need to pick a solution for dm-crypt IV generation and do it! [was: Re: dm: submit stacked requests in irq enabled context]

[Mike Snitzer <snitzer@redhat.com>]

On Wed, May 10 2017 at  9:37am -0400,
Gilad Ben-Yossef <gilad@benyossef.com> wrote:

> On Wed, May 10, 2017 at 11:49 AM, Neeraj Soni <neersoni@codeaurora.org> wrote:
> > Hi Keith,
> >
> > Request based dm (dm-req-crypt) is being used for Disk Encryption solution
> > in Android used by Google. Also as i mentioned reverting this fix  improves
> > the RR/RW numbers so this proves the request based dm is coming into path
> > and is being used.
> 
> Sadly, that is an out of tree module.
> 
> Does it still use Qcom specific APIs in its implementation (qcrypto_* funcs)?
> It did the last time I've checked - and the driver that implements
> those is not upstream either...
> 
> It makes it difficult to help - which is a shame since I am interested
> in enabling higher performance
> of dm-crypt when using HW based crypto transformation myself.

I have absolutely no interest in request-based dm-crypt.  It is a hack
to work-around limitations in crypto IV generation.

If "google" is foolish enough to deploy out-of-tree request-based
dm-crypt in their android kernel then they are easily capable of
reverting the commit in question to prop up their short-cited decision.

The correct way forward is to follow through with the crypto work
discussed here (pick a solution to implement and make it happen):
https://www.redhat.com/archives/dm-devel/2017-March/msg00044.html
and here:
https://www.redhat.com/archives/dm-devel/2017-March/msg00053.html
and here:
https://www.redhat.com/archives/dm-devel/2017-April/msg00132.html

Mike