It's too late. Might work or not (and on buster it doesn't).

Remove fil_node_t::sync_event.

I had a discussion with kernel fellows and they said it's safe to call
fsync() simultaneously at least on VFS and ext4. So initially I wanted
to disable check for recent Linux but than I realized code is buggy.

Consider a case when one thread is inside fsync() and two others are
waiting inside os_event. First thread after fsync() calls os_event_set()
which is a broadcast! So two waiting threads will awake and may call
fsync() at the same time.

One fix is to add a notify_one() functionality to os_event but I decided
to remove incorrect check completely. Note, it works for one waiting
thread but not for more than one.

IMO it's ok to avoid existing bugs but there is not too much sense in
avoiding possible(!) bugs as this code does.

fil_space_t::is_in_rotation_list(), fil_space_t::is_in_unflushed_spaces():
Replace redundant bool fields with member functions.

fil_node_t::needs_flush: Replaces fil_node_t::modification_counter and
fil_node_t::flush_counter. We need to know whether there _are_ some
unflushed writes and we do not need to know _how many_ writes.

fil_system_t::modification_counter: Remove as not needed.
Even if we needed fil_node_t::modification_counter, every file
could have its own counter that would be incremented on each write.

fil_system_t::modification_counter is a global modification counter
for all files. It was incremented on every write. But whether some
file was flushed or not is an internal fil_node_t deal/state and
this makes fil_system_t::modification_counter useless.

Closes #1061

Add a simplest regression test. Specifically, I want to be sure that
SYS_COLUMNS.LEN is increased.

Closes #1123

Use the same data type 'ulong' to avoid type mismatch on Windows
and on 32-bit systems.

FIXME: The correct data type should probably be 64-bit.

When innobase_allocate_row_for_vcol() returns true (for failure),
it may already have invoked mem_heap_create(). However, some callers
would fail to invoke mem_heap_free().

pcre needs symbols from pcreposix
(but this is only an issue when linking with system static libraries)

Problem:
========
Server fails to notify the engine by not setting the ADD_PK_INDEX and
DROP_PK_INDEX When there is a
 i) Change in candidate for primary key.
 ii) New candidate for primary key.

Fix:
====
Server sets the ADD_PK_INDEX and DROP_PK_INDEX while doing alter for the
above problematic case.

I missed this in commit 9a7281a7

PROBLEM
-------

1. We are inserting a base column entry which causes an invalid value
   by the function provided to generate virtual column,but we go ahead
   and insert this due to ignore keyword.
2. We then delete this record, making this record delete marked in innodb.
   If we try to insert another record with the same pk as the deleted
   record and if the rec is not purged ,then we try to undelete mark this
   record and try to build a update vector with previous and updated value
   and while calculating the value of virtual column we get error from
   server that we cannot calculate this from base column.
   Innodb assumes that innobase_get_computed_value() Should always return
   a valid value for the base column present in the row. The failure of
   this call was not handled ,so we were crashing.

FIX

Thanks to commit 2614a0ab
before MDEV-5800, no version of MariaDB is affected by this bug
that was fixed in MySQL 5.7.25.

10.1 part: SHOW CREATE USER didn't show the password, if plugin was set,
but authentication_string was not

remove tests that rely on specific execution order

remove tests that rely on specific execution order

MDEV-17421: mtr does not restart the server whose parameters were changed

           32 bit int

Row-based slave applier could not parse correctly the table id when
the value exceeded the max of 32 bit unsigned int.
The reason turns out in that the being parsed value placeholder
was sized as 4 bytes.

The type is fixed to ulonglong.

Additionally the patch works around Rows_log_event::m_table_id 4 bytes
size on 32 bits platforms. In case of last_table_id value overflows
the 4 byte max, there won't be the zero value for m_table_id generated
and the first wrapped-around value is one, this is thanks to excluding
UINT_MAX32 + 1 from TABLE_SHARE::table_map_id.

Rename it because it caused parser warning whenever --backup was used.

dict_sys_get_size(): Replace the time-consuming loop with
a crude estimate that can be computed without holding any mutex.

Even before dict_sys->size was removed in MDEV-13325,
not all memory allocations by the InnoDB data dictionary cache
were being accounted for. One example is foreign key constraints.
Another example is virtual column metadata, starting with 10.2.

on startup innodb is checking whether files "ib_logfileN"
(for N from 1 to 100) exist, and whether they're readable.
A non-existent file aborted the scan.
A directory instead of a file made InnoDB to fail.

Now it treats "directory exists" as "file doesn't exist".

When InnoDB is invoking posix_fallocate() to extend data files, it
was missing a call to fsync() to update the file system metadata.
If file system recovery is needed, the file size could be incorrect.

When the setting innodb_flush_method=O_DIRECT_NO_FSYNC
that was introduced in MariaDB 10.0.11 (and MySQL 5.6) is enabled,
InnoDB would wrongly skip fsync() after extending files.

Furthermore, the merge commit d8b45b0c
inadvertently removed XtraDB error checking for posix_fallocate()
which this fix is restoring.

fil_flush(): Add the parameter bool metadata=false to request that
fil_buffering_disabled() be ignored.

fil_extend_space_to_desired_size(): Invoke fil_flush() with the
extra parameter. After successful posix_fallocate(), invoke
os_file_flush(). Note: The bookkeeping for fil_flush() would not be
updated the posix_fallocate() code path, so the "redundant"
fil_flush() should be a no-op.

thd_destructor_proxy() may miss abort signal if innobase_end() is running
concurrently, which causes server hang in pthread_join() on shutdown.

The problem was that aborting wasn't protected by mutex:
proxy thr: while (!myvar->abort)
end thr: running->abort = 1;
end thr: mysql_cond_broadcast(...);
proxy thr: mysql_cond_wait(...); // nobody to awake it
end thr: pthread_join(...); // waits for proxy thr

Also made main.mysqld_option_err reentrant.

increase to 1M

MDEV-17973: Don't overwrite xtrabackup-v2/mariabackup SST logs by def…

In the function QUICK_RANGE_SELECT::init_ror_merged_scan we create a seperate handler if the handler in
head->file cannot be reused. The flag free_file tells us if we have a seperate handler or not.
There are cases where you might create a handler and then there might be a failure(running ALTER)
and then we have to revert the handler back to the original one. The code does that
but it does not reset the flag 'free_file' in this case.
Also backported f2c41807.

row_drop_table_for_mysql(): Fix a regression introduced in MDEV-16515.
Similar to the follow-up fixes MDEV-16647 and MDEV-17470, we must make
the internal tables of FULLTEXT INDEX immune to kills, to avoid noise
and resource leakage on DROP TABLE or ALTER TABLE. (Orphan internal tables
would be dropped at the next InnoDB startup only.)

server shutdown.

Prior to adding current thd to the global thd list, initialize
thd->mysys_var->current_cond / thd->mysys_var->current_mutex.

Otherwise thd_destructor_proxy can miss the abort condition, which is set
by the shutdown thread.