On Thu, Oct 31, 2019 at 04:50:45PM -0400, Theodore Y. Ts'o wrote:

One of the reasons I really want this is so I (as an upstream
maintainer of ext4 and fscrypt) can test the new code paths using
xfstests on GCE, without needing special pre-release hardware that has
the ICE support.

Yeah, I could probably get one of those dev boards internally at
Google, but they're a pain in the tuckus to use, and I'd much rather
be able to have my normal test infrastructure using gce-xfstests and
kvm-xfstests be able to test inline-crypto.  So in terms of CI
testing, having the blk-crypto is really going to be helpful.

Implementing the support in qemu or a special device mapper mode
seems like a much better idea for that use case over carrying the
code in the block layer and severely bloating the per-I/O data
structure.