On Wed, Aug 31 2016 at  2:26am -0400,
Milan Broz [off-list ref] wrote:

On 08/31/2016 12:27 AM, Mikulas Patocka wrote:

...

quoted

Drop that "#ifdef CONFIG_BCACHE". Anyone should be allowed to create a big 
bio, not just bcache.

Yes. Please, do not hide it behind #ifdef.
If it is in code, it should be enabled always.

There can third party modules or some new code appears and creating strange
config dependence only adds more problems later.

I did last night, see:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.8&id=4e870e948fbabf62b78e8410f04c67703e7c816b

Will go to Linus for v4.8-rc5 by the end of the week.