Make sure that when we publish the crypt_data we access the
memory cache of the tablespace crypt_data. Make sure that
crypt_data is stored whenever it is really needed.
All this is not yet enough in my opinion because:
sql/encryption.cc has DBUG_ASSERT(scheme->type == 1) i.e.
crypt_data->type == CRYPT_SCHEME_1
However, for InnoDB point of view we have global crypt_data
for every tablespace. When we change variables on crypt_data
we take mutex. However, when we use crypt_data for
encryption/decryption we use pointer to this global
structure and no mutex to protect against changes on
crypt_data.
Tablespace encryption starts in fil_crypt_start_encrypting_space
from crypt_data that has crypt_data->type = CRYPT_SCHEME_UNENCRYPTED
and later we write page 0 CRYPT_SCHEME_1 and finally whe publish
that to memory cache.
Analysis: Problem was that tablespaces not encrypted might not have
crypt_data stored on disk.
Fixed by always creating crypt_data to memory cache of the tablespace.
MDEV-8138: strange results from encrypt-and-grep test
Analysis: crypt_data->type is not updated correctly on memory
cache. This caused problem with state tranfer on
encrypted => unencrypted => encrypted.
Fixed by updating memory cache of crypt_data->type correctly based on
current srv_encrypt_tables value to either CRYPT_SCHEME_1 or
CRYPT_SCHEME_UNENCRYPTED.
Analysis: Problem was that we did create crypt data for encrypted table but
this new crypt data was not written to page 0. Instead a default crypt data
was written to page 0 at table creation.
Fixed by explicitly writing new crypt data to page 0 after successfull
table creation.
fix encryption of the last partial block
* now really encrypt it, using key and iv
* support the case of very short plaintext (less than one block)
* recommend aes_ctr over aes_cbc, because the former
doesn't have problems with partial blocks
