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()
  ...

54 files changed, 350 insertions, 985 deletions

diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index bbb2c210d139..97f50e9fd9eb 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -132,12 +132,6 @@ static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
 		if (IS_ERR(page))
 			return PTR_ERR(page);
 
-		if (PageError(page)) {
-			ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt);
-			put_page(page);
-			return ret;
-		}
-
 		buf = kmap(page);
 		ret = -EINVAL;
 		if (buf[size - 1] == '.')
diff --git a/fs/aio.c b/fs/aio.c
index 3c249b938632..a1911e86859c 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -400,8 +400,8 @@ static const struct file_operations aio_ring_fops = {
 };
 
 #if IS_ENABLED(CONFIG_MIGRATION)
-static int aio_migratepage(struct address_space *mapping, struct page *new,
-			struct page *old, enum migrate_mode mode)
+static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
+			struct folio *src, enum migrate_mode mode)
 {
 	struct kioctx *ctx;
 	unsigned long flags;
@@ -435,10 +435,10 @@ static int aio_migratepage(struct address_space *mapping, struct page *new,
 		goto out;
 	}
 
-	idx = old->index;
+	idx = src->index;
 	if (idx < (pgoff_t)ctx->nr_pages) {
-		/* Make sure the old page hasn't already been changed */
-		if (ctx->ring_pages[idx] != old)
+		/* Make sure the old folio hasn't already been changed */
+		if (ctx->ring_pages[idx] != &src->page)
 			rc = -EAGAIN;
 	} else
 		rc = -EINVAL;
@@ -447,27 +447,27 @@ static int aio_migratepage(struct address_space *mapping, struct page *new,
 		goto out_unlock;
 
 	/* Writeback must be complete */
-	BUG_ON(PageWriteback(old));
-	get_page(new);
+	BUG_ON(folio_test_writeback(src));
+	folio_get(dst);
 
-	rc = migrate_page_move_mapping(mapping, new, old, 1);
+	rc = folio_migrate_mapping(mapping, dst, src, 1);
 	if (rc != MIGRATEPAGE_SUCCESS) {
-		put_page(new);
+		folio_put(dst);
 		goto out_unlock;
 	}
 
 	/* Take completion_lock to prevent other writes to the ring buffer
-	 * while the old page is copied to the new.  This prevents new
+	 * while the old folio is copied to the new.  This prevents new
 	 * events from being lost.
 	 */
 	spin_lock_irqsave(&ctx->completion_lock, flags);
-	migrate_page_copy(new, old);
-	BUG_ON(ctx->ring_pages[idx] != old);
-	ctx->ring_pages[idx] = new;
+	folio_migrate_copy(dst, src);
+	BUG_ON(ctx->ring_pages[idx] != &src->page);
+	ctx->ring_pages[idx] = &dst->page;
 	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 
-	/* The old page is no longer accessible. */
-	put_page(old);
+	/* The old folio is no longer accessible. */
+	folio_put(src);
 
 out_unlock:
 	mutex_unlock(&ctx->ring_lock);
@@ -475,13 +475,13 @@ out:
 	spin_unlock(&mapping->private_lock);
 	return rc;
 }
+#else
+#define aio_migrate_folio NULL
 #endif
 
 static const struct address_space_operations aio_ctx_aops = {
 	.dirty_folio	= noop_dirty_folio,
-#if IS_ENABLED(CONFIG_MIGRATION)
-	.migratepage	= aio_migratepage,
-#endif
+	.migrate_folio	= aio_migrate_folio,
 };
 
 static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c
index be383fa46b12..32749fcee090 100644
--- a/fs/befs/linuxvfs.c
+++ b/fs/befs/linuxvfs.c
@@ -108,8 +108,7 @@ static const struct export_operations befs_export_operations = {
  * passes it the address of befs_get_block, for mapping file
  * positions to disk blocks.
  */
-static int
-befs_read_folio(struct file *file, struct folio *folio)
+static int befs_read_folio(struct file *file, struct folio *folio)
 {
 	return block_read_full_folio(folio, befs_get_block);
 }
@@ -470,13 +469,12 @@ befs_destroy_inodecache(void)
  */
 static int befs_symlink_read_folio(struct file *unused, struct folio *folio)
 {
-	struct page *page = &folio->page;
-	struct inode *inode = page->mapping->host;
+	struct inode *inode = folio->mapping->host;
 	struct super_block *sb = inode->i_sb;
 	struct befs_inode_info *befs_ino = BEFS_I(inode);
 	befs_data_stream *data = &befs_ino->i_data.ds;
 	befs_off_t len = data->size;
-	char *link = page_address(page);
+	char *link = folio_address(folio);
 
