On Fri, 2025-03-14 at 05:05 +0800, Kemeng Shi wrote:
> Replace cluster_swap_free_nr() with swap_entries_put_[map/cache]() to
> remove repeat code and leverage batch-remove for entries with last flag.
>
> Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
> ---
> mm/swapfile.c | 21 ++-------------------
> 1 file changed, 2 insertions(+), 19 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 343b34eb2a81..c27cf09d84a6 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1570,21 +1570,6 @@ static void swap_entries_free(struct swap_info_struct *si,
> __swap_entries_free(si, ci, entry, nr_pages);
> }
>
> -static void cluster_swap_free_nr(struct swap_info_struct *si,
> - unsigned long offset, int nr_pages,
> - unsigned char usage)
> -{
> - struct swap_cluster_info *ci;
> - unsigned long end = offset + nr_pages;
> -
> - ci = lock_cluster(si, offset);
> - do {
> - swap_entry_put_locked(si, ci, swp_entry(si->type, offset),
> - usage);
> - } while (++offset < end);
> - unlock_cluster(ci);
> -}
> -
> /*
> * Caller has made sure that the swap device corresponding to entry
> * is still around or has not been recycled.
> @@ -1601,7 +1586,7 @@ void swap_free_nr(swp_entry_t entry, int nr_pages)
>
> while (nr_pages) {
> nr = min_t(int, nr_pages, SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER);
> - cluster_swap_free_nr(sis, offset, nr, 1);
> + swap_entries_put_map(sis, swp_entry(sis->type, offset), nr);
> offset += nr;
> nr_pages -= nr;
> }
> @@ -3632,9 +3617,7 @@ int swapcache_prepare(swp_entry_t entry, int nr)
>
> void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr)
> {
> - unsigned long offset = swp_offset(entry);
> -
> - cluster_swap_free_nr(si, offset, nr, SWAP_HAS_CACHE);
> + swap_entries_put_cache(si, entry, nr);
swap_entries_put_cache() assumes nr does not cross cluster boundary
as we only lock the cluster associated with the beginning entry.
Current callers to swapcache_clear() like
do_swap_page() and shmem_swapin_folio, call swapcache_clear()
only for pages within a folio so we do fall in a cluster so
we are okay.
Perhaps we should document with a comment that
caller to swapcache_clear() should use the function only for pages in
a folio so the pages don't cross clusters for future users
of swapcache_clear().
Otherwise the patch looks good.
Tim
> }
>
> struct swap_info_struct *swp_swap_info(swp_entry_t entry)
