The fix of MDEV-23456 (commit b1009ae5)
introduced a livelock between page flushing and a thread that is
executing buf_page_create().

buf_page_create(): If the current mini-transaction is holding
an exclusive latch on the page, do not attempt to acquire another
one, and do not care about any I/O fix.

mtr_t::have_x_latch(): Replaces mtr_t::get_fix_count().

dyn_buf_t::for_each_block(const Functor&) const: A new variant.

rw_lock_own(): Add a const qualifier.

Reviewed by: Thirunarayanan Balathandayuthapani

Due to a premature cleanup of the unit that specified a recursive CTE
used in the second operand of union the server fell into an infinite
loop in the reported test case. In other cases this premature cleanup
could cause other problems.
The bug is the result of a not quite correct fix for MDEV-17024. The
unit that specifies a recursive CTE has to be cleaned only after the
cleanup of the last external reference to this CTE. It means that
cleanups of the unit triggered not by the cleanup of a external
reference to the CTE must be blocked.
Usage of local table chains in selects to get external references to
recursive CTEs was not correct either because of possible merges of
some selects.

Also fixed a minor bug in st_select_lex::set_explain_type() that caused
typing 'RECURSIVE UNION' instead of 'UNION' in EXPLAIN output for external
references to a recursive CTE.

Analysis:
========
Writes to 'rli->log_space_total' needs to be synchronized, otherwise both
SQL_THREAD and IO_THREAD can try to modify the variable simultaneously
resulting in incorrect rli->log_space_total.  In the current test scenario
SQL_THREAD is trying to decrement 'rli->log_space_total' in 'purge_first_log'
and IO_THREAD is trying to increment the 'rli->log_space_total' in
'queue_event' simultaneously. Hence test occasionally fails with  result
mismatch.

Fix:
===
Convert 'rli->log_space_total' variable to atomic type.

MDEV-12353 deliberately tries to avoid memory alignment overhead in
log_phys_t, storing the stream of log records bytes straight after
a header object. But, offsetof() is not allowed on C++ data objects,
and neither are attempts to emulate it by invoking a member function
on a null pointer.

log_phys_t::len: Remove. Make it part of the byte stream that
immediately follow the object. Thanks to Eugene Kosov for this idea.

log_phys_t::start(): The start address of the following byte stream.

log_phys_t::len(): Compute len.

log_phys_t::alloc_size(): Use a simple sizeof calculation.

A follow-up fix, for original fix for MDEV-21577, which did not handle well
temporary tables.

OPTIMIZE and REPAIR TABLE statements can take a list of tables as argument,
and some of the tables may be temporary. Proper handling of temporary tables
is to skip them and continue working on the real tables. The bad version, skipped all tables,
if a single temporary table was in the argument list. And this resulted so that FK parent
tables were not scnanned for the remaining real tables. Some mtr tests, using OPTIMIZE or REPAIR
for temporary tables caused regressions bacause of this, e.g. galera.galera_optimize_analyze_multi

The fix in this PR opens temporary and real tables first, and in the table handling loop skips
temporary tables, FK parent scanning is done only for real tables.

The test has new scenario for OPTIMIZE and REPAIR issued for two tables of which one is temporary table.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

This PR fixes same issue as MDEV-21577 for TRUNCATE TABLE.
MDEV-21577 fixed TOI replication for OPTIMIZE, REPAIR and ALTER TABLE
operating on FK child table. It was later found out that also TRUNCATE
has similar problem and needs a fix.

The actual fix is to do FK parent table lookup before TRUNCATE TOI
isolation and append found FK parent table names in certification key
list for the write set.

PR contains also new test scenario in galera_ddl_fk_conflict test where
FK child has two FK parent tables and there are two DML transactions operating
on both parent tables.

For development convenience, new TO isolation macro was added:
WSREP_TO_ISOLATION_BEGIN_IF and WSREP_TO_ISOLATION_BEGIN_ALTER macro was changed
to skip the goto statement.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

As noted in commit 0b66d3f7,
MariaDB does not support CREATE TABLESPACE for InnoDB.
Hence, some code that was added in
commit fec844ac
and originally in
mysql/mysql-server@c71dd213bd434c0579e454ab8880e6d3756b0fb0
is unused in MariaDB and should be removed.

trx_undo_left(): Return 0 in case of an overflow, instead of
returning a negative number interpreted as a large positive number.
Also, add debug assertions to check that the pointer is within
the page area. This should allow us to catch bugs like
MDEV-24096 easier in the future.

The function ibuf_merge_or_delete_for_page() was always being
invoked with update_ibuf_bitmap=true ever since
commit cd623508
fixed up something after MDEV-9566.

Furthermore, the parameter page_size is never being passed as a
null pointer, and therefore it should better be a reference to
a constant object.

MDEV-24190 Accessing INFORMATION_SCHEMA.INNODB_TABLESPACES_ENCRYPTION may break innodb_open_files logic

If the function i_s_tablespaces_encryption_fill_table() was not able to
report all content to the SQL layer, it would fail to decrement
fil_system.freeze_space_list that it had incremented. This would
prevent the not-frequently-used logic from working, potentially causing
frequently used files to be closed and reopened whenever innodb_open_files
is exceeded.

This regression was caused by
commit 45ed9dd9 (part of MDEV-23855).

Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

- Patch 95bb3cb8 used `my_which` function in `10.2`
- Based on patch `355ee687` from 10.3+ `command -v` is used instead of
`my_which` so we are changing in this patch also
- `ldconfig` is usually found in `/sbin` so make sure it is added in
`$PATH` variable

- Patch is solving generating report on warning
        To repeat the error run single worker:
        ```
        ./mtr --mysqld=--lock-wait-timeout=-xx 1st 1st --force --parallel 1
        ```
        or `N` workers with `N+1` tests with failures and `force`
        ```
        ./mtr --mysqld=--lock-wait-timeout=-xx 1st 1st grant5 --force --parallel 2
        ```
- Patch is doing cosmetic fix of `current_test` log file which holds the old log value of test `CURRENT TEST:..` in `mark_log()` in case of `unknown option` and as such
  the logic which is using it's content doesn't output valid log content and doesn't generate valid `$test->{'comment'}` message.asdf

- Closing the socket/handler after the removing the handler from IO for
consistency

Reviewed by: serg@mariadb.com