Re: [PATCH 1/2] ext4: Fixes len calculation in mpage_journal_page_buffers

[Jan Kara <jack@suse.cz>]

On Thu 29-02-24 11:40:13, Ritesh Harjani (IBM) wrote:
> Truncate operation can race with writeback, in which inode->i_size can get
> truncated and therefore size - folio_pos() can be negative. This fixes the
> len calculation. However this path doesn't get easily triggered even
> with data journaling.
> 
> Cc:  <stable@kernel.org> # v6.5
> Fixes: 80be8c5cc925 ("Fixes: ext4: Make mpage_journal_page_buffers use folio")
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/ext4/inode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 537803250ca9..bab9223d94ac 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2334,7 +2334,7 @@ static int mpage_journal_page_buffers(handle_t *handle,
>  
>  	if (folio_pos(folio) + len > size &&
>  	    !ext4_verity_in_progress(inode))
> -		len = size - folio_pos(folio);
> +		len = size & (len - 1);
>  
>  	return ext4_journal_folio_buffers(handle, folio, len);
>  }
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR