For QA purposes, here#s the explanation about the problem, quoted from the commit message: +If sectorsize is not BTRFS_SUPER_INFO_SIZE (4k), the superblock checksum +is wrong and mkfs fails. This has been reported on ppc64 where we pick +sectorisize from page size (64k). This has been broken since ages +(2008) and discovered by the recently added superblock checks.