linux-ext4 - Re: [PATCH 3/3] gfs2: Convert stuffed_readpage() to stuffed_read

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Date:   Thu, 9 Nov 2023 22:52:37 +0100
From:   Andreas Gruenbacher <agruenba@...hat.com>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-ext4@...r.kernel.org, gfs2@...ts.linux.dev,
        linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org,
        "Darrick J . Wong" <djwong@...nel.org>,
        linux-erofs@...ts.ozlabs.org, "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>
Subject: Re: [PATCH 3/3] gfs2: Convert stuffed_readpage() to stuffed_read_folio()

On Tue, Nov 7, 2023 at 10:27 PM Matthew Wilcox (Oracle)
<willy@...radead.org> wrote:
> Use folio_fill_tail() to implement the unstuffing and folio_end_read()
> to simultaneously mark the folio uptodate and unlock it.  Unifies a
> couple of code paths.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
>  fs/gfs2/aops.c | 37 +++++++++++++++++--------------------
>  1 file changed, 17 insertions(+), 20 deletions(-)
>
> diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
> index 9611bfceda4b..ba8742dc91f8 100644
> --- a/fs/gfs2/aops.c
> +++ b/fs/gfs2/aops.c
> @@ -403,18 +403,18 @@ static int gfs2_jdata_writepages(struct address_space *mapping,
>  }
>
>  /**
> - * stuffed_readpage - Fill in a Linux folio with stuffed file data
> + * stuffed_read_folio - Fill in a Linux folio with stuffed file data
>   * @ip: the inode
>   * @folio: the folio
>   *
>   * Returns: errno
>   */
> -static int stuffed_readpage(struct gfs2_inode *ip, struct folio *folio)
> +static int stuffed_read_folio(struct gfs2_inode *ip, struct folio *folio)
>  {
> -       struct buffer_head *dibh;
> -       size_t i_size = i_size_read(&ip->i_inode);
> -       void *data;
> -       int error;
> +       struct buffer_head *dibh = NULL;
> +       size_t dsize = i_size_read(&ip->i_inode);
> +       void *from = NULL;
> +       int error = 0;
>
>         /*
>          * Due to the order of unstuffing files and ->fault(), we can be
> @@ -422,22 +422,20 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct folio *folio)
>          * so we need to supply one here. It doesn't happen often.
>          */
>         if (unlikely(folio->index)) {
> -               folio_zero_range(folio, 0, folio_size(folio));
> -               folio_mark_uptodate(folio);
> -               return 0;
> +               dsize = 0;
> +       } else {
> +               error = gfs2_meta_inode_buffer(ip, &dibh);
> +               if (error)
> +                       goto out;
> +               from = dibh->b_data + sizeof(struct gfs2_dinode);
>         }
>
> -       error = gfs2_meta_inode_buffer(ip, &dibh);
> -       if (error)
> -               return error;
> -
> -       data = dibh->b_data + sizeof(struct gfs2_dinode);
> -       memcpy_to_folio(folio, 0, data, i_size);
> -       folio_zero_range(folio, i_size, folio_size(folio) - i_size);
> +       folio_fill_tail(folio, 0, from, dsize);
>         brelse(dibh);
> -       folio_mark_uptodate(folio);
> +out:
> +       folio_end_read(folio, error == 0);
>
> -       return 0;
> +       return error;
>  }
>
>  /**
> @@ -456,8 +454,7 @@ static int gfs2_read_folio(struct file *file, struct folio *folio)
>             (i_blocksize(inode) == PAGE_SIZE && !folio_buffers(folio))) {
>                 error = iomap_read_folio(folio, &gfs2_iomap_ops);
>         } else if (gfs2_is_stuffed(ip)) {
> -               error = stuffed_readpage(ip, folio);
> -               folio_unlock(folio);
> +               error = stuffed_read_folio(ip, folio);
>         } else {
>                 error = mpage_read_folio(folio, gfs2_block_map);
>         }
> --
> 2.42.0
>

Reviewed-by: Andreas Gruenbacher <agruenba@...hat.com>

Thanks,
Andreas