[PATCH 07/21] swap: Convert add_to_swap() to take a folio

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

The only caller already has a folio available, so this saves a conversion.
Also convert the return type to boolean.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/swap.h |  6 +++---
 mm/swap_state.c      | 47 +++++++++++++++++++++++---------------------
 mm/vmscan.c          |  6 +++---
 3 files changed, 31 insertions(+), 28 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 147a9a173508..f87bb495e482 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -449,7 +449,7 @@ static inline unsigned long total_swapcache_pages(void)
 }
 
 extern void show_swap_cache_info(void);
-extern int add_to_swap(struct page *page);
+bool add_to_swap(struct folio *folio);
 extern void *get_shadow_from_swap_cache(swp_entry_t entry);
 extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
 			gfp_t gfp, void **shadowp);
@@ -630,9 +630,9 @@ struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index)
 	return find_get_page(mapping, index);
 }
 
-static inline int add_to_swap(struct page *page)
+static inline bool add_to_swap(struct folio *folio)
 {
-	return 0;
+	return false;
 }
 
 static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 989ad18f5468..858d8904b06e 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -175,24 +175,26 @@ void __delete_from_swap_cache(struct page *page,
 }
 
 /**
- * add_to_swap - allocate swap space for a page
- * @page: page we want to move to swap
+ * add_to_swap - allocate swap space for a folio
+ * @folio: folio we want to move to swap
  *
- * Allocate swap space for the page and add the page to the
- * swap cache.  Caller needs to hold the page lock. 
+ * Allocate swap space for the folio and add the folio to the
+ * swap cache.
+ *
+ * Context: Caller needs to hold the folio lock.
+ * Return: Whether the folio was added to the swap cache.
  */
-int add_to_swap(struct page *page)
+bool add_to_swap(struct folio *folio)
 {
-	struct folio *folio = page_folio(page);
 	swp_entry_t entry;
 	int err;
 
-	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(!PageUptodate(page), page);
+	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+	VM_BUG_ON_FOLIO(!folio_test_uptodate(folio), folio);
 
 	entry = folio_alloc_swap(folio);
 	if (!entry.val)
-		return 0;
+		return false;
 
 	/*
 	 * XArray node allocations from PF_MEMALLOC contexts could
@@ -205,7 +207,7 @@ int add_to_swap(struct page *page)
 	/*
 	 * Add it to the swap cache.
 	 */
-	err = add_to_swap_cache(page, entry,
+	err = add_to_swap_cache(&folio->page, entry,
 			__GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN, NULL);
 	if (err)
 		/*
@@ -214,22 +216,23 @@ int add_to_swap(struct page *page)
 		 */
 		goto fail;
 	/*
-	 * Normally the page will be dirtied in unmap because its pte should be
-	 * dirty. A special case is MADV_FREE page. The page's pte could have
-	 * dirty bit cleared but the page's SwapBacked bit is still set because
-	 * clearing the dirty bit and SwapBacked bit has no lock protected. For
-	 * such page, unmap will not set dirty bit for it, so page reclaim will
-	 * not write the page out. This can cause data corruption when the page
-	 * is swap in later. Always setting the dirty bit for the page solves
-	 * the problem.
+	 * Normally the folio will be dirtied in unmap because its
+	 * pte should be dirty. A special case is MADV_FREE page. The
+	 * page's pte could have dirty bit cleared but the folio's
+	 * SwapBacked flag is still set because clearing the dirty bit
+	 * and SwapBacked flag has no lock protected. For such folio,
+	 * unmap will not set dirty bit for it, so folio reclaim will
+	 * not write the folio out. This can cause data corruption when
+	 * the folio is swapped in later. Always setting the dirty flag
+	 * for the folio solves the problem.
 	 */
-	set_page_dirty(page);
+	folio_mark_dirty(folio);
 
-	return 1;
+	return true;
 
 fail:
-	put_swap_page(page, entry);
-	return 0;
+	put_swap_page(&folio->page, entry);
+	return false;
 }
 
 /*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 19c1bcd886ef..8f7c32b3d65e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1710,8 +1710,8 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 								page_list))
 						goto activate_locked;
 				}
-				if (!add_to_swap(page)) {
-					if (!PageTransHuge(page))
+				if (!add_to_swap(folio)) {
+					if (!folio_test_large(folio))
 						goto activate_locked_split;
 					/* Fallback to swap normal pages */
 					if (split_folio_to_list(folio,
@@ -1720,7 +1720,7 @@ static unsigned int shrink_page_list(struct list_head *page_list,
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 					count_vm_event(THP_SWPOUT_FALLBACK);
 #endif
-					if (!add_to_swap(page))
+					if (!add_to_swap(folio))
 						goto activate_locked_split;
 				}
 
-- 
2.34.1