 	if (len == 0 || len > PAGE_SIZE) {
 		befs_error(sb, "Long symlink with illegal length");
@@ -489,12 +487,12 @@ static int befs_symlink_read_folio(struct file *unused, struct folio *folio)
 		goto fail;
 	}
 	link[len - 1] = '\0';
-	SetPageUptodate(page);
-	unlock_page(page);
+	folio_mark_uptodate(folio);
+	folio_unlock(folio);
 	return 0;
 fail:
-	SetPageError(page);
-	unlock_page(page);
+	folio_set_error(folio);
+	folio_unlock(folio);
 	return -EIO;
 }
 
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index de440ebf5648..1b23d806a647 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -953,28 +953,28 @@ void btrfs_submit_metadata_bio(struct inode *inode, struct bio *bio, int mirror_
 }
 
 #ifdef CONFIG_MIGRATION
-static int btree_migratepage(struct address_space *mapping,
-			struct page *newpage, struct page *page,
-			enum migrate_mode mode)
+static int btree_migrate_folio(struct address_space *mapping,
+		struct folio *dst, struct folio *src, enum migrate_mode mode)
 {
 	/*
 	 * we can't safely write a btree page from here,
 	 * we haven't done the locking hook
 	 */
-	if (PageDirty(page))
+	if (folio_test_dirty(src))
 		return -EAGAIN;
 	/*
 	 * 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_get_private(src) &&
+	    !filemap_release_folio(src, GFP_KERNEL))
 		return -EAGAIN;
-	return migrate_page(mapping, newpage, page, mode);
+	return migrate_folio(mapping, dst, src, mode);
 }
+#else
+#define btree_migrate_folio NULL
 #endif
 
-
 static int btree_writepages(struct address_space *mapping,
 			    struct writeback_control *wbc)
 {
@@ -1074,10 +1074,8 @@ static const struct address_space_operations btree_aops = {
 	.writepages	= btree_writepages,
 	.release_folio	= btree_release_folio,
 	.invalidate_folio = btree_invalidate_folio,
-#ifdef CONFIG_MIGRATION
-	.migratepage	= btree_migratepage,
-#endif
-	.dirty_folio = btree_dirty_folio,
+	.migrate_folio	= btree_migrate_folio,
+	.dirty_folio	= btree_dirty_folio,
 };
 
 struct extent_buffer *btrfs_find_create_tree_block(
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 57915bf2111f..11a52db506b3 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8268,30 +8268,24 @@ static bool btrfs_release_folio(struct folio *folio, gfp_t gfp_flags)
 }
 
 #ifdef CONFIG_MIGRATION
-static int btrfs_migratepage(struct address_space *mapping,
-			     struct page *newpage, struct page *page,
+static int btrfs_migrate_folio(struct address_space *mapping,
+			     struct folio *dst, struct folio *src,
 			     enum migrate_mode mode)
 {
-	int ret;
+	int ret = filemap_migrate_folio(mapping, dst, src, mode);
 
-	ret = migrate_page_move_mapping(mapping, newpage, page, 0);
 	if (ret != MIGRATEPAGE_SUCCESS)
 		return ret;
 
-	if (page_has_private(page))
-		attach_page_private(newpage, detach_page_private(page));
-
-	if (PageOrdered(page)) {
-		ClearPageOrdered(page);
-		SetPageOrdered(newpage);
+	if (folio_test_ordered(src)) {
+		folio_clear_ordered(src);
+		folio_set_ordered(dst);
 	}
 
-	if (mode != MIGRATE_SYNC_NO_COPY)
-		migrate_page_copy(newpage, page);
-	else
-		migrate_page_states(newpage, page);
 	return MIGRATEPAGE_SUCCESS;
 }
+#else
+#define btrfs_migrate_folio NULL
 #endif
 
 static void btrfs_invalidate_folio(struct folio *folio, size_t offset,
@@ -11436,9 +11430,7 @@ static const struct address_space_operations btrfs_aops = {
 	.direct_IO	= noop_direct_IO,
 	.invalidate_folio = btrfs_invalidate_folio,
 	.release_folio	= btrfs_release_folio,
-#ifdef CONFIG_MIGRATION
-	.migratepage	= btrfs_migratepage,
-#endif
+	.migrate_folio	= btrfs_migrate_folio,
 	.dirty_folio	= filemap_dirty_folio,
 	.error_remove_page = generic_error_remove_page,
 	.swap_activate	= btrfs_swap_activate,
diff --git a/fs/buffer.c b/fs/buffer.c
index 82de136b83bb..55e762a58eb6 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -282,10 +282,10 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
 	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
 
