Problem:
=======
Autoincrement value gives duplicate values because of the following reasons.

(1) In InnoDB handler function, current autoincrement value is not changed
based on newly set auto_increment_increment or auto_increment_offset variable.

(2) Handler function does the rounding logic and changes the current
autoincrement value and InnoDB doesn't aware of the change in current
autoincrement value.

Solution:
========
Fix the problem(1), InnoDB always respect the auto_increment_increment
and auto_increment_offset value in case of current autoincrement value.
By fixing the problem (2), handler layer won't change any current
autoincrement value.
Reviewed-by: Jimmy Yang <jimmy.yang@oracle.com>
RB: 13748

Backport WL#9383 INNODB: ADD AN OPTION TO TURN OFF/ON DEADLOCK CHECKER
(rb#12873) to 5.7.

Analysis:
When we access fts_internal_tbl_name in i_s_fts_config_fill (),
it can be set to NULL by another session.

Solution:
Define fts_internal_tbl_name2 for global variable innodb_ft_aux_table,
if it's NULL, set fts_internal_tbl_name to "default".
Reviewed-by: Jimmy Yang <jimmy.yang@oracle.com>
RB: 13401

Alias the InnoDB ulint and lint data types to size_t and ssize_t,
which are the standard names for the machine-word-width data types.

Correspondingly, define ULINTPF as "%zu" and introduce ULINTPFx as "%zx".
In this way, better compiler warnings for type mismatch are possible.

Furthermore, use PRIu64 for that 64-bit format, and define
the feature macro __STDC_FORMAT_MACROS to enable it on Red Hat systems.

Fix some errors in error messages, and replace some error messages
with assertions.
Most notably, an IMPORT TABLESPACE error message in InnoDB was
displaying the number of columns instead of the mismatching flags.

ha_innobase::defragment_table(): Skip corrupted indexes and
FULLTEXT INDEX. In InnoDB, FULLTEXT INDEX is implemented with
auxiliary tables. We will not defragment them on OPTIMIZE TABLE.

InnoDB divides the allocation of undo logs into rollback segments.
The DB_ROLL_PTR system column of clustered indexes can address up to
128 rollback segments (TRX_SYS_N_RSEGS). Originally, InnoDB only
created one rollback segment. In MySQL 5.5 or in the InnoDB Plugin
for MySQL 5.1, all 128 rollback segments were created.

MySQL 5.7 hard-codes the rollback segment IDs 1..32 for temporary undo logs.
On upgrade, unless a slow shutdown (innodb_fast_shutdown=0)
was performed on the old server instance, these rollback segments
could be in use by transactions that are in XA PREPARE state or
transactions that were left behind by a server kill followed by a
normal shutdown immediately after restart.

Persistent tables cannot refer to temporary undo logs or vice versa.
Therefore, we should keep two distinct sets of rollback segments:
one for persistent tables and another for temporary tables. In this way,
all 128 rollback segments will be available for both types of tables,
which could improve performance. Also, MariaDB 10.2 will remain more
compatible than MySQL 5.7 with data files from earlier versions of
MySQL or MariaDB.

trx_sys_t::temp_rsegs[TRX_SYS_N_RSEGS]: A new array of temporary
rollback segments. The trx_sys_t::rseg_array[TRX_SYS_N_RSEGS] will
be solely for persistent undo logs.

srv_tmp_undo_logs. Remove. Use the constant TRX_SYS_N_RSEGS.

srv_available_undo_logs: Change the type to ulong.

trx_rseg_get_on_id(): Remove. Instead, let the callers refer to
trx_sys directly.

trx_rseg_create(), trx_sysf_rseg_find_free(): Remove unneeded parameters.
These functions only deal with persistent undo logs.

trx_temp_rseg_create(): New function, to create all temporary rollback
segments at server startup.

trx_rseg_t::is_persistent(): Determine if the rollback segment is for
persistent tables.

trx_sys_is_noredo_rseg_slot(): Remove. The callers must know based on
context (such as table handle) whether the DB_ROLL_PTR is referring to
a persistent undo log.

trx_sys_create_rsegs(): Remove all parameters, which were always passed
as global variables. Instead, modify the global variables directly.

enum trx_rseg_type_t: Remove.

trx_t::get_temp_rseg(): A method to ensure that a temporary
rollback segment has been assigned for the transaction.

trx_t::assign_temp_rseg(): Replaces trx_assign_rseg().

