1 files changed, 140 insertions, 98 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 6c1ea61f39d8..1b4b977809a1 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -59,7 +59,7 @@
 
 int isolate_movable_page(struct page *page, isolate_mode_t mode)
 {
-	struct address_space *mapping;
+	const struct movable_operations *mops;
 
 	/*
 	 * Avoid burning cycles with pages that are yet under __free_pages(),
@@ -97,10 +97,10 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	if (!PageMovable(page) || PageIsolated(page))
 		goto out_no_isolated;
 
-	mapping = page_mapping(page);
-	VM_BUG_ON_PAGE(!mapping, page);
+	mops = page_movable_ops(page);
+	VM_BUG_ON_PAGE(!mops, page);
 
-	if (!mapping->a_ops->isolate_page(page, mode))
+	if (!mops->isolate_page(page, mode))
 		goto out_no_isolated;
 
 	/* Driver shouldn't use PG_isolated bit of page->flags */
@@ -120,10 +120,9 @@ out:
 
 static void putback_movable_page(struct page *page)
 {
-	struct address_space *mapping;
+	const struct movable_operations *mops = page_movable_ops(page);
 
-	mapping = page_mapping(page);
-	mapping->a_ops->putback_page(page);
+	mops->putback_page(page);
 	ClearPageIsolated(page);
 }
 
@@ -337,13 +336,18 @@ unlock:
 }
 #endif
 
-static int expected_page_refs(struct address_space *mapping, struct page *page)
+static int folio_expected_refs(struct address_space *mapping,
+		struct folio *folio)
 {
-	int expected_count = 1;
+	int refs = 1;
+	if (!mapping)
+		return refs;
 
-	if (mapping)
-		expected_count += compound_nr(page) + page_has_private(page);
-	return expected_count;
+	refs += folio_nr_pages(folio);
+	if (folio_test_private(folio))
+		refs++;
+
+	return refs;
 }
 
 /*
@@ -360,7 +364,7 @@ int folio_migrate_mapping(struct address_space *mapping,
 	XA_STATE(xas, &mapping->i_pages, folio_index(folio));
 	struct zone *oldzone, *newzone;
 	int dirty;
-	int expected_count = expected_page_refs(mapping, &folio->page) + extra_count;
+	int expected_count = folio_expected_refs(mapping, folio) + extra_count;
 	long nr = folio_nr_pages(folio);
 
 	if (!mapping) {
@@ -470,26 +474,26 @@ EXPORT_SYMBOL(folio_migrate_mapping);
  * of folio_migrate_mapping().
  */
 int migrate_huge_page_move_mapping(struct address_space *mapping,
-				   struct page *newpage, struct page *page)
+				   struct folio *dst, struct folio *src)
 {
-	XA_STATE(xas, &mapping->i_pages, page_index(page));
+	XA_STATE(xas, &mapping->i_pages, folio_index(src));
 	int expected_count;
 
 	xas_lock_irq(&xas);
-	expected_count = 2 + page_has_private(page);
-	if (!page_ref_freeze(page, expected_count)) {
+	expected_count = 2 + folio_has_private(src);
+	if (!folio_ref_freeze(src, expected_count)) {
 		xas_unlock_irq(&xas);
 		return -EAGAIN;
 	}
 
-	newpage->index = page->index;
-	newpage->mapping = page->mapping;
+	dst->index = src->index;
+	dst->mapping = src->mapping;
 
-	get_page(newpage);
+	folio_get(dst);
 
-	xas_store(&xas, newpage);
+	xas_store(&xas, dst);
 
-	page_ref_unfreeze(page, expected_count - 1);
+	folio_ref_unfreeze(src, expected_count - 1);
 
 	xas_unlock_irq(&xas);
 
@@ -589,34 +593,37 @@ EXPORT_SYMBOL(folio_migrate_copy);
  *                    Migration functions
  ***********************************************************/
 
