nfs: Convert from launder_page to launder_folio

We don't need to use page_file_mapping() here because launder_folio
is never called for swap cache pages.  We also don't need to
cast an loff_t in order to print it.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Mike Marshall <hubcap@omnibond.com> # orangefs
Tested-by: David Howells <dhowells@redhat.com> # afs

fs/nfs/file.c

@@ -472,15 +472,15 @@ static void nfs_check_dirty_writeback(struct page *page,
  * - Caller holds page lock
  * - Return 0 if successful, -error otherwise
  */
-static int nfs_launder_page(struct page *page)
+static int nfs_launder_folio(struct folio *folio)
 {
-	struct inode *inode = page_file_mapping(page)->host;
+	struct inode *inode = folio->mapping->host;
 
-	dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
-		inode->i_ino, (long long)page_offset(page));
+	dfprintk(PAGECACHE, "NFS: launder_folio(%ld, %llu)\n",
+		inode->i_ino, folio_pos(folio));
 
-	wait_on_page_fscache(page);
-	return nfs_wb_page(inode, page);
+	folio_wait_fscache(folio);
+	return nfs_wb_page(inode, &folio->page);
 }
 
 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
@@ -526,7 +526,7 @@ const struct address_space_operations nfs_file_aops = {
 #ifdef CONFIG_MIGRATION
 	.migratepage = nfs_migrate_page,
 #endif
-	.launder_page = nfs_launder_page,
+	.launder_folio = nfs_launder_folio,
 	.is_dirty_writeback = nfs_check_dirty_writeback,
 	.error_remove_page = generic_error_remove_page,
 	.swap_activate = nfs_swap_activate,