Re: [PATCH -V3 1/5] swap: Remove get/put_swap_device() in __swap_count()

Chris Li
2023-06-02T05:53:25Z

On Mon, May 29, 2023 at 02:13:51PM +0800, Huang Ying wrote:
> get/put_swap_device() are added to __swap_count() in commit
> eb085574a752 ("mm, swap: fix race between swapoff and some swap
> operations"). Later, in commit 2799e77529c2 ("swap: fix
> do_swap_page() race with swapoff"), get/put_swap_device() are added to
> do_swap_page(). And they enclose the only call site of
> __swap_count(). So, it's safe to remove get/put_swap_device() in
> __swap_count() now.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Tim Chen <tim.c.chen@linux.intel.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Yu Zhao <yuzhao@google.com>
> Cc: Chris Li <chrisl@kernel.org>

Reviewed-By: Chris Li (Google) <chrisl@kernel.org>

Chris

> ---
> mm/swapfile.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 274bbf797480..8419cba9c192 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1432,16 +1432,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
>
> int __swap_count(swp_entry_t entry)
> {
> - struct swap_info_struct *si;
> + struct swap_info_struct *si = swp_swap_info(entry);
> pgoff_t offset = swp_offset(entry);
> - int count = 0;
>
> - si = get_swap_device(entry);
> - if (si) {
> - count = swap_count(si->swap_map[offset]);
> - put_swap_device(si);
> - }
> - return count;
> + return swap_count(si->swap_map[offset]);
> }
>
> /*
> --
> 2.39.2
>