[DRBD-user] [RFC] DRBD9 - compat cleanup - everybody can help

[Roland Kammerer]

Dear users,

tl;tr: download, compile-test (& try) this release, which is 9.0.14 + 2
very noncritical cleanup patches.

we are currently cleaning up our compat code. This code is used to
ensure that the out-of-tree module builds against all kinds of kernels.

Over the years that collected code back to very very ancient kernels.
Time to clean that up a bit.

What happend:
- I compiled the latest release against all kernels where LINBIT
  provides support. These are *a lot*. Different distributions,
  different kernels.
- I collected the generated compat.hs and checked which defines are the
  same in all compat.hs.
- Deleted these checks, and adapted the code.

It would be great if you could compile the resulting code. Even compile
tests help. Extra points for loading/testing the resulting module. Maybe
not on Friday in production ;-). This is WIP and needs more careful
review.

So how far back is this expected to work: The oldest kernel we target
for DRBD9 is the one from RHEL6 (aka. 2.6.32 + hectoliters of RedHat
special sauce). So RHEL6 with 2.6.32 has to work, which does not mean it
compiles against a Linux upstream 2.6.32 tag).

What was compile tested is:
debian-jessie, debian-stretch, oracle7, rhel6, rhel7, sles11-sp4,
sles12, ubuntu-bionic, ubuntu-trusty, ubuntu-xenial, xenserver6,
xenserver7. With various kernels (e.g., from every RHEL dot-release) and
various flavours (like ubuntu AWS kernels).

Every feedback is welcome, mainly I'm interested in breakage of the
mentioned distributions/kernels, but not so much for
$specialsnowflakelinux.

http://packages.linbit.com/rckcompat/drbd-9.0.14-1.tar.gz

Thanks, rck