On Mon 18-12-23 16:35:50, Christoph Hellwig wrote:
> From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
>
> Pull the post-processing of the writepage_t callback into a
> separate function. That means changing writeback_finish() to
> return NULL, and writeback_get_next() to call writeback_finish()
> when we naturally run out of folios.
The part about writeback_finish() does not seem to be true anymore.
Otherwise feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> mm/page-writeback.c | 85 ++++++++++++++++++++++++---------------------
> 1 file changed, 45 insertions(+), 40 deletions(-)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 9d37dd5e58ffb6..0771f19950081f 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2449,8 +2449,10 @@ static struct folio *writeback_get_folio(struct address_space *mapping,
>
> for (;;) {
> folio = writeback_get_next(mapping, wbc);
> - if (!folio)
> + if (!folio) {
> + writeback_finish(mapping, wbc, 0);
> return NULL;
> + }
> folio_lock(folio);
> if (likely(should_writeback_folio(mapping, wbc, folio)))
> break;
> @@ -2477,6 +2479,46 @@ 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 writeback_control *wbc, struct folio *folio, int error)
> +{
> + unsigned long nr = folio_nr_pages(folio);
> +
> + wbc->nr_to_write -= nr;
> +
> + /*
> + * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return value.
> + * Eventually all instances should just unlock the folio themselves and
> + * return 0;
> + */
> + if (error == AOP_WRITEPAGE_ACTIVATE) {
> + folio_unlock(folio);
> + error = 0;
> + }
> +
> + if (error && !wbc->err)
> + wbc->err = error;
> +
> + /*
> + * For integrity sync we have to keep going until we have written all
> + * the folios we tagged for writeback prior to entering the writeback
> + * loop, even if we run past wbc->nr_to_write or encounter errors.
> + * This is because the file system may still have state to clear for
> + * each folio. We'll eventually return the first error encountered.
> + *
> + * For background writeback just push done_index past this folio so that
> + * we can just restart where we left off and media errors won't choke
> + * writeout for the entire file.
> + */
> + if (wbc->sync_mode == WB_SYNC_NONE &&
> + (wbc->err || wbc->nr_to_write <= 0)) {
> + writeback_finish(mapping, wbc, folio->index + nr);
> + return NULL;
> + }
> +
> + return writeback_get_folio(mapping, wbc);
> +}
> +
> /**
> * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
> * @mapping: address space structure to write
> @@ -2517,47 +2559,10 @@ int write_cache_pages(struct address_space *mapping,
>
> for (folio = writeback_iter_init(mapping, wbc);
> folio;
> - folio = writeback_get_folio(mapping, wbc)) {
> - unsigned long nr;
> -
> + folio = writeback_iter_next(mapping, wbc, folio, error))
> error = writepage(folio, wbc, data);
> - nr = folio_nr_pages(folio);
> - wbc->nr_to_write -= nr;
> -
> - /*
> - * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return value.
> - * Eventually all instances should just unlock the folio
> - * themselves and return 0;
> - */
> - if (error == AOP_WRITEPAGE_ACTIVATE) {
> - folio_unlock(folio);
> - error = 0;
> - }
> -
> - if (error && !wbc->err)
> - wbc->err = error;
>
> - /*
> - * For integrity sync we have to keep going until we have
> - * written all the folios we tagged for writeback prior to
> - * entering this loop, even if we run past wbc->nr_to_write or
> - * encounter errors. This is because the file system may still
> - * have state to clear for each folio. We'll eventually return
> - * the first error encountered.
> - *
> - * For background writeback just push done_index past this folio
> - * so that we can just restart where we left off and media
> - * errors won't choke writeout for the entire file.
> - */
> - if (wbc->sync_mode == WB_SYNC_NONE &&
> - (wbc->err || wbc->nr_to_write <= 0)) {
> - writeback_finish(mapping, wbc, folio->index + nr);
> - return error;
> - }
> - }
> -
> - writeback_finish(mapping, wbc, 0);
> - return 0;
> + return wbc->err;
> }
> EXPORT_SYMBOL(write_cache_pages);
>
> --
> 2.39.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
