InnoDB has several times changed its redo log format by introducing
new redo log record types. Format changes would lead to misleading
reports of redo log corruption when processing individual redo log
records.

In the redo log header (start of the ib_logfile0 file), we will introduce
a format version identifier and textual representation of the software
version that created the redo log files.

Furthermore, we change the checksum of redo log checkpoint pages, so that
older versions of MySQL will refuse to start up on redo log files that
were created with a MySQL server that includes this fix.

We will also remove a number of unused fields from the redo log
header and checkpoint pages (pages 0, 1, and 3).

Some tests will be expanded, because with this fix,
the server must refuse to start up with older redo log files,
unless they are dirty.

We will also replace the configuration parameter
innodb_log_checksum_algorithm with the Boolean parameter
innodb_log_checksums.
We make CRC-32C the only checksum on the InnoDB redo log pages when
innodb_log_checksums=ON (the default). Checksums on the header page
and the checkpoint pages are never disabled.

innodb_log_checksums_func_update(), innodb_log_checksums_update():
Update triggers for the new global Boolean variable innodb_log_checksums.

innodb_log_checksum_func_update(), innodb_log_checksum_algorithm_update():
Removed along with the global parameter innodb_log_checksum_algorithm.

Removed definitions:
LOG_MAX_N_GROUPS
log_group_read_checkpoint_info()
log_checkpoint_get_nth_group_info()
log_checkpoint_set_nth_group_info()
log_block_calc_checksum_innodb()
log_block_calc_checksum_crc32_legacy_big_endian()
recv_check_cp_is_consistent()
log_block_checksum_weak_validation()
log_block_checksum_what_matches()
log_block_checksum_fail_fatal()
log_block_checksum_is_ok_or_old_format()
LOG_CHECKPOINT_OFFSET_LOW32
LOG_CHECKPOINT_ARCHIVED_LSN
LOG_CHECKPOINT_GROUP_ARRAY
LOG_CHECKPOINT_ARCHIVED_FILE_NO
LOG_CHECKPOINT_ARCHIVED_OFFSET
LOG_CHECKPOINT_ARRAY_END
LOG_CHECKPOINT_CHECKSUM_1
LOG_CHECKPOINT_CHECKSUM_2
LOG_CHECKPOINT_FSP_FREE_LIMIT
LOG_CHECKPOINT_FSP_MAGIC_N
LOG_CHECKPOINT_FSP_MAGIC_N_VAL
LOG_CHECKPOINT_OFFSET_HIGH32
LOG_CHECKPOINT_SIZE
LOG_GROUP_ID
LOG_FILE_START_LSN
LOG_FILE_NO
LOG_FILE_WAS_CREATED_BY_HOT_BACKUP
LOG_FILE_ARCH_COMPLETED
LOG_FILE_END_LSN

Changed definitions:
LOG_CHECKPOINT_LOG_BUF_SIZE

Added definitions:
innodb_log_checksums: The current value of the SET GLOBAL variable.
LOG_CHECKPOINT_OFFSET
LOG_HEADER_FORMAT (repurposing LOG_GROUP_ID which was always 0)
LOG_HEADER_PAD1 (unused 4 bytes, zero-initialized)
LOG_HEADER_START_LSN
LOG_HEADER_CREATOR (renamed from LOG_FILE_WAS_CREATED_BY_HOT_BACKUP)
LOG_HEADER_CREATOR_END
LOG_HEADER_CREATOR_CURRENT
LOG_HEADER_FORMAT_CURRENT
log_group_t::format

log_block_calc_checksum_format_0(): Renamed from
log_block_calc_checksum_innodb(). This is only used when upgrading the
redo log from non-tagged format.

recv_find_max_checkpoint_0(): New function, used when upgrading the
redo log from non-tagged format.

recv_log_format_0_recover(): New function, used when upgrading the
redo log from non-tagged format. Checks if the redo log is clean.

log_group_header_read(): Replaces log_group_read_checkpoint_info().
Also used for reading the log header page (page 0).

recv_check_log_header_checksum(): Replaces recv_check_cp_is_consistent().
Also used for checking the log header page (page 0).

log_block_checksum_is_ok(): Checks a log block checksum. It must either
be CRC-32C, or we must have innodb_log_checksums=OFF.

Changed functions:

log_group_file_header_flush(): Always zero-initialize the buffer
and initialize all LOG_HEADER_ fields.

log_group_checkpoint(): Zero-initialize the checkpoint buffer,
and write the checkpoint in the new format, with CRC-32C checksum.

recv_find_max_checkpoint(): Support both the old log format
(if the old-format redo log is logically empty) and the new format.

recv_scan_log_recs(): Clean up the logic a bit. Display a message
when encountering (and terminating log parsing due to) invalid
log blocks. For now, keep the existing behaviour and do not display
a message about log block header mismatch.

recv_recovery_from_checkpoint_start(): Replace the whole "ibbackup" label.
Check if a log upgrade or a normal recovery is needed.

srv_prepare_to_delete_redo_log_files(): Display a message about
upgrading the redo log.

Other changes to startup:

If we are going to upgrade the redo log, we must avoid writing any
new redo log records before we have replaced the redo log.

dict_check_sys_tablespaces(), dict_check_sys_tables(): Avoid
updating SYS_DATAFILES if we are going to upgrade the redo log.

dict_create_or_check_sys_virtual(): Do not modify anything if we are
running in --innodb-read-only or --innodb-force-recovery=6 mode.

RB: 10096
Reviewed-by: Kevin Lewis <kevin.lewis@oracle.com>
Reviewed-by: Annamalai Gurusami <annamalai.gurusami@oracle.com>