Re: [PATCH 09/12] mm: use SWP_SYNCHRONOUS_IO more intelligently

Jan Kara
2020-09-17T09:07:05Z

On Thu 10-09-20 16:48:29, Christoph Hellwig wrote:
> There is no point in trying to call bdev_read_page if SWP_SYNCHRONOUS_IO
> is not set, as the device won't support it.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> mm/page_io.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/mm/page_io.c b/mm/page_io.c
> index e485a6e8a6cddb..b199b87e0aa92b 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -403,15 +403,17 @@ int swap_readpage(struct page *page, bool synchronous)
> goto out;
> }
>
> - ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
> - if (!ret) {
> - if (trylock_page(page)) {
> - swap_slot_free_notify(page);
> - unlock_page(page);
> - }
> + if (sis->flags & SWP_SYNCHRONOUS_IO) {
> + ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
> + if (!ret) {
> + if (trylock_page(page)) {
> + swap_slot_free_notify(page);
> + unlock_page(page);
> + }
>
> - count_vm_event(PSWPIN);
> - goto out;
> + count_vm_event(PSWPIN);
> + goto out;
> + }
> }
>
> ret = 0;
> --
> 2.28.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR