Merge tag 'folio-6.0' of git://git.infradead.org/users/willy/pagecache

Pull folio updates from Matthew Wilcox:

 - Fix an accounting bug that made NR_FILE_DIRTY grow without limit
   when running xfstests

 - Convert more of mpage to use folios

 - Remove add_to_page_cache() and add_to_page_cache_locked()

 - Convert find_get_pages_range() to filemap_get_folios()

 - Improvements to the read_cache_page() family of functions

 - Remove a few unnecessary checks of PageError

 - Some straightforward filesystem conversions to use folios

 - Split PageMovable users out from address_space_operations into
   their own movable_operations

 - Convert aops->migratepage to aops->migrate_folio

 - Remove nobh support (Christoph Hellwig)

* tag 'folio-6.0' of git://git.infradead.org/users/willy/pagecache: (78 commits)
  fs: remove the NULL get_block case in mpage_writepages
  fs: don't call ->writepage from __mpage_writepage
  fs: remove the nobh helpers
  jfs: stop using the nobh helper
  ext2: remove nobh support
  ntfs3: refactor ntfs_writepages
  mm/folio-compat: Remove migration compatibility functions
  fs: Remove aops->migratepage()
  secretmem: Convert to migrate_folio
  hugetlb: Convert to migrate_folio
  aio: Convert to migrate_folio
  f2fs: Convert to filemap_migrate_folio()
  ubifs: Convert to filemap_migrate_folio()
  btrfs: Convert btrfs_migratepage to migrate_folio
  mm/migrate: Add filemap_migrate_folio()
  mm/migrate: Convert migrate_page() to migrate_folio()
  nfs: Convert to migrate_folio
  btrfs: Convert btree_migratepage to migrate_folio
  mm/migrate: Convert expected_page_refs() to folio_expected_refs()
  mm/migrate: Convert buffer_migrate_page() to buffer_migrate_folio()
  ...

3 files changed, 42 insertions, 34 deletions

diff --git a/Documentation/filesystems/ext2.rst b/Documentation/filesystems/ext2.rst
index 154101cf0e4f..92aae683e16a 100644
--- a/Documentation/filesystems/ext2.rst
+++ b/Documentation/filesystems/ext2.rst
@@ -59,8 +59,6 @@ acl				Enable POSIX Access Control Lists support
 				(requires CONFIG_EXT2_FS_POSIX_ACL).
 noacl				Don't support POSIX ACLs.
 
-nobh				Do not attach buffer_heads to file pagecache.
-
 quota, usrquota			Enable user disk quota support
 				(requires CONFIG_QUOTA).
 
diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index c0fe711f14d3..4bb2627026ec 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -252,9 +252,8 @@ prototypes::
 	bool (*release_folio)(struct folio *, gfp_t);
 	void (*free_folio)(struct folio *);
 	int (*direct_IO)(struct kiocb *, struct iov_iter *iter);
-	bool (*isolate_page) (struct page *, isolate_mode_t);
-	int (*migratepage)(struct address_space *, struct page *, struct page *);
-	void (*putback_page) (struct page *);
+	int (*migrate_folio)(struct address_space *, struct folio *dst,
+			struct folio *src, enum migrate_mode);
 	int (*launder_folio)(struct folio *);
 	bool (*is_partially_uptodate)(struct folio *, size_t from, size_t count);
 	int (*error_remove_page)(struct address_space *, struct page *);
@@ -280,9 +279,7 @@ invalidate_folio:	yes					exclusive
 release_folio:		yes
 free_folio:		yes
 direct_IO:
-isolate_page:		yes
-migratepage:		yes (both)
-putback_page:		yes
+migrate_folio:		yes (both)
 launder_folio:		yes
 is_partially_uptodate:	yes
 error_remove_page:	yes
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index 08069ecd49a6..6cd6953e175b 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -737,12 +737,8 @@ cache in your filesystem.  The following members are defined:
 		bool (*release_folio)(struct folio *, gfp_t);
 		void (*free_folio)(struct folio *);
 		ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
-		/* isolate a page for migration */
-		bool (*isolate_page) (struct page *, isolate_mode_t);
-		/* migrate the contents of a page to the specified target */
-		int (*migratepage) (struct page *, struct page *);
-		/* put migration-failed page back to right list */
-		void (*putback_page) (struct page *);
+		int (*migrate_folio)(struct mapping *, struct folio *dst,
+				struct folio *src, enum migrate_mode);
 		int (*launder_folio) (struct folio *);
 
 		bool (*is_partially_uptodate) (struct folio *, size_t from,
@@ -774,13 +770,38 @@ cache in your filesystem.  The following members are defined:
 	See the file "Locking" for more details.
 
 ``read_folio``
-	called by the VM to read a folio from backing store.  The folio
-	will be locked when read_folio is called, and should be unlocked
-	and marked uptodate once the read completes.  If ->read_folio
-	discovers that it cannot perform the I/O at this time, it can
-        unlock the folio and return AOP_TRUNCATED_PAGE.  In this case,
-	the folio will be looked up again, relocked and if that all succeeds,
-	->read_folio will be called again.
+	Called by the page cache to read a folio from the backing store.
+	The 'file' argument supplies authentication information to network
+	filesystems, and is generally not used by block based filesystems.
+	It may be NULL if the caller does not have an open file (eg if
+	the kernel is performing a read for itself rather than on behalf
+	of a userspace process with an open file).
+
+	If the mapping does not support large folios, the folio will
+	contain a single page.	The folio will be locked when read_folio
+	is called.  If the read completes successfully, the folio should
+	be marked uptodate.  The filesystem should unlock the folio
+	once the read has completed, whether it was successful or not.
+	The filesystem does not need to modify the refcount on the folio;
+	the page cache holds a reference count and that will not be
+	released until the folio is unlocked.
+
+	Filesystems may implement ->read_folio() synchronously.
+	In normal operation, folios are read through the ->readahead()
+	method.  Only if this fails, or if the caller needs to wait for
+	the read to complete will the page cache call ->read_folio().
+	Filesystems should not attempt to perform their own readahead
+	in the ->read_folio() operation.
+
+	If the filesystem cannot perform the read at this time, it can
+	unlock the folio, do whatever action it needs to ensure that the
+	read will succeed in the future and return AOP_TRUNCATED_PAGE.
+	In this case, the caller should look up the folio, lock it,
+	and call ->read_folio again.
+
+	Callers may invoke the ->read_folio() method directly, but using
+	read_mapping_folio() will take care of locking, waiting for the
+	read to complete and handle cases such as AOP_TRUNCATED_PAGE.
 
 ``writepages``
 	called by the VM to write out pages associated with the
@@ -905,20 +926,12 @@ cache in your filesystem.  The following members are defined:
 	data directly between the storage and the application's address
 	space.
 
-``isolate_page``
-	Called by the VM when isolating a movable non-lru page.  If page
-	is successfully isolated, VM marks the page as PG_isolated via
-	__SetPageIsolated.
-
-``migrate_page``
+``migrate_folio``
 	This is used to compact the physical memory usage.  If the VM
-	wants to relocate a page (maybe off a memory card that is
-	signalling imminent failure) it will pass a new page and an old
-	page to this function.  migrate_page should transfer any private
-	data across and update any references that it has to the page.
-
-``putback_page``
-	Called by the VM when isolated page's migration fails.
+	wants to relocate a folio (maybe from a memory device that is
+	signalling imminent failure) it will pass a new folio and an old
+	folio to this function.  migrate_folio should transfer any private
+	data across and update any references that it has to the folio.
 
 ``launder_folio``
 	Called before freeing a folio - it writes back the dirty folio.