mm, swap, get_swap_pages: use entry_size instead of cluster in parameter

yhuang-intel · torvalds · commit 5d5e8f19544a · 2018-08-22T10:52:44.000-07:00
As suggested by Matthew Wilcox, it is better to use "int entry_size" instead of "bool cluster" as parameter to specify whether to operate for huge or normal swap entries. Because this improve the flexibility to support other swap entry size. And Dave Hansen thinks that this improves code readability too. So in this patch, the "bool cluster" parameter of get_swap_pages() is replaced by "int entry_size". And nr_swap_entries() trick is used to reduce the binary size when !CONFIG_TRANSPARENT_HUGE_PAGE. text data bss dec hex filename base 24215 2028 340 26583 67d7 mm/swapfile.o head 24123 2004 340 26467 6763 mm/swapfile.o Link: http://lkml.kernel.org/r/20180720071845.17920-7-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shaohua Li <shli@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/swap.h b/include/linux/swap.h
@@ -447,7 +447,7 @@ 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 get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
 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
@@ -269,8 +269,8 @@ 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, false,
-					   cache->slots);
+		cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE,
+					   cache->slots, 1);
 
 	return cache->nr;
 }
@@ -316,7 +316,7 @@ swp_entry_t get_swap_page(struct page *page)
 
 	if (PageTransHuge(page)) {
 		if (IS_ENABLED(CONFIG_THP_SWAP))
-			get_swap_pages(1, true, &entry);
+			get_swap_pages(1, &entry, HPAGE_PMD_NR);
 		goto out;
 	}
 
@@ -350,7 +350,7 @@ swp_entry_t get_swap_page(struct page *page)
 			goto out;
 	}
 
-	get_swap_pages(1, false, &entry);
+	get_swap_pages(1, &entry, 1);
 out:
 	if (mem_cgroup_try_charge_swap(page, entry)) {
 		put_swap_page(page, entry);
diff --git a/mm/swapfile.c b/mm/swapfile.c
@@ -940,18 +940,18 @@ static unsigned long scan_swap_map(struct swap_info_struct *si,
 
 }
 
-int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[])
+int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size)
 {
-	unsigned long nr_pages = cluster ? SWAPFILE_CLUSTER : 1;
+	unsigned long size = swap_entry_size(entry_size);
 	struct swap_info_struct *si, *next;
 	long avail_pgs;
 	int n_ret = 0;
 	int node;
 
 	/* Only single cluster request supported */
-	WARN_ON_ONCE(n_goal > 1 && cluster);
+	WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER);
 
-	avail_pgs = atomic_long_read(&nr_swap_pages) / nr_pages;
+	avail_pgs = atomic_long_read(&nr_swap_pages) / size;
 	if (avail_pgs <= 0)
 		goto noswap;
 
@@ -961,7 +961,7 @@ int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[])
 	if (n_goal > avail_pgs)
 		n_goal = avail_pgs;
 
-	atomic_long_sub(n_goal * nr_pages, &nr_swap_pages);
+	atomic_long_sub(n_goal * size, &nr_swap_pages);
 
 	spin_lock(&swap_avail_lock);
 
@@ -988,14 +988,14 @@ int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[])
 			spin_unlock(&si->lock);
 			goto nextsi;
 		}
-		if (cluster) {
+		if (size == SWAPFILE_CLUSTER) {
 			if (!(si->flags & SWP_FILE))
 				n_ret = swap_alloc_cluster(si, swp_entries);
 		} else
 			n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE,
 						    n_goal, swp_entries);
 		spin_unlock(&si->lock);
-		if (n_ret || cluster)
+		if (n_ret || size == SWAPFILE_CLUSTER)
 			goto check_out;
 		pr_debug("scan_swap_map of si %d failed to find offset\n",
 			si->type);
@@ -1021,7 +1021,7 @@ int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[])
 
 check_out:
 	if (n_ret < n_goal)
-		atomic_long_add((long)(n_goal - n_ret) * nr_pages,
+		atomic_long_add((long)(n_goal - n_ret) * size,
 				&nr_swap_pages);
 noswap:
 	return n_ret;