trx_purge_free_segment(), trx_purge_truncate_rseg_history():
Remove the redundant variable noredo=false.
Temporary undo logs are discarded immediately at transaction commit
or rollback, not lazily by purge.

trx_purge_mark_undo_for_truncate(): Remove references to the
temporary rollback segments.

trx_purge_mark_undo_for_truncate(): Remove a check for temporary
rollback segments. Only the dedicated persistent undo log tablespaces
can be truncated.

trx_undo_get_undo_rec_low(), trx_undo_get_undo_rec(): Add the
parameter is_temp.

trx_rseg_mem_restore(): Split from trx_rseg_mem_create().
Initialize the undo log and the rollback segment from the file
data structures.

trx_sysf_get_n_rseg_slots(): Renamed from
trx_sysf_used_slots_for_redo_rseg(). Count the persistent
rollback segment headers that have been initialized.

trx_sys_close(): Also free trx_sys->temp_rsegs[].

get_next_redo_rseg(): Merged to trx_assign_rseg_low().

trx_assign_rseg_low(): Remove the parameters and access the
global variables directly. Revert to simple round-robin, now that
the whole trx_sys->rseg_array[] is for persistent undo log again.

get_next_noredo_rseg(): Moved to trx_t::assign_temp_rseg().

srv_undo_tablespaces_init(): Remove some parameters and use the
global variables directly. Clarify some error messages.

Adjust the test innodb.log_file. Apparently, before these changes,
InnoDB somehow ignored missing dedicated undo tablespace files that
are pointed by the TRX_SYS header page, possibly losing part of
essential transaction system state.

trx::has_logged_persistent(): Renamed from trx_is_redo_rseg_updated().
Determines if a transaction has generated any persistent undo log.

trx::has_logged(): Renamed from trx_is_rseg_updated().
Determines if a transaction has generated any undo log.

give threads more descriptive names

Follow-up to
Bug#21141390: REMOVE UNUSED FUNCTIONS AND CONVERT GLOBAL SYMBOLS TO STATIC
but for variables instead of functions.

Was identified with the -Wmissing-variable-declarations
compiler warning option supported by Clang 3.6.
Reviewed-by: Marko Mäkelä <marko.makela@oracle.com>

RB: 9070

InnoDB defines some functions that are not called at all.
Other functions are called, but only from the same compilation unit.

Remove some function declarations and definitions, and add 'static'
keywords. Some symbols must be kept for separately compiled tools,
such as innochecksum.

MDEV-11581: Mariadb starts InnoDB encryption threads
when key has not changed or data scrubbing turned off

Background: Key rotation is based on background threads
(innodb-encryption-threads) periodically going through
all tablespaces on fil_system. For each tablespace
current used key version is compared to max key age
(innodb-encryption-rotate-key-age). This process
naturally takes CPU. Similarly, in same time need for
scrubbing is investigated. Currently, key rotation
is fully supported on Amazon AWS key management plugin
only but InnoDB does not have knowledge what key
management plugin is used.

This patch re-purposes innodb-encryption-rotate-key-age=0
to disable key rotation and background data scrubbing.
All new tables are added to special list for key rotation
and key rotation is based on sending a event to
background encryption threads instead of using periodic
checking (i.e. timeout).

fil0fil.cc: Added functions fil_space_acquire_low()
to acquire a tablespace when it could be dropped concurrently.
This function is used from fil_space_acquire() or
fil_space_acquire_silent() that will not print
any messages if we try to acquire space that does not exist.
fil_space_release() to release a acquired tablespace.
fil_space_next() to iterate tablespaces in fil_system
using fil_space_acquire() and fil_space_release().
Similarly, fil_space_keyrotation_next() to iterate new
list fil_system->rotation_list where new tables.
are added if key rotation is disabled.
Removed unnecessary functions fil_get_first_space_safe()
fil_get_next_space_safe()

fil_node_open_file(): After page 0 is read read also
crypt_info if it is not yet read.

btr_scrub_lock_dict_func()
buf_page_check_corrupt()
buf_page_encrypt_before_write()
buf_merge_or_delete_for_page()
lock_print_info_all_transactions()
row_fts_psort_info_init()
row_truncate_table_for_mysql()
row_drop_table_for_mysql()
    Use fil_space_acquire()/release() to access fil_space_t.

buf_page_decrypt_after_read():
    Use fil_space_get_crypt_data() because at this point
    we might not yet have read page 0.

fil0crypt.cc/fil0fil.h: Lot of changes. Pass fil_space_t* directly
to functions needing it and store fil_space_t* to rotation state.
Use fil_space_acquire()/release() when iterating tablespaces
and removed unnecessary is_closing from fil_crypt_t. Use
fil_space_t::is_stopping() to detect when access to
tablespace should be stopped. Removed unnecessary
fil_space_get_crypt_data().

fil_space_create(): Inform key rotation that there could
be something to do if key rotation is disabled and new
table with encryption enabled is created.
Remove unnecessary functions fil_get_first_space_safe()
and fil_get_next_space_safe(). fil_space_acquire()
and fil_space_release() are used instead. Moved
fil_space_get_crypt_data() and fil_space_set_crypt_data()
to fil0crypt.cc.

fsp_header_init(): Acquire fil_space_t*, write crypt_data
and release space.

check_table_options()
	Renamed FIL_SPACE_ENCRYPTION_* TO FIL_ENCRYPTION_*

i_s.cc: Added ROTATING_OR_FLUSHING field to
information_schema.innodb_tablespace_encryption
to show current status of key rotation.

Define my_thread_id as an unsigned type, to avoid mismatch with
ulonglong.  Change some parameters to this type.

Use size_t in a few more places.

Declare many flag constants as unsigned to avoid sign mismatch
when shifting bits or applying the unary ~ operator.

When applying the unary ~ operator to enum constants, explictly
cast the result to an unsigned type, because enum constants can
be treated as signed.

In InnoDB, change the source code line number parameters from
ulint to unsigned type. Also, make some InnoDB functions return
a narrower type (unsigned or uint32_t instead of ulint;
bool instead of ibool).

The InnoDB adaptive hash index is sometimes degrading the performance of
InnoDB, and it is sometimes disabled to get more consistent performance.
We should have a compile-time option to disable the adaptive hash index.

Let us introduce two options:

OPTION(WITH_INNODB_AHI "Include innodb_adaptive_hash_index" ON)
OPTION(WITH_INNODB_ROOT_GUESS "Cache index root block descriptors" ON)

where WITH_INNODB_AHI always implies WITH_INNODB_ROOT_GUESS.

As part of this change, the misleadingly named function
trx_search_latch_release_if_reserved(trx) will be replaced with the macro
trx_assert_no_search_latch(trx) that will be empty unless
BTR_CUR_HASH_ADAPT is defined (cmake -DWITH_INNODB_AHI=ON).

We will also remove the unused column
INFORMATION_SCHEMA.INNODB_TRX.TRX_ADAPTIVE_HASH_TIMEOUT.
In MariaDB Server 10.1, it used to reflect the value of
trx_t::search_latch_timeout which could be adjusted during
row_search_for_mysql(). In 10.2, there is no such field.

Other than the removal of the unused column TRX_ADAPTIVE_HASH_TIMEOUT,
this is an almost non-functional change to the server when using the
default build options.

Some tests are adjusted so that they will work with both
-DWITH_INNODB_AHI=ON and -DWITH_INNODB_AHI=OFF. The test
innodb.innodb_monitor has been renamed to innodb.monitor
in order to track MySQL 5.7, and the duplicate tests
sys_vars.innodb_monitor_* are removed.

MDEV-7618 introduced configuration parameter innodb_instrument_semaphores
in MariaDB Server 10.1. The parameter seems to only affect the rw-lock
X-latch acquisition. Extra fields are added to rw_lock_t to remember one
X-latch holder or waiter. These fields are not being consulted or reported
anywhere. This is basically only adding code bloat.

If the intention is to debug hangs or deadlocks, we have better tools for
that in the debug server, and for the non-debug server, core dumps can
reveal a lot. For example, the mini-transaction memo records the
currently held buffer block or index rw-locks, to be released at
mtr_t::commit().

The configuration parameter innodb_instrument_semaphores will be
deprecated in 10.2.5 and removed in 10.3.0.

rw_lock_t: Remove the members lock_name, file_name, line, thread_id
which did not affect any output.

to tables in the system tablespace

This is a regression caused by MDEV-11585, which accidentally
changed Tablespace::is_undo_tablespace() in an incorrect way,
causing the InnoDB system tablespace to be reported as a dedicated
undo tablespace, for which the change buffer is not applicable.

Tablespace::is_undo_tablespace(): Remove. There were only 2
calls from the function buf_page_io_complete(). Replace those
calls as appropriate.

Also, merge changes to tablespace import/export tests from
MySQL 5.7, and clean up the tests a little further, allowing
them to be run with any innodb_page_size.

Remove duplicated error injection instrumentation for the
import/export tests.  In MySQL 5.7, the error injection label
buf_page_is_corrupt_failure was renamed to
buf_page_import_corrupt_failure.

fil_space_extend_must_retry(): Correct a debug assertion
(tablespaces can be extended during IMPORT), and remove a
TODO comment about compressed temporary tables that was
already addressed in MDEV-11816.

dict_build_tablespace_for_table(): Correct a comment that
no longer holds after MDEV-11816, and assert that
ROW_FORMAT=COMPRESSED can only be used in .ibd files.

innobase_get_stmt_safe(): Copy also the last byte.

dict_init_free(): Make global, and move the call from
dict_close() to srv_free(), because this is initialized
earlier than dict_sys.

innobase_space_shutdown(): Do not leak srv_allow_writes_event.

Write only one encryption key to the checkpoint page.
Use 4 bytes of nonce. Encrypt more of each redo log block,
only skipping the 4-byte field LOG_BLOCK_HDR_NO which the
initialization vector is derived from.

Issue notes, not warning messages for rewriting the redo log files.

recv_recovery_from_checkpoint_finish(): Do not generate any redo log,
because we must avoid that before rewriting the redo log files, or
otherwise a crash during a redo log rewrite (removing or adding
encryption) may end up making the database unrecoverable.
Instead, do these tasks in innobase_start_or_create_for_mysql().

Issue a firm "Missing MLOG_CHECKPOINT" error message. Remove some
unreachable code and duplicated error messages for log corruption.

LOG_HEADER_FORMAT_ENCRYPTED: A flag for identifying an encrypted redo
log format.

log_group_t::is_encrypted(), log_t::is_encrypted(): Determine
if the redo log is in encrypted format.

recv_find_max_checkpoint(): Interpret LOG_HEADER_FORMAT_ENCRYPTED.

srv_prepare_to_delete_redo_log_files(): Display NOTE messages about
adding or removing encryption. Do not issue warnings for redo log
resizing any more.

innobase_start_or_create_for_mysql(): Rebuild the redo logs also when
the encryption changes.

innodb_log_checksums_func_update(): Always use the CRC-32C checksum
if innodb_encrypt_log. If needed, issue a warning
that innodb_encrypt_log implies innodb_log_checksums.

log_group_write_buf(): Compute the checksum on the encrypted
block contents, so that transmission errors or incomplete blocks can be
detected without decrypting.

Rewrite most of the redo log encryption code. Only remember one
encryption key at a time (but remember up to 5 when upgrading from the
MariaDB 10.1 format.)

The InnoDB redo log consists of a list of files that logically form
a bigger file, as if the individual files were concatenated together.

The first file will always be written on redo log checkpoint, because
the two checkpoint pages are at the start of the single logical
redo log file.

There is no technical reason why InnoDB requires at least 2 files
to exist. Let us reduce the minimum number to 1. In that way,
restoring from backups will become easier, since InnoDB can directly
deal with a single backed-up redo log file.

Ever since MDEV-5800 enabled indexed virtual columns for InnoDB,
the InnoDB shutdown relied on close_connections() that would set
thd->killed for the InnoDB purge threads. Alas, the embedded server
shutdown is not invoking close_connections(), and thus InnoDB purge
threads fail to initiate shutdown, causing a hang.

innodb_inited: Remove. Use srv_was_started instead.

innobase_fast_shutdown: Remove. Use srv_fast_shutdown instead.

srv_running: Renamed from thd_destructor_myvar, and made global.
The value NULL means that shutdown was requested or the purge threads
should not be running because of innodb_read_only_mode=1.

innobase_init(): Set srv_was_started after ensuring that srv_running
was initialized. (In innodb_read_only mode, the purge threads are not
started and we do not care if srv_running==NULL.)

innobase_start_or_create_for_mysql(): Do not set srv_was_started.
Let it be set by the only caller innobase_init().

srv_purge_should_exit(): Check also srv_was_started and srv_running
when evaluating thd->killed.

because it doesn't work, vcols are never calculated for ICP

Oracle introduced a Memcached plugin interface to the InnoDB
storage engine in MySQL 5.6. That interface is essentially a
fork of Memcached development snapshot 1.6.0-beta1 of an old
development branch 'engine-pu'.

To my knowledge, there have not been any updates to the Memcached code
between MySQL 5.6 and 5.7; only bug fixes and extensions related to
the Oracle modifications.

The Memcached plugin is not part of the MariaDB Server. Therefore it
does not make sense to include the InnoDB interfaces for the Memcached
plugin, or to have any related configuration parameters:

    innodb_api_bk_commit_interval
    innodb_api_disable_rowlock
    innodb_api_enable_binlog
    innodb_api_enable_mdl
    innodb_api_trx_level

Removing this code in one commit makes it possible to easily restore
it, in case it turns out to be needed later.

innodb_autoinc_lock_mode            = 2
innodb_buffer_pool_dump_at_shutdown = ON
innodb_buffer_pool_dump_pct         = 25
innodb_buffer_pool_load_at_startup  = ON
innodb_checksum_algorithm           = CRC32
innodb_file_format                  = Barracuda
innodb_large_prefix                 = ON
innodb_log_compressed_pages         = ON
innodb_purge_threads                = 4
innodb_strict_mode                  = ON
binlog_annotate_row_events          = ON
binlog_format                       = MIXED
binlog-row-event-max-size           = 8192
group_concat_max_len                = 1M
lock_wait_timeout                   = 86400
log_slow_admin_statements           = ON
log_slow_slave_statements           = ON
log_warnings                        = 2
max_allowed_packet                  = 16M
replicate_annotate_row_events       = ON
slave_net_timeout                   = 60
sync_binlog                         = 1
aria_recover                        = BACKUP,QUICK
myisam_recover_options              = BACKUP,QUICK

Encryption stores used key_version to
FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION (offset 26)
field. Spatial indexes store RTREE Split Sequence Number
(FIL_RTREE_SPLIT_SEQ_NUM) in the same field. Both values
can't be stored in same field. Thus, current encryption
implementation does not support encrypting spatial indexes.

fil_space_encrypt(): Do not encrypt page if page type is
FIL_PAGE_RTREE (this is required for background
encryption innodb-encrypt-tables=ON).

create_table_info_t::check_table_options() Do not allow creating
table with ENCRYPTED=YES if table contains spatial index.

Galera disallow-writes feature was lost in InnoDB 5.7 merge
to 10.2. This patch restores this feature and fixes test
failure on test galera.galera_var_innodb_disallow_writes.

Remove the debug parameter innodb_force_recovery_crash that was
introduced into MySQL 5.6 by me in WL#6494 which allowed InnoDB
to resize the redo log on startup.

Let innodb.log_file_size actually start up the server, but ensure
that the InnoDB storage engine refuses to start up in each of the
scenarios.

This fixes memory leaks in tests that cause InnoDB startup to fail.

buf_pool_free_instance(): Also free buf_pool->flush_rbt, which would
normally be freed when crash recovery finishes.

fil_node_close_file(), fil_space_free_low(), fil_close_all_files():
Relax some debug assertions to tolerate !srv_was_started.

innodb_shutdown(): Renamed from innobase_shutdown_for_mysql().
Changed the return type to void. Do not assume that all subsystems
were started.

que_init(), que_close(): Remove (empty functions).

srv_init(), srv_general_init(): Remove as global functions.

srv_free(): Allow srv_sys=NULL.

srv_get_active_thread_type(): Only return SRV_PURGE if purge really
is running.

srv_shutdown_all_bg_threads(): Do not reset srv_start_state. It will
be needed by innodb_shutdown().

innobase_start_or_create_for_mysql(): Always call srv_boot() so that
innodb_shutdown() can assume that it was called. Make more subsystems
dependent on SRV_START_STATE_STAT.

srv_shutdown_bg_undo_sources(): Require SRV_START_STATE_STAT.

trx_sys_close(): Do not assume purge_sys!=NULL. Do not call
buf_dblwr_free(), because the doublewrite buffer can exist while
the transaction system does not.

logs_empty_and_mark_files_at_shutdown(): Do a faster shutdown if
!srv_was_started.

recv_sys_close(): Invoke dblwr.pages.clear() which would normally
be invoked by buf_dblwr_process().

recv_recovery_from_checkpoint_start(): Always release log_sys->mutex.

row_mysql_close(): Allow the subsystem not to exist.

