On Mon, Jun 26, 2023 at 06:35:13PM +0100, Matthew Wilcox (Oracle) wrote:
> Collapse the two nested loops into one. This is needed as a step
> towards turning this into an iterator.
> ---
> mm/page-writeback.c | 94 ++++++++++++++++++++++-----------------------
> 1 file changed, 47 insertions(+), 47 deletions(-)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 54f2972dab45..68f28eeb15ed 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2461,6 +2461,7 @@ int write_cache_pages(struct address_space *mapping,
> void *data)
> {
> int error;
> + int i = 0;
>
> if (wbc->range_cyclic) {
> wbc->index = mapping->writeback_index; /* prev offset */
> @@ -2478,65 +2479,64 @@ int write_cache_pages(struct address_space *mapping,
> folio_batch_init(&wbc->fbatch);
> wbc->err = 0;
>
> + for (;;) {
> + struct folio *folio;
>
> + if (i == wbc->fbatch.nr) {
> + writeback_get_batch(mapping, wbc);
> + i = 0;
> + }
> if (wbc->fbatch.nr == 0)
> break;
> + folio = wbc->fbatch.folios[i++];
Did you consider moving what is currently the "i" local variable
into strut writeback_control as well? Then writeback_get_batch
could return the current folio, and we could hae a much nicer loop
here by moving all of the above into writeback_get_batch:
while ((folio = writeback_get_batch(mapping, wbc))) {
(and yes, writeback_get_batch probably needs a better name with that)
