Re: [PATCH] ext4: Fix WARN_ON from ext4_releasepage()

[Zheng Liu <gnehzuil.liu@gmail.com>]

On Thu, Mar 07, 2013 at 03:52:49PM +0100, Jan Kara wrote:
> ext4_releasepage() warns when it is passed a page with PageChecked set.
> However this can correctly happen when invalidate_inode_pages2_range()
> invalidates pages - and we should fail the release in that case. Since
> the page was dirty anyway, it won't be discarded and no harm has
> happened but it's good to be safe. Also remove bogus page_has_buffers()
> check - we are guaranteed page has buffers in this function.
> 
> Reported-by: Zheng Liu <gnehzuil.liu@gmail.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
Thanks for fixing it.  I can confirm that the warning disappears.
Tested-by: Zheng Liu <wenqing.lz@taobao.com>

Regards,
                                                - Zheng
> ---
>  fs/ext4/inode.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 9c4f4b1..34cc72d 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2912,8 +2912,8 @@ static int ext4_releasepage(struct page *page, gfp_t wait)
>  
>  	trace_ext4_releasepage(page);
>  
> -	WARN_ON(PageChecked(page));
> -	if (!page_has_buffers(page))
> +	/* Page has dirty journalled data -> cannot release */
> +	if (PageChecked(page))
>  		return 0;
>  	if (journal)
>  		return jbd2_journal_try_to_free_buffers(journal, page, wait);
> -- 
> 1.7.1
>