Ondrej Kozina authored Jan 15, 2018 and Milan Broz committed Jan 18, 2018

cryptsetup now requires dm-crypt v1.18.1 or higher
to use kernel keyring service for passing VKs.

Also, relevant API functions fail if CRYPT_ACTIVATE_KEYRING_KEY
is set, but library is not allowed to use kernel keyring for
VK.