dm_array_cursor_begin
r = dm_array_cursor_begin(&cmd->info, cmd->root, &cmd->mapping_cursor);
r = dm_array_cursor_begin(&cmd->hint_info, cmd->hint_root, &cmd->hint_cursor);
EXPORT_SYMBOL_GPL(dm_array_cursor_begin);
int dm_array_cursor_begin(struct dm_array_info *info,
r = dm_array_cursor_begin(&info->array_info, root, &c->cursor);