-/*
- * Common logic to directly migrate a single LRU page suitable for
- * pages that do not use PagePrivate/PagePrivate2.
+/**
+ * migrate_folio() - Simple folio migration.
+ * @mapping: The address_space containing the folio.
+ * @dst: The folio to migrate the data to.
+ * @src: The folio containing the current data.
+ * @mode: How to migrate the page.
+ *
+ * Common logic to directly migrate a single LRU folio suitable for
+ * folios that do not use PagePrivate/PagePrivate2.
  *
- * Pages are locked upon entry and exit.
+ * Folios are locked upon entry and exit.
  */
-int migrate_page(struct address_space *mapping,
-		struct page *newpage, struct page *page,
-		enum migrate_mode mode)
+int migrate_folio(struct address_space *mapping, struct folio *dst,
+		struct folio *src, enum migrate_mode mode)
 {
-	struct folio *newfolio = page_folio(newpage);
-	struct folio *folio = page_folio(page);
 	int rc;
 
-	BUG_ON(folio_test_writeback(folio));	/* Writeback must be complete */
+	BUG_ON(folio_test_writeback(src));	/* Writeback must be complete */
 
-	rc = folio_migrate_mapping(mapping, newfolio, folio, 0);
+	rc = folio_migrate_mapping(mapping, dst, src, 0);
 
 	if (rc != MIGRATEPAGE_SUCCESS)
 		return rc;
 
 	if (mode != MIGRATE_SYNC_NO_COPY)
-		folio_migrate_copy(newfolio, folio);
+		folio_migrate_copy(dst, src);
 	else
-		folio_migrate_flags(newfolio, folio);
+		folio_migrate_flags(dst, src);
 	return MIGRATEPAGE_SUCCESS;
 }
-EXPORT_SYMBOL(migrate_page);
+EXPORT_SYMBOL(migrate_folio);
 
 #ifdef CONFIG_BLOCK
 /* Returns true if all buffers are successfully locked */
@@ -657,23 +664,23 @@ static bool buffer_migrate_lock_buffers(struct buffer_head *head,
 	return true;
 }
 
-static int __buffer_migrate_page(struct address_space *mapping,
-		struct page *newpage, struct page *page, enum migrate_mode mode,
+static int __buffer_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode,
 		bool check_refs)
 {
 	struct buffer_head *bh, *head;
 	int rc;
 	int expected_count;
 
-	if (!page_has_buffers(page))
-		return migrate_page(mapping, newpage, page, mode);
+	head = folio_buffers(src);
+	if (!head)
+		return migrate_folio(mapping, dst, src, mode);
 
 	/* Check whether page does not have extra refs before we do more work */
-	expected_count = expected_page_refs(mapping, page);
-	if (page_count(page) != expected_count)
+	expected_count = folio_expected_refs(mapping, src);
+	if (folio_ref_count(src) != expected_count)
 		return -EAGAIN;
 
-	head = page_buffers(page);
 	if (!buffer_migrate_lock_buffers(head, mode))
 		return -EAGAIN;
 
@@ -704,23 +711,22 @@ recheck_buffers:
 		}
 	}
 
-	rc = migrate_page_move_mapping(mapping, newpage, page, 0);
+	rc = folio_migrate_mapping(mapping, dst, src, 0);
 	if (rc != MIGRATEPAGE_SUCCESS)
 		goto unlock_buffers;
 
-	attach_page_private(newpage, detach_page_private(page));
+	folio_attach_private(dst, folio_detach_private(src));
 
 	bh = head;
 	do {
-		set_bh_page(bh, newpage, bh_offset(bh));
+		set_bh_page(bh, &dst->page, bh_offset(bh));
 		bh = bh->b_this_page;
-
 	} while (bh != head);
 
 	if (mode != MIGRATE_SYNC_NO_COPY)
-		migrate_page_copy(newpage, page);
+		folio_migrate_copy(dst, src);
 	else
-		migrate_page_states(newpage, page);
+		folio_migrate_flags(dst, src);
 
 	rc = MIGRATEPAGE_SUCCESS;
 unlock_buffers:
@@ -730,43 +736,79 @@ unlock_buffers:
 	do {
 		unlock_buffer(bh);
 		bh = bh->b_this_page;
-
 	} while (bh != head);
 
 	return rc;
 }
 
-/*
- * Migration function for pages with buffers. This function can only be used
- * if the underlying filesystem guarantees that no other references to "page"
- * exist. For example attached buffer heads are accessed only under page lock.
+/**
+ * buffer_migrate_folio() - Migration function for folios with buffers.
+ * @mapping: The address space containing @src.
+ * @dst: The folio to migrate to.
+ * @src: The folio to migrate from.
+ * @mode: How to migrate the folio.
+ *
+ * This function can only be used if the underlying filesystem guarantees
+ * that no other references to @src exist. For example attached buffer
+ * heads are accessed only under the folio lock.  If your filesystem cannot
+ * provide this guarantee, buffer_migrate_folio_norefs() may be more
+ * appropriate.
+ *
+ * Return: 0 on success or a negative errno on failure.
  */
-int buffer_migrate_page(struct address_space *mapping,
-		struct page *newpage, struct page *page, enum migrate_mode mode)
+int buffer_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
 {
-	return __buffer_migrate_page(mapping, newpage, page, mode, false);
+	return __buffer_migrate_folio(mapping, dst, src, mode, false);
 }
-EXPORT_SYMBOL(buffer_migrate_page);
+EXPORT_SYMBOL(buffer_migrate_folio);
 
-/*
- * Same as above except that this variant is more careful and checks that there
- * are also no buffer head references. This function is the right one for
- * mappings where buffer heads are directly looked up and referenced (such as
- * block device mappings).
+/**
+ * buffer_migrate_folio_norefs() - Migration function for folios with buffers.
+ * @mapping: The address space containing @src.
+ * @dst: The folio to migrate to.
+ * @src: The folio to migrate from.
+ * @mode: How to migrate the folio.
+ *
+ * Like buffer_migrate_folio() except that this variant is more careful
+ * and checks that there are also no buffer head references. This function
+ * is the right one for mappings where buffer heads are directly looked
+ * up and referenced (such as block device mappings).
+ *
+ * Return: 0 on success or a negative errno on failure.
  */
-int buffer_migrate_page_norefs(struct address_space *mapping,
-		struct page *newpage, struct page *page, enum migrate_mode mode)
+int buffer_migrate_folio_norefs(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
 {
-	return __buffer_migrate_page(mapping, newpage, page, mode, true);
+	return __buffer_migrate_folio(mapping, dst, src, mode, true);
 }
 #endif
 
+int filemap_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
+{
+	int ret;
+
+	ret = folio_migrate_mapping(mapping, dst, src, 0);
+	if (ret != MIGRATEPAGE_SUCCESS)
+		return ret;
+
+	if (folio_get_private(src))
+		folio_attach_private(dst, folio_detach_private(src));
+
+	if (mode != MIGRATE_SYNC_NO_COPY)
+		folio_migrate_copy(dst, src);
+	else
+		folio_migrate_flags(dst, src);
+	return MIGRATEPAGE_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(filemap_migrate_folio);
+
 /*
- * Writeback a page to clean the dirty state
+ * Writeback a folio to clean the dirty state
  */
-static int writeout(struct address_space *mapping, struct page *page)
+static int writeout(struct address_space *mapping, struct folio *folio)
 {
-	struct folio *folio = page_folio(page);
 	struct writeback_control wbc = {
 		.sync_mode = WB_SYNC_NONE,
 		.nr_to_write = 1,
@@ -780,25 +822,25 @@ static int writeout(struct address_space *mapping, struct page *page)
 		/* No write method for the address space */
 		return -EINVAL;
 
-	if (!clear_page_dirty_for_io(page))
+	if (!folio_clear_dirty_for_io(folio))
 		/* Someone else already triggered a write */
 		return -EAGAIN;
 
 	/*
-	 * A dirty page may imply that the underlying filesystem has
-	 * the page on some queue. So the page must be clean for
-	 * migration. Writeout may mean we loose the lock and the
-	 * page state is no longer what we checked for earlier.
+	 * A dirty folio may imply that the underlying filesystem has
+	 * the folio on some queue. So the folio must be clean for
+	 * migration. Writeout may mean we lose the lock and the
+	 * folio state is no longer what we checked for earlier.
 	 * At this point we know that the migration attempt cannot
 	 * be successful.
 	 */
 	remove_migration_ptes(folio, folio, false);
 
-	rc = mapping->a_ops->writepage(page, &wbc);
+	rc = mapping->a_ops->writepage(&folio->page, &wbc);
 
 	if (rc != AOP_WRITEPAGE_ACTIVATE)
 		/* unlocked. Relock */
-		lock_page(page);
+		folio_lock(folio);
 
 	return (rc < 0) ? -EIO : -EAGAIN;
 }
@@ -806,11 +848,11 @@ static int writeout(struct address_space *mapping, struct page *page)
 /*
  * Default handling if a filesystem does not provide a migration function.
  */
-static int fallback_migrate_page(struct address_space *mapping,
-	struct page *newpage, struct page *page, enum migrate_mode mode)
+static int fallback_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
 {
-	if (PageDirty(page)) {
-		/* Only writeback pages in full synchronous migration */
+	if (folio_test_dirty(src)) {
+		/* Only writeback folios in full synchronous migration */
 		switch (mode) {
 		case MIGRATE_SYNC:
 		case MIGRATE_SYNC_NO_COPY:
@@ -818,18 +860,18 @@ static int fallback_migrate_page(struct address_space *mapping,
 		default:
 			return -EBUSY;
 		}
-		return writeout(mapping, page);
+		return writeout(mapping, src);
 	}
 
 	/*
 	 * Buffers may be managed in a filesystem specific way.
 	 * We must have no buffers or drop them.
 	 */
-	if (page_has_private(page) &&
-	    !try_to_release_page(page, GFP_KERNEL))
+	if (folio_test_private(src) &&
+	    !filemap_release_folio(src, GFP_KERNEL))
 		return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
 
-	return migrate_page(mapping, newpage, page, mode);
+	return migrate_folio(mapping, dst, src, mode);
 }
 
 /*
@@ -846,32 +888,32 @@ static int fallback_migrate_page(struct address_space *mapping,
 static int move_to_new_folio(struct folio *dst, struct folio *src,
 				enum migrate_mode mode)
 {
-	struct address_space *mapping;
 	int rc = -EAGAIN;
 	bool is_lru = !__PageMovable(&src->page);
 
 	VM_BUG_ON_FOLIO(!folio_test_locked(src), src);
 	VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst);
 
-	mapping = folio_mapping(src);
-
 	if (likely(is_lru)) {
+		struct address_space *mapping = folio_mapping(src);
+
 		if (!mapping)
-			rc = migrate_page(mapping, &dst->page, &src->page, mode);
-		else if (mapping->a_ops->migratepage)
+			rc = migrate_folio(mapping, dst, src, mode);
+		else if (mapping->a_ops->migrate_folio)
 			/*
-			 * Most pages have a mapping and most filesystems
-			 * provide a migratepage callback. Anonymous pages
+			 * Most folios have a mapping and most filesystems
+			 * provide a migrate_folio callback. Anonymous folios
 			 * are part of swap space which also has its own
-			 * migratepage callback. This is the most common path
+			 * migrate_folio callback. This is the most common path
 			 * for page migration.
 			 */
-			rc = mapping->a_ops->migratepage(mapping, &dst->page,
-							&src->page, mode);
+			rc = mapping->a_ops->migrate_folio(mapping, dst, src,
+								mode);
 		else
-			rc = fallback_migrate_page(mapping, &dst->page,
-							&src->page, mode);
+			rc = fallback_migrate_folio(mapping, dst, src, mode);
 	} else {
+		const struct movable_operations *mops;
+
 		/*
 		 * In case of non-lru page, it could be released after
 		 * isolation step. In that case, we shouldn't try migration.
@@ -883,8 +925,8 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
 			goto out;
 		}
 
-		rc = mapping->a_ops->migratepage(mapping, &dst->page,
-						&src->page, mode);
+		mops = page_movable_ops(&src->page);
+		rc = mops->migrate_page(&dst->page, &src->page, mode);
 		WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
 				!folio_test_isolated(src));
 	}