[PATCH 1/5] filemap: Convert replace_page_cache_page() to replace_page_cache_folio()

["Vishal Moola (Oracle)" <vishal.moola@gmail.com>]

Eliminates 7 calls to compound_head().

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 fs/fuse/dev.c           |  2 +-
 include/linux/pagemap.h |  2 +-
 mm/filemap.c            | 52 ++++++++++++++++++++---------------------
 3 files changed, 27 insertions(+), 29 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index b4a6e0a1b945..26817a2db463 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -837,7 +837,7 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
 	if (WARN_ON(PageMlocked(oldpage)))
 		goto out_fallback_unlock;
 
-	replace_page_cache_page(oldpage, newpage);
+	replace_page_cache_folio(page_folio(oldpage), page_folio(newpage));
 
 	get_page(newpage);
 
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index bbccb4044222..275810697d71 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -1104,7 +1104,7 @@ int filemap_add_folio(struct address_space *mapping, struct folio *folio,
 void filemap_remove_folio(struct folio *folio);
 void delete_from_page_cache(struct page *page);
 void __filemap_remove_folio(struct folio *folio, void *shadow);
-void replace_page_cache_page(struct page *old, struct page *new);
+void replace_page_cache_folio(struct folio *old, struct folio *new);
 void delete_from_page_cache_batch(struct address_space *mapping,
 				  struct folio_batch *fbatch);
 int try_to_release_page(struct page *page, gfp_t gfp);
diff --git a/mm/filemap.c b/mm/filemap.c
index 08341616ae7a..c61dfaa81fee 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -785,56 +785,54 @@ int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)
 EXPORT_SYMBOL(file_write_and_wait_range);
 
 /**
- * replace_page_cache_page - replace a pagecache page with a new one
- * @old:	page to be replaced
- * @new:	page to replace with
- *
- * This function replaces a page in the pagecache with a new one.  On
- * success it acquires the pagecache reference for the new page and
- * drops it for the old page.  Both the old and new pages must be
- * locked.  This function does not add the new page to the LRU, the
+ * replace_page_cache_folio - replace a pagecache folio with a new one
+ * @old:	folio to be replaced
+ * @new:	folio to replace with
+ *
+ * This function replaces a folio in the pagecache with a new one.  On
+ * success it acquires the pagecache reference for the new folio and
+ * drops it for the old folio.  Both the old and new folios must be
+ * locked.  This function does not add the new folio to the LRU, the
  * caller must do that.
  *
  * The remove + add is atomic.  This function cannot fail.
  */
-void replace_page_cache_page(struct page *old, struct page *new)
+void replace_page_cache_folio(struct folio *old, struct folio *new)
 {
-	struct folio *fold = page_folio(old);
-	struct folio *fnew = page_folio(new);
 	struct address_space *mapping = old->mapping;
 	void (*free_folio)(struct folio *) = mapping->a_ops->free_folio;
 	pgoff_t offset = old->index;
 	XA_STATE(xas, &mapping->i_pages, offset);
 
-	VM_BUG_ON_PAGE(!PageLocked(old), old);
-	VM_BUG_ON_PAGE(!PageLocked(new), new);
-	VM_BUG_ON_PAGE(new->mapping, new);
+	VM_BUG_ON_FOLIO(!folio_test_locked(old), old);
+	VM_BUG_ON_FOLIO(!folio_test_locked(new), new);
+	VM_BUG_ON_FOLIO(new->mapping, new);
 
-	get_page(new);
+	folio_get(new);
 	new->mapping = mapping;
 	new->index = offset;
 
-	mem_cgroup_migrate(fold, fnew);
+	mem_cgroup_migrate(old, new);
 
 	xas_lock_irq(&xas);
 	xas_store(&xas, new);
 
 	old->mapping = NULL;
 	/* hugetlb pages do not participate in page cache accounting. */
-	if (!PageHuge(old))
-		__dec_lruvec_page_state(old, NR_FILE_PAGES);
-	if (!PageHuge(new))
-		__inc_lruvec_page_state(new, NR_FILE_PAGES);
-	if (PageSwapBacked(old))
-		__dec_lruvec_page_state(old, NR_SHMEM);
-	if (PageSwapBacked(new))
-		__inc_lruvec_page_state(new, NR_SHMEM);
+	if (!folio_test_hugetlb(old))
+		__lruvec_stat_sub_folio(old, NR_FILE_PAGES);
+	if (!folio_test_hugetlb(new))
+		__lruvec_stat_add_folio(new, NR_FILE_PAGES);
+	if (folio_test_swapbacked(old))
+		__lruvec_stat_sub_folio(old, NR_SHMEM);
+	if (folio_test_swapbacked(new))
+		__lruvec_stat_add_folio(new, NR_SHMEM);
 	xas_unlock_irq(&xas);
 	if (free_folio)
-		free_folio(fold);
-	folio_put(fold);
+		free_folio(old);
+	folio_put(old);
 }
-EXPORT_SYMBOL_GPL(replace_page_cache_page);
+EXPORT_SYMBOL_GPL(replace_page_cache_folio);
 
 noinline int __filemap_add_folio(struct address_space *mapping,
 		struct folio *folio, pgoff_t index, gfp_t gfp, void **shadowp)
-- 
2.38.1