mm: swap: update get_swap_pages() to take folio order

We are about to allow swap storage of any mTHP size.  To prepare for that,
let's change get_swap_pages() to take a folio order parameter instead of
nr_pages.  This makes the interface self-documenting; a power-of-2 number
of pages must be provided.  We will also need the order internally so this
simplifies accessing it.

Link: https://lkml.kernel.org/r/20240408183946.2991168-5-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Gao Xiang <xiang@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index ce35fd4abdf0f74d5ac9f4a98f82333ca8fd8aee..b69b067332473e45c6717b55ecbd0ec0ef093423 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -468,7 +468,7 @@ swp_entry_t folio_alloc_swap(struct folio *folio);
 bool folio_free_swap(struct folio *folio);
 void put_swap_folio(struct folio *folio, swp_entry_t entry);
 extern swp_entry_t get_swap_page_of_type(int);
-extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
+extern int get_swap_pages(int n, swp_entry_t swp_entries[], int order);
 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 extern void swap_shmem_alloc(swp_entry_t);
 extern int swap_duplicate(swp_entry_t);

diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index 53abeaf1371d07c60a371e0b2f1e4182b0a74d11..13ab3b771409c34c3e68d4133e264f10f256eaae 100644 (file)
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -264,7 +264,7 @@ static int refill_swap_slots_cache(struct swap_slots_cache *cache)
        cache->cur = 0;
        if (swap_slot_cache_active)
                cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE,
-                                          cache->slots, 1);
+                                          cache->slots, 0);
 
        return cache->nr;
 }
@@ -311,7 +311,7 @@ swp_entry_t folio_alloc_swap(struct folio *folio)
 
        if (folio_test_large(folio)) {
                if (IS_ENABLED(CONFIG_THP_SWAP))
-                       get_swap_pages(1, &entry, folio_nr_pages(folio));
+                       get_swap_pages(1, &entry, folio_order(folio));
                goto out;
        }
 
@@ -343,7 +343,7 @@ repeat:
                        goto out;
        }
 
-       get_swap_pages(1, &entry, 1);
+       get_swap_pages(1, &entry, 0);
 out:
        if (mem_cgroup_try_charge_swap(folio, entry)) {
                put_swap_folio(folio, entry);

diff --git a/mm/swapfile.c b/mm/swapfile.c
index e3f85547527886a997f43436e4ec4d5e466bf304..d2e3d3cd439f521123a2c40ae6b774687b05473c 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -278,15 +278,15 @@ static void discard_swap_cluster(struct swap_info_struct *si,
 #ifdef CONFIG_THP_SWAP
 #define SWAPFILE_CLUSTER       HPAGE_PMD_NR
 
-#define swap_entry_size(size)  (size)
+#define swap_entry_order(order)        (order)
 #else
 #define SWAPFILE_CLUSTER       256
 
 /*
- * Define swap_entry_size() as constant to let compiler to optimize
+ * Define swap_entry_order() as constant to let compiler to optimize
  * out some code if !CONFIG_THP_SWAP
  */
-#define swap_entry_size(size)  1
+#define swap_entry_order(order)        0
 #endif
 #define LATENCY_LIMIT          256
 
@@ -1042,9 +1042,10 @@ static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx)
        swap_range_free(si, offset, SWAPFILE_CLUSTER);
 }
 
-int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size)
+int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_order)
 {
-       unsigned long size = swap_entry_size(entry_size);
+       int order = swap_entry_order(entry_order);
+       unsigned long size = 1 << order;
        struct swap_info_struct *si, *next;
        long avail_pgs;
        int n_ret = 0;
@@ -1349,7 +1350,7 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry)
        unsigned char *map;
        unsigned int i, free_entries = 0;
        unsigned char val;
-       int size = swap_entry_size(folio_nr_pages(folio));
+       int size = 1 << swap_entry_order(folio_order(folio));
 
        si = _swap_info_get(entry);
        if (!si)