BTRFS_MAP_GET_READ_MIRRORS
ret = btrfs_map_block(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
if (io_geom->op == BTRFS_MAP_GET_READ_MIRRORS && nr_extra_stripes == 2) {
ret = btrfs_map_block(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,