Comment 13 for bug 1601997

Initial comments from the email:-

a) There is some confusion over "metadata_csum" with/without "64bit". -- Those who have 'reverted' are usually reverting BOTH flags [as I've done some places], not just metadata_csum.
My understanding is 64bit is of no benefit except support >16TB fs and to strengthen metadata_csum's [if used, which help notice dodgy disks in theory.].

b) The business of including e2fsprogs-1.44.0 in 18.04 at tytso's request [NON-default extra feature support may benefit Samba users etc. later] is not addressed.

c) Its' worth pointing-out explicitly e2fsprogs only enabled 64bit,metadata_csum 'by default' for 'everybody' within last few weeks, Debian change was as-you-rightly-quote.

d) Considering the above, also think outside the ubuntu-box! What do canonical's customers/partners expect compatibility-wise with other non-ubuntu systems, virtualizers/ISCSI-hosts/etc (e2fsprogs 1.42 still very common!), let alone "backports to ubuntu LTS versions" only?.

e) My understanding from TJ in IRC is he's started doing some tests on some datacentre cases, there are particular issues with things like ISCSI hosts, the host system needs to fsck guest-FS and break otherwise!. HOPEFULLY this will appear soon and can be added to the mail-discussion.

I can try to join email/post directly to mail if appropriate/helpful.