No issue on read_page0 (number of times page 0 is read) vs page_0_crypt_read (is crypt data read or not).

http://lists.askmonty.org/pipermail/commits/2016-December/010358.html

jplindst, fil_space_t::read_page0 is bool, it cannot be "number of times".

Ah, confused i to ulint_ctr_64_t page0_read

This patch appears to address serg’s comment:
http://lists.askmonty.org/pipermail/commits/2016-December/010361.html

commit a0d396fd3f5f86e09f602ac9f76b8d9f2e739221
Author: Jan Lindström <jan.lindstrom@mariadb.com>
Date: Tue Jan 3 14:35:08 2017 +0200

MDEV-11684: post-10.1-merge fixes

10.1 is merged into 10.2 now. Two issues are left to fix:
(1) encryption.innochecksum test
(2) read_page0 vs page_0_crypt_read

(1) innochecksum tool did not compile after merge because
buf_page_is_corrupted uses fil_crypt_t that has been changed.

extra/CMakeLists.txt: Added fil/fil0crypt.cc as dependency
as we need to use fil_crypt_verify_checksum for encrypted pages.

innochecksum.cc: If we think page is encrypted i.e.
FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION != 0 we call
fil_crypt_verify_checksum() function to compare calculated
checksum to stored checksum calculated after encryption
(this is stored on different offset i.e.
FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION + 4).
If checksum does not match we call normal buf_page_is_corrupted
to compare calculated checksum to stored checksum.

fil0crypt.cc: add #ifdef UNIV_INNOCHECKSUM to be able to compile
this file for innochecksum tool.

(2) read_page0 is not needed and thus removed.