Display a NOTE, not a WARNING for non-default page size.

Remove duplicated output and change output level to info.

Remove the debug parameter innodb_force_recovery_crash that was
introduced into MySQL 5.6 by me in WL#6494 which allowed InnoDB
to resize the redo log on startup.

Let innodb.log_file_size actually start up the server, but ensure
that the InnoDB storage engine refuses to start up in each of the
scenarios.

this fixes the crash in innodb.101_compatibility test

1. wait for thd_destructor_proxy thread to start after creating it.
   this ensures that the thread is ready to receive a shutdown signal
   whenever we want to send it.
2. join it at shutdown, this guarantees that no innodb THD will exist
   after innobase_end().

this fixes crashes and memory leaks in main.mysqld_option_err
(were innodb was started and then immediately shut down).

crashes server

This bug is the result of merging the Oracle MySQL follow-up fix
BUG#22963169 MYSQL CRASHES ON CREATE FULLTEXT INDEX
without merging the base bug fix:
Bug#79475 Insert a token of 84 4-bytes chars into fts index causes
server crash.

Unlike the above mentioned fixes in MySQL, our fix will not change
the storage format of fulltext indexes in InnoDB or XtraDB
when a character encoding with mbmaxlen=2 or mbmaxlen=3
and the length of a word is between 128 and 84*mbmaxlen bytes.
The Oracle fix would allocate 2 length bytes for these cases.

Compatibility with other MySQL and MariaDB releases is ensured by
persisting the used maximum length in the SYS_COLUMNS table in the
InnoDB data dictionary.

This fix also removes some unnecessary strcmp() calls when checking
for the legacy default collation my_charset_latin1
(my_charset_latin1.name=="latin1_swedish_ci").

fts_create_one_index_table(): Store the actual length in bytes.
This metadata will be written to the SYS_COLUMNS table.

fts_zip_initialize(): Initialize only the first byte of the buffer.
Actually the code should not even care about this first byte, because
the length is set as 0.

FTX_MAX_WORD_LEN: Define as HA_FT_MAXCHARLEN * 4 aka 336 bytes,
not as 254 bytes.

row_merge_create_fts_sort_index(): Set the actual maximum length of the
column in bytes, similar to fts_create_one_index_table().

row_merge_fts_doc_tokenize(): Remove the redundant parameter word_dtype.
Use the actual maximum length of the column. Calculate the extra_size
in the same way as row_merge_buf_encode() does.

Problem was that implementation merged from 10.1 was incompatible
with InnoDB 5.7.

buf0buf.cc: Add functions to return should we punch hole and
how big.

buf0flu.cc: Add written page to IORequest

fil0fil.cc: Remove unneeded status call and add test is
sparse files and punch hole supported by file system when
tablespace is created. Add call to get file system
block size. Used file node is added to IORequest. Added
functions to check is punch hole supported and setting
punch hole.

ha_innodb.cc: Remove unneeded status variables (trim512-32768)
and trim_op_saved. Deprecate innodb_use_trim and
set it ON by default. Add function to set innodb-use-trim
dynamically.

dberr.h: Add error code DB_IO_NO_PUNCH_HOLE
if punch hole operation fails.

fil0fil.h: Add punch_hole variable to fil_space_t and
block size to fil_node_t.

os0api.h: Header to helper functions on buf0buf.cc and
fil0fil.cc for os0file.h

os0file.h: Remove unneeded m_block_size from IORequest
and add bpage to IORequest to know actual size of
the block and m_fil_node to know tablespace file
system block size and does it support punch hole.

os0file.cc: Add function punch_hole() to IORequest
to do punch_hole operation,
get the file system block size and determine
does file system support sparse files (for punch hole).

page0size.h: remove implicit copy disable and
use this implicit copy to implement copy_from()
function.

buf0dblwr.cc, buf0flu.cc, buf0rea.cc, fil0fil.cc, fil0fil.h,
os0file.h, os0file.cc, log0log.cc, log0recv.cc:
Remove unneeded write_size parameter from fil_io
calls.

srv0mon.h, srv0srv.h, srv0mon.cc: Remove unneeded
trim512-trim32678 status variables. Removed
these from monitor tests.

Change default to zlib, this has effect only if user has
explicitly requested page compression and then user
naturally expects that pages are really compressed
if they can be compressed.