 	/*
-	 * If none of the buffers had errors and they are all
-	 * uptodate then we can set the page uptodate.
+	 * If all of the buffers are uptodate then we can set the page
+	 * uptodate.
 	 */
-	if (page_uptodate && !PageError(page))
+	if (page_uptodate)
 		SetPageUptodate(page);
 	unlock_page(page);
 	return;
@@ -1604,7 +1604,7 @@ void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len)
 {
 	struct inode *bd_inode = bdev->bd_inode;
 	struct address_space *bd_mapping = bd_inode->i_mapping;
-	struct pagevec pvec;
+	struct folio_batch fbatch;
 	pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
 	pgoff_t end;
 	int i, count;
@@ -1612,24 +1612,24 @@ void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len)
 	struct buffer_head *head;
 
 	end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits);
-	pagevec_init(&pvec);
-	while (pagevec_lookup_range(&pvec, bd_mapping, &index, end)) {
-		count = pagevec_count(&pvec);
+	folio_batch_init(&fbatch);
+	while (filemap_get_folios(bd_mapping, &index, end, &fbatch)) {
+		count = folio_batch_count(&fbatch);
 		for (i = 0; i < count; i++) {
-			struct page *page = pvec.pages[i];
+			struct folio *folio = fbatch.folios[i];
 
-			if (!page_has_buffers(page))
+			if (!folio_buffers(folio))
 				continue;
 			/*
-			 * We use page lock instead of bd_mapping->private_lock
+			 * We use folio lock instead of bd_mapping->private_lock
 			 * to pin buffers here since we can afford to sleep and
 			 * it scales better than a global spinlock lock.
 			 */
-			lock_page(page);
-			/* Recheck when the page is locked which pins bhs */
-			if (!page_has_buffers(page))
+			folio_lock(folio);
+			/* Recheck when the folio is locked which pins bhs */
+			head = folio_buffers(folio);
+			if (!head)
 				goto unlock_page;
-			head = page_buffers(page);
 			bh = head;
 			do {
 				if (!buffer_mapped(bh) || (bh->b_blocknr < block))
@@ -1643,9 +1643,9 @@ next:
 				bh = bh->b_this_page;
 			} while (bh != head);
 unlock_page:
-			unlock_page(page);
+			folio_unlock(folio);
 		}
-		pagevec_release(&pvec);
+		folio_batch_release(&fbatch);
 		cond_resched();
 		/* End of range already reached? */
 		if (index > end || !index)
@@ -2259,6 +2259,7 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block)
 	unsigned int blocksize, bbits;
 	int nr, i;
 	int fully_mapped = 1;
+	bool page_error = false;
 
 	VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
 
@@ -2283,8 +2284,10 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block)
 			if (iblock < lblock) {
 				WARN_ON(bh->b_size != blocksize);
 				err = get_block(inode, iblock, bh, 0);
-				if (err)
+				if (err) {
 					folio_set_error(folio);
+					page_error = true;
+				}
 			}
 			if (!buffer_mapped(bh)) {
 				folio_zero_range(folio, i * blocksize,
@@ -2311,7 +2314,7 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block)
 		 * All buffers are uptodate - we can set the folio uptodate
 		 * as well. But not if get_block() returned an error.
 		 */
-		if (!folio_test_error(folio))
+		if (!page_error)
 			folio_mark_uptodate(folio);
 		folio_unlock(folio);
 		return 0;
@@ -2534,330 +2537,6 @@ out_unlock:
 }
 EXPORT_SYMBOL(block_page_mkwrite);
 
