mm, THP, swap: unify swap slot free functions to put_swap_page

Now, get_swap_page takes struct page and allocates swap space according
to page size(ie, normal or THP) so it would be more cleaner to introduce
put_swap_page which is a counter function of get_swap_page.  Then, it
calls right swap slot free function depending on page's size.

[ying.huang@intel.com: minor cleanup and fix]
Link: http://lkml.kernel.org/r/20170515112522.32457-3-ying.huang@intel.com
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 10 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 16ff89d058f4..0ad214d7a7ad 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -231,10 +231,7 @@ retry:
         return 1;
 
 fail_free:
-        if (PageTransHuge(page))
-                swapcache_free_cluster(entry);
-        else
-                swapcache_free(entry);
+        put_swap_page(page, entry);
 fail:
         if (PageTransHuge(page) && !split_huge_page_to_list(page, list))
                 goto retry;
@@ -259,11 +256,7 @@ void delete_from_swap_cache(struct page *page)
         __delete_from_swap_cache(page);
         spin_unlock_irq(&address_space->tree_lock);
 
-        if (PageTransHuge(page))
-                swapcache_free_cluster(entry);
-        else
-                swapcache_free(entry);
-
+        put_swap_page(page, entry);
         page_ref_sub(page, hpage_nr_pages(page));
 }
 
@@ -415,7 +408,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
                  * add_to_swap_cache() doesn't return -EEXIST, so we can safely
                  * clear SWAP_HAS_CACHE flag.
                  */
-                swapcache_free(entry);
+                put_swap_page(new_page, entry);
         } while (err != -ENOMEM);
 
         if (new_page)