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.

Cc: Johannes Weiner <han...@cmpxchg.org>
Signed-off-by: Minchan Kim <minc...@kernel.org>
---
 include/linux/swap.h |  4 ++--
 mm/shmem.c           |  2 +-
 mm/swap_state.c      | 13 +++----------
 mm/swapfile.c        |  8 ++++++++
 mm/vmscan.c          |  2 +-
 5 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index b60fea3748f8..8f12f67e869f 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -393,6 +393,7 @@ static inline long get_nr_swap_pages(void)
 
 extern void si_swapinfo(struct sysinfo *);
 extern swp_entry_t get_swap_page(struct page *page);
+extern void put_swap_page(struct page *page, swp_entry_t entry);
 extern swp_entry_t get_swap_page_of_type(int);
 extern int get_swap_pages(int n, bool cluster, swp_entry_t swp_entries[]);
 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
@@ -400,7 +401,6 @@ extern void swap_shmem_alloc(swp_entry_t);
 extern int swap_duplicate(swp_entry_t);
 extern int swapcache_prepare(swp_entry_t);
 extern void swap_free(swp_entry_t);
-extern void swapcache_free(swp_entry_t);
 extern void swapcache_free_entries(swp_entry_t *entries, int n);
 extern int free_swap_and_cache(swp_entry_t);
 extern int swap_type_of(dev_t, sector_t, struct block_device **);
@@ -459,7 +459,7 @@ static inline void swap_free(swp_entry_t swp)
 {
 }
 
-static inline void swapcache_free(swp_entry_t swp)
+static inline void put_swap_page(struct page *page, swp_entry_t swp)
 {
 }
 
diff --git a/mm/shmem.c b/mm/shmem.c
index 29948d7da172..82158edaefdb 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1326,7 +1326,7 @@ static int shmem_writepage(struct page *page, struct 
writeback_control *wbc)
 
        mutex_unlock(&shmem_swaplist_mutex);
 free_swap:
-       swapcache_free(swap);
+       put_swap_page(page, swap);
 redirty:
        set_page_dirty(page);
        if (wbc->for_reclaim)
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 @@ int add_to_swap(struct page *page, struct list_head *list)
        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)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 596306272059..b65e49428090 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1182,6 +1182,14 @@ void swapcache_free_cluster(swp_entry_t entry)
 }
 #endif /* CONFIG_THP_SWAP */
 
+void put_swap_page(struct page *page, swp_entry_t entry)
+{
+       if (!PageTransHuge(page))
+               swapcache_free(entry);
+       else
+               swapcache_free_cluster(entry);
+}
+
 static int swp_entry_cmp(const void *ent1, const void *ent2)
 {
        const swp_entry_t *e1 = ent1, *e2 = ent2;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5ebf468c5429..57268c0c8fcf 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -708,7 +708,7 @@ static int __remove_mapping(struct address_space *mapping, 
struct page *page,
                mem_cgroup_swapout(page, swap);
                __delete_from_swap_cache(page);
                spin_unlock_irqrestore(&mapping->tree_lock, flags);
-               swapcache_free(swap);
+               put_swap_page(page, swap);
        } else {
                void (*freepage)(struct page *);
                void *shadow = NULL;
-- 
2.7.4

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