On Mon 18-12-23 16:35:51, Christoph Hellwig wrote:
> From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
>
> Wrap up the iterator with a nice bit of syntactic sugar. Now the
> caller doesn't need to know about wbc->err and can just return error,
> not knowing that the iterator took care of storing errors correctly.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Not sure if the trick with 'error' variable isn't a bit too clever for us
;) We'll see how many bugs it will cause in the future... Feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> +#define for_each_writeback_folio(mapping, wbc, folio, error) \
> + for (folio = writeback_iter_init(mapping, wbc); \
> + folio || ((error = wbc->err), false); \
> + folio = writeback_iter_next(mapping, wbc, folio, error))
> +
> typedef int (*writepage_t)(struct folio *folio, struct writeback_control *wbc,
> void *data);
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 0771f19950081f..fbffd30a9cc93f 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2463,7 +2463,7 @@ static struct folio *writeback_get_folio(struct address_space *mapping,
> return folio;
> }
>
> -static struct folio *writeback_iter_init(struct address_space *mapping,
> +struct folio *writeback_iter_init(struct address_space *mapping,
> struct writeback_control *wbc)
> {
> if (wbc->range_cyclic)
> @@ -2479,7 +2479,7 @@ static struct folio *writeback_iter_init(struct address_space *mapping,
> return writeback_get_folio(mapping, wbc);
> }
>
> -static struct folio *writeback_iter_next(struct address_space *mapping,
> +struct folio *writeback_iter_next(struct address_space *mapping,
> struct writeback_control *wbc, struct folio *folio, int error)
> {
> unsigned long nr = folio_nr_pages(folio);
> @@ -2557,9 +2557,7 @@ int write_cache_pages(struct address_space *mapping,
> struct folio *folio;
> int error;
>
> - for (folio = writeback_iter_init(mapping, wbc);
> - folio;
> - folio = writeback_iter_next(mapping, wbc, folio, error))
> + for_each_writeback_folio(mapping, wbc, folio, error)
> error = writepage(folio, wbc, data);
>
> return wbc->err;
> --
> 2.39.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
