' is now aligned to
> PAGE_SIZE. Convert it to be aligned to folio size. Additionally, modify
> the wbc->nr_to_write update to reduce the number of pages in a single
> folio, ensuring that the entire writeback path can support large folios.
>
Looks good, feel free to add:

Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>

Regards,
ojaswin

> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> ---
> fs/ext4/inode.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 3e962a760d71..29eccdf8315a 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1942,7 +1942,7 @@ static int mpage_submit_folio(struct mpage_da_data *mpd, struct folio *folio)
> len = size & (len - 1);
> err = ext4_bio_write_folio(&mpd->io_submit, folio, len);
> if (!err)
> - mpd->wbc->nr_to_write--;
> + mpd->wbc->nr_to_write -= folio_nr_pages(folio);
>
> return err;
> }
> @@ -2165,7 +2165,6 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
>
> start = mpd->map.m_lblk >> bpp_bits;
> end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
> - lblk = start << bpp_bits;
> pblock = mpd->map.m_pblk;
>
> folio_batch_init(&fbatch);
> @@ -2176,6 +2175,7 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
> for (i = 0; i < nr; i++) {
> struct folio *folio = fbatch.folios[i];
>
> + lblk = folio->index << bpp_bits;
> err = mpage_process_folio(mpd, folio, &lblk, &pblock,
> &map_bh);
> /*
> @@ -2397,7 +2397,7 @@ static int mpage_journal_page_buffers(handle_t *handle,
> size_t len = folio_size(folio);
>
> folio_clear_checked(folio);
> - mpd->wbc->nr_to_write--;
> + mpd->wbc->nr_to_write -= folio_nr_pages(folio);
>
> if (folio_pos(folio) + len > size &&
> !ext4_verity_in_progress(inode))
> --
> 2.46.1
>