ntfs3: remove ->writepage

->writepage is a very inefficient method to write back data, and only used
through write_cache_pages or a a fallback when no ->migrate_folio method
is present.

Set ->migrate_folio to the generic buffer_head based helper, and remove
the ->writepage implementation.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Christoph Hellwig <[e-mail]>
Cc: Jan Kara <[e-mail]>
Cc: Joel Becker <[e-mail]>
Cc: Joseph Qi <[e-mail]>
Cc: Konstantin Komarov <[e-mail]>
Cc: Mark Fasheh <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Theodore Ts'o <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

fs/ntfs3/inode.c

···
 	return err;
 }
 
-static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
-{
-	struct address_space *mapping = page->mapping;
-	struct inode *inode = mapping->host;
-	struct ntfs_inode *ni = ntfs_i(inode);
-	int err;
-
-	if (is_resident(ni)) {
-		ni_lock(ni);
-		err = attr_data_write_resident(ni, page);
-		ni_unlock(ni);
-		if (err != E_NTFS_NONRESIDENT) {
-			unlock_page(page);
-			return err;
-		}
-	}
-
-	return block_write_full_page(page, ntfs_get_block, wbc);
-}
-
 static int ntfs_resident_writepage(struct page *page,
 		struct writeback_control *wbc, void *data)
 {
···
 const struct address_space_operations ntfs_aops = {
 	.read_folio	= ntfs_read_folio,
 	.readahead	= ntfs_readahead,
-	.writepage	= ntfs_writepage,
 	.writepages	= ntfs_writepages,
 	.write_begin	= ntfs_write_begin,
 	.write_end	= ntfs_write_end,
 	.direct_IO	= ntfs_direct_IO,
 	.bmap		= ntfs_bmap,
 	.dirty_folio	= block_dirty_folio,
+	.migrate_folio	= buffer_migrate_folio,
 	.invalidate_folio = block_invalidate_folio,
 };