Re: [PATCH v4 21/27] mm: clean up error handling in write_one_page

[Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>]

On Tue 09-05-17 11:49:24, Jeff Layton wrote:
> Don't try to check PageError since that's potentially racy and not
> necessarily going to be set after writepage errors out.
> 
> Instead, sample the mapping error early on, and use that value to tell
> us whether we got a writeback error since then.
> 
> Signed-off-by: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>

								Honza

> ---
>  mm/page-writeback.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index de0dbf12e2c1..1643456881b4 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2373,11 +2373,12 @@ int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
>  int write_one_page(struct page *page)
>  {
>  	struct address_space *mapping = page->mapping;
> -	int ret = 0;
> +	int ret = 0, ret2;
>  	struct writeback_control wbc = {
>  		.sync_mode = WB_SYNC_ALL,
>  		.nr_to_write = 1,
>  	};
> +	errseq_t since = filemap_sample_wb_error(mapping);
>  
>  	BUG_ON(!PageLocked(page));
>  
> @@ -2386,16 +2387,14 @@ int write_one_page(struct page *page)
>  	if (clear_page_dirty_for_io(page)) {
>  		get_page(page);
>  		ret = mapping->a_ops->writepage(page, &wbc);
> -		if (ret == 0) {
> +		if (ret == 0)
>  			wait_on_page_writeback(page);
> -			if (PageError(page))
> -				ret = -EIO;
> -		}
>  		put_page(page);
>  	} else {
>  		unlock_page(page);
>  	}
> -	return ret;
> +	ret2 = filemap_check_wb_error(mapping, since);
> +	return ret ? : ret2;
>  }
>  EXPORT_SYMBOL(write_one_page);
>  
> -- 
> 2.9.3
> 
> 
-- 
Jan Kara <jack-IBi9RG/b67k@public.gmane.org>
SUSE Labs, CR