buffer: use mapping_set_error instead of setting the flag

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/buffer.c

@@ -482,7 +482,7 @@ static void __remove_assoc_queue(struct buffer_head *bh)
 	list_del_init(&bh->b_assoc_buffers);
 	WARN_ON(!bh->b_assoc_map);
 	if (buffer_write_io_error(bh))
-		set_bit(AS_EIO, &bh->b_assoc_map->flags);
+		mapping_set_error(bh->b_assoc_map, -EIO);
 	bh->b_assoc_map = NULL;
 }