Re: [PATCH v5 09/23] cifs: Convert wdata_alloc_and_fillpages() to use filemap_get_folios_tag()

[Vishal Moola <vishal.moola@gmail.com>]

On Wed, Jan 4, 2023 at 1:15 PM Vishal Moola (Oracle)
<vishal.moola@gmail.com> wrote:
>
> This is in preparation for the removal of find_get_pages_range_tag(). Now also
> supports the use of large folios.
>
> Since tofind might be larger than the max number of folios in a
> folio_batch (15), we loop through filling in wdata->pages pulling more
> batches until we either reach tofind pages or run out of folios.
>
> This function may not return all pages in the last found folio before
> tofind pages are reached.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
>  fs/cifs/file.c | 32 +++++++++++++++++++++++++++++---
>  1 file changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 22dfc1f8b4f1..8cdd2f67af24 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2527,14 +2527,40 @@ wdata_alloc_and_fillpages(pgoff_t tofind, struct address_space *mapping,
>                           unsigned int *found_pages)
>  {
>         struct cifs_writedata *wdata;
> -
> +       struct folio_batch fbatch;
> +       unsigned int i, idx, p, nr;
>         wdata = cifs_writedata_alloc((unsigned int)tofind,
>                                      cifs_writev_complete);
>         if (!wdata)
>                 return NULL;
>
> -       *found_pages = find_get_pages_range_tag(mapping, index, end,
> -                               PAGECACHE_TAG_DIRTY, tofind, wdata->pages);
> +       folio_batch_init(&fbatch);
> +       *found_pages = 0;
> +
> +again:
> +       nr = filemap_get_folios_tag(mapping, index, end,
> +                               PAGECACHE_TAG_DIRTY, &fbatch);
> +       if (!nr)
> +               goto out; /* No dirty pages left in the range */
> +
> +       for (i = 0; i < nr; i++) {
> +               struct folio *folio = fbatch.folios[i];
> +
> +               idx = 0;
> +               p = folio_nr_pages(folio);
> +add_more:
> +               wdata->pages[*found_pages] = folio_page(folio, idx);
> +               folio_get(folio);
> +               if (++*found_pages == tofind) {
> +                       folio_batch_release(&fbatch);
> +                       goto out;
> +               }
> +               if (++idx < p)
> +                       goto add_more;
> +       }
> +       folio_batch_release(&fbatch);
> +       goto again;
> +out:
>         return wdata;
>  }
>
> --
> 2.38.1
>

Could someone review this cifs patch, please? This is one of the
2 remaining patches that need to be looked at in the series.