On Fri, Jun 02, 2017 at 05:46:22AM -0700, Tahsin Erdogan wrote: > > Hmm... normally we'd supply sbi->s_csum_seed as the second argument so > > that the metadata checksum value also has the fs uuid stamped into it. > > I have thought about using sbi->s_csum_seed and was a little hesitant > because it involves adding more complexity to e2fsprogs to handle > cases like changing uuid or turning off metadata_csum. After thinking > more about this, I think it is doable. e2fsprogs already has code to walk the fs to rewrite/remove checksums, so it shouldn't be too much effort to tap into that to rewrite the ea_info hash. > > Even if you dismiss that, we usually follow the convention of > > initializing the crc32c calculation with (~0U), not (0U), to strengthen > > crc32c's ability to detect zeroes being injected at the start of the > > stream. > > Agreed, using ~0 is definitely better than 0. --D