-/*
- * nobh_write_begin()'s prereads are special: the buffer_heads are freed
- * immediately, while under the page lock.  So it needs a special end_io
- * handler which does not touch the bh after unlocking it.
- */
-static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
-{
-	__end_buffer_read_notouch(bh, uptodate);
-}
-
-/*
- * Attach the singly-linked list of buffers created by nobh_write_begin, to
- * the page (converting it to circular linked list and taking care of page
- * dirty races).
- */
-static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
-{
-	struct buffer_head *bh;
-
-	BUG_ON(!PageLocked(page));
-
-	spin_lock(&page->mapping->private_lock);
-	bh = head;
-	do {
-		if (PageDirty(page))
-			set_buffer_dirty(bh);
-		if (!bh->b_this_page)
-			bh->b_this_page = head;
-		bh = bh->b_this_page;
-	} while (bh != head);
-	attach_page_private(page, head);
-	spin_unlock(&page->mapping->private_lock);
-}
-
-/*
- * On entry, the page is fully not uptodate.
- * On exit the page is fully uptodate in the areas outside (from,to)
- * The filesystem needs to handle block truncation upon failure.
- */
-int nobh_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
-			struct page **pagep, void **fsdata,
-			get_block_t *get_block)
-{
-	struct inode *inode = mapping->host;
-	const unsigned blkbits = inode->i_blkbits;
-	const unsigned blocksize = 1 << blkbits;
-	struct buffer_head *head, *bh;
-	struct page *page;
-	pgoff_t index;
-	unsigned from, to;
-	unsigned block_in_page;
-	unsigned block_start, block_end;
-	sector_t block_in_file;
-	int nr_reads = 0;
-	int ret = 0;
-	int is_mapped_to_disk = 1;
-
-	index = pos >> PAGE_SHIFT;
-	from = pos & (PAGE_SIZE - 1);
-	to = from + len;
-
-	page = grab_cache_page_write_begin(mapping, index);
-	if (!page)
-		return -ENOMEM;
-	*pagep = page;
-	*fsdata = NULL;
-
-	if (page_has_buffers(page)) {
-		ret = __block_write_begin(page, pos, len, get_block);
-		if (unlikely(ret))
-			goto out_release;
-		return ret;
-	}
-
-	if (PageMappedToDisk(page))
-		return 0;
-
-	/*
-	 * Allocate buffers so that we can keep track of state, and potentially
-	 * attach them to the page if an error occurs. In the common case of
-	 * no error, they will just be freed again without ever being attached
-	 * to the page (which is all OK, because we're under the page lock).
-	 *
-	 * Be careful: the buffer linked list is a NULL terminated one, rather
-	 * than the circular one we're used to.
-	 */
-	head = alloc_page_buffers(page, blocksize, false);
-	if (!head) {
-		ret = -ENOMEM;
-		goto out_release;
-	}
-
-	block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
-
-	/*
-	 * We loop across all blocks in the page, whether or not they are
-	 * part of the affected region.  This is so we can discover if the
-	 * page is fully mapped-to-disk.
-	 */
-	for (block_start = 0, block_in_page = 0, bh = head;
-		  block_start < PAGE_SIZE;
-		  block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
-		int create;
-
-		block_end = block_start + blocksize;
-		bh->b_state = 0;
-		create = 1;
-		if (block_start >= to)
-			create = 0;
-		ret = get_block(inode, block_in_file + block_in_page,
-					bh, create);
-		if (ret)
-			goto failed;
-		if (!buffer_mapped(bh))
-			is_mapped_to_disk = 0;
-		if (buffer_new(bh))
-			clean_bdev_bh_alias(bh);
-		if (PageUptodate(page)) {
-			set_buffer_uptodate(bh);
-			continue;
-		}
-		if (buffer_new(bh) || !buffer_mapped(bh)) {
-			zero_user_segments(page, block_start, from,
-							to, block_end);
-			continue;
-		}
-		if (buffer_uptodate(bh))
-			continue;	/* reiserfs does this */
-		if (block_start < from || block_end > to) {
-			lock_buffer(bh);
-			bh->b_end_io = end_buffer_read_nobh;
-			submit_bh(REQ_OP_READ, bh);
-			nr_reads++;
-		}
-	}
-
-	if (nr_reads) {
-		/*
-		 * The page is locked, so these buffers are protected from
-		 * any VM or truncate activity.  Hence we don't need to care
