On Sun, Dec 18, 2016 at 06:17:55PM -0500, Mike Snitzer wrote:

Spinning it as a pure bugfix is a reach (as Eric's header documents the
patch, the case is weak for cc'ing stable).  Reality is the change is
needed to enable a new bcache feature.  I'm not going to rush
feature-enabling change that arrived in the last minute.

I do agree that it can wait for 4.11 and isn't a candidate for stable, I
should've said that earlier.

quoted

and you can't fault Eric for not
wanting to do work on dm-cache too when all he's trying to do is solve a
particular real world problem. He should be able to do that without having to
dive into dm-cache code too.

Furthermore, pretty much every filesystem has private ioctls and interfaces -
this is no different.

You're completely misreading my having raised dm-cache.  I was poinitng
out that Eric's patch to enable a new bcache feature ontop of dm-crypt
was too late.  Had Eric known of this limitation sooner or thought to
engage me or the rest of dm-devel then DM could've been fixed with
precision during the 4.10 development window.

I wasn't saying Eric should've worked on dm-cache.  But had he raised
this bcache feature to my attention, in the context of missing ioprio
and why dm-cache would/could use it in the future too, then it'd have
been all the better.  Simple as that.  I was trying to be helpful.  Not
trying to be a PITA in any way.

I took your email to mean that the original patches shouldn't have gone in
without involving dm-cache. If that wasn't what you meant, let's just chalk this
up to a miscommunication.