-		 * for the buffer_head refcounts.
-		 */
-		for (bh = head; bh; bh = bh->b_this_page) {
-			wait_on_buffer(bh);
-			if (!buffer_uptodate(bh))
-				ret = -EIO;
-		}
-		if (ret)
-			goto failed;
-	}
-
-	if (is_mapped_to_disk)
-		SetPageMappedToDisk(page);
-
-	*fsdata = head; /* to be released by nobh_write_end */
-
-	return 0;
-
-failed:
-	BUG_ON(!ret);
-	/*
-	 * Error recovery is a bit difficult. We need to zero out blocks that
-	 * were newly allocated, and dirty them to ensure they get written out.
-	 * Buffers need to be attached to the page at this point, otherwise
-	 * the handling of potential IO errors during writeout would be hard
-	 * (could try doing synchronous writeout, but what if that fails too?)
-	 */
-	attach_nobh_buffers(page, head);
-	page_zero_new_buffers(page, from, to);
-
-out_release:
-	unlock_page(page);
-	put_page(page);
-	*pagep = NULL;
-
-	return ret;
-}
-EXPORT_SYMBOL(nobh_write_begin);
-
-int nobh_write_end(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned copied,
-			struct page *page, void *fsdata)
-{
-	struct inode *inode = page->mapping->host;
-	struct buffer_head *head = fsdata;
-	struct buffer_head *bh;
-	BUG_ON(fsdata != NULL && page_has_buffers(page));
-
-	if (unlikely(copied < len) && head)
-		attach_nobh_buffers(page, head);
-	if (page_has_buffers(page))
-		return generic_write_end(file, mapping, pos, len,
-					copied, page, fsdata);
-
-	SetPageUptodate(page);
-	set_page_dirty(page);
-	if (pos+copied > inode->i_size) {
-		i_size_write(inode, pos+copied);
-		mark_inode_dirty(inode);
-	}
-
-	unlock_page(page);
-	put_page(page);
-
-	while (head) {
-		bh = head;
-		head = head->b_this_page;
-		free_buffer_head(bh);
-	}
-
-	return copied;
-}
-EXPORT_SYMBOL(nobh_write_end);
-
-/*
- * nobh_writepage() - based on block_full_write_page() except
- * that it tries to operate without attaching bufferheads to
- * the page.
- */
-int nobh_writepage(struct page *page, get_block_t *get_block,
-			struct writeback_control *wbc)
-{
-	struct inode * const inode = page->mapping->host;
-	loff_t i_size = i_size_read(inode);
-	const pgoff_t end_index = i_size >> PAGE_SHIFT;
-	unsigned offset;
-	int ret;
-
-	/* Is the page fully inside i_size? */
-	if (page->index < end_index)
-		goto out;
-
-	/* Is the page fully outside i_size? (truncate in progress) */
-	offset = i_size & (PAGE_SIZE-1);
-	if (page->index >= end_index+1 || !offset) {
-		unlock_page(page);
-		return 0; /* don't care */
-	}
-
-	/*
-	 * The page straddles i_size.  It must be zeroed out on each and every
-	 * writepage invocation because it may be mmapped.  "A file is mapped
-	 * in multiples of the page size.  For a file that is not a multiple of
-	 * the  page size, the remaining memory is zeroed when mapped, and
-	 * writes to that region are not written out to the file."
-	 */
-	zero_user_segment(page, offset, PAGE_SIZE);
-out:
-	ret = mpage_writepage(page, get_block, wbc);
-	if (ret == -EAGAIN)
-		ret = __block_write_full_page(inode, page, get_block, wbc,
-					      end_buffer_async_write);
-	return ret;
-}
-EXPORT_SYMBOL(nobh_writepage);
-
-int nobh_truncate_page(struct address_space *mapping,
-			loff_t from, get_block_t *get_block)
-{
-	pgoff_t index = from >> PAGE_SHIFT;
-	struct inode *inode = mapping->host;
-	unsigned blocksize = i_blocksize(inode);
-	struct folio *folio;
-	struct buffer_head map_bh;
-	size_t offset;
-	sector_t iblock;
-	int err;
-
-	/* Block boundary? Nothing to do */
-	if (!(from & (blocksize - 1)))
-		return 0;
-
-	folio = __filemap_get_folio(mapping, index, FGP_LOCK | FGP_CREAT,
-			mapping_gfp_mask(mapping));
-	err = -ENOMEM;
-	if (!folio)
-		goto out;
-
-	if (folio_buffers(folio))
-		goto has_buffers;
-
-	iblock = from >> inode->i_blkbits;
-	map_bh.b_size = blocksize;
-	map_bh.b_state = 0;
-	err = get_block(inode, iblock, &map_bh, 0);
-	if (err)
-		goto unlock;
-	/* unmapped? It's a ho