mariadb/storage/innobase/fil/fil0fil.cc

/*****************************************************************************

Copyright (c) 1995, 2017, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2014, 2020, MariaDB Corporation.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA

*****************************************************************************/

/**************************************************//**
@file fil/fil0fil.cc
The tablespace memory cache

Created 10/25/1995 Heikki Tuuri
*******************************************************/

#include "fil0fil.h"
#include "fil0crypt.h"

#include "btr0btr.h"
#include "buf0buf.h"
#include "dict0boot.h"
#include "dict0dict.h"
#include "dict0load.h"
#include "fsp0file.h"
#include "fsp0fsp.h"
#include "hash0hash.h"
#include "log0log.h"
#include "log0recv.h"
#include "mach0data.h"
#include "mtr0log.h"
#include "os0file.h"
#include "page0zip.h"
#include "row0mysql.h"
#include "srv0start.h"
#include "trx0purge.h"
#include "buf0lru.h"
#include "ibuf0ibuf.h"
#include "os0event.h"
#include "sync0sync.h"
#include "buf0flu.h"
#include "os0api.h"
#ifdef UNIV_LINUX
# include <sys/types.h>
# include <sys/sysmacros.h>
# include <dirent.h>
#endif

/** Tries to close a file in the LRU list. The caller must hold the fil_sys
mutex.
@return true if success, false if should retry later; since i/o's
generally complete in < 100 ms, and as InnoDB writes at most 128 pages
from the buffer pool in a batch, and then immediately flushes the
files, there is a good chance that the next time we find a suitable
node from the LRU list.
@param[in] print_info	if true, prints information why it
                        cannot close a file */
static
bool
fil_try_to_close_file_in_LRU(bool print_info);

/** Test if a tablespace file can be renamed to a new filepath by checking
if that the old filepath exists and the new filepath does not exist.
@param[in]	old_path	old filepath
@param[in]	new_path	new filepath
@param[in]	is_discarded	whether the tablespace is discarded
@param[in]	replace_new	whether to ignore the existence of new_path
@return innodb error code */
static dberr_t
fil_rename_tablespace_check(
	const char*	old_path,
	const char*	new_path,
	bool		is_discarded,
	bool		replace_new = false);
/** Rename a single-table tablespace.
The tablespace must exist in the memory cache.
@param[in]	id		tablespace identifier
@param[in]	old_path	old file name
@param[in]	new_name	new table name in the
databasename/tablename format
@param[in]	new_path_in	new file name,
or NULL if it is located in the normal data directory
@return true if success */
static bool
fil_rename_tablespace(
	ulint		id,
	const char*	old_path,
	const char*	new_name,
	const char*	new_path_in);

/*
		IMPLEMENTATION OF THE TABLESPACE MEMORY CACHE
		=============================================

The tablespace cache is responsible for providing fast read/write access to
tablespaces and logs of the database. File creation and deletion is done
in other modules which know more of the logic of the operation, however.

A tablespace consists of a chain of files. The size of the files does not
have to be divisible by the database block size, because we may just leave
the last incomplete block unused. When a new file is appended to the
tablespace, the maximum size of the file is also specified. At the moment,
we think that it is best to extend the file to its maximum size already at
the creation of the file, because then we can avoid dynamically extending
the file when more space is needed for the tablespace.

A block's position in the tablespace is specified with a 32-bit unsigned
integer. The files in the chain are thought to be catenated, and the block
corresponding to an address n is the nth block in the catenated file (where
the first block is named the 0th block, and the incomplete block fragments
at the end of files are not taken into account). A tablespace can be extended
by appending a new file at the end of the chain.

Our tablespace concept is similar to the one of Oracle.

To acquire more speed in disk transfers, a technique called disk striping is
sometimes used. This means that logical block addresses are divided in a
round-robin fashion across several disks. Windows NT supports disk striping,
so there we do not need to support it in the database. Disk striping is
implemented in hardware in RAID disks. We conclude that it is not necessary
to implement it in the database. Oracle 7 does not support disk striping,
either.

Another trick used at some database sites is replacing tablespace files by
raw disks, that is, the whole physical disk drive, or a partition of it, is
opened as a single file, and it is accessed through byte offsets calculated
from the start of the disk or the partition. This is recommended in some
books on database tuning to achieve more speed in i/o. Using raw disk
certainly prevents the OS from fragmenting disk space, but it is not clear
if it really adds speed. We measured on the Pentium 100 MHz + NT + NTFS file
system + EIDE Conner disk only a negligible difference in speed when reading
from a file, versus reading from a raw disk.

To have fast access to a tablespace or a log file, we put the data structures
to a hash table. Each tablespace and log file is given an unique 32-bit
identifier.

Some operating systems do not support many open files at the same time,
though NT seems to tolerate at least 900 open files. Therefore, we put the
open files in an LRU-list. If we need to open another file, we may close the
file at the end of the LRU-list. When an i/o-operation is pending on a file,
the file cannot be closed. We take the file nodes with pending i/o-operations
out of the LRU-list and keep a count of pending operations. When an operation
completes, we decrement the count and return the file node to the LRU-list if
the count drops to zero. */

/** Reference to the server data directory. Usually it is the
current working directory ".", but in the MySQL Embedded Server Library
it is an absolute path. */
const char*	fil_path_to_mysql_datadir;

/** Common InnoDB file extensions */
const char* dot_ext[] = { "", ".ibd", ".isl", ".cfg" };

/** Number of pending tablespace flushes */
ulint	fil_n_pending_tablespace_flushes	= 0;

/** The tablespace memory cache. This variable is NULL before the module is
initialized. */
fil_system_t	fil_system;

/** At this age or older a space/page will be rotated */
UNIV_INTERN extern uint srv_fil_crypt_rotate_key_age;
UNIV_INTERN extern ib_mutex_t fil_crypt_threads_mutex;

/** Determine if the space id is a user tablespace id or not.
@param[in]	space_id	Space ID to check
@return true if it is a user tablespace ID */
inline
bool
fil_is_user_tablespace_id(ulint space_id)
{
	return(space_id != TRX_SYS_SPACE
	       && space_id != SRV_TMP_SPACE_ID
	       && !srv_is_undo_tablespace(space_id));
}

#ifdef UNIV_DEBUG
/** Try fil_validate() every this many times */
# define FIL_VALIDATE_SKIP	17

/******************************************************************//**
Checks the consistency of the tablespace cache some of the time.
@return true if ok or the check was skipped */
static
bool
fil_validate_skip(void)
/*===================*/
{
	/** The fil_validate() call skip counter. */
	static Atomic_counter<uint32_t> fil_validate_count;

	/* We want to reduce the call frequency of the costly fil_validate()
	check in debug builds. */
	return (fil_validate_count++ % FIL_VALIDATE_SKIP) || fil_validate();
}
#endif /* UNIV_DEBUG */

/********************************************************************//**
Determines if a file node belongs to the least-recently-used list.
@return true if the file belongs to fil_system.LRU mutex. */
UNIV_INLINE
bool
fil_space_belongs_in_lru(
/*=====================*/
	const fil_space_t*	space)	/*!< in: file space */
{
	switch (space->purpose) {
	case FIL_TYPE_TEMPORARY:
		return(false);
	case FIL_TYPE_TABLESPACE:
		return(fil_is_user_tablespace_id(space->id));
	case FIL_TYPE_IMPORT:
		return(true);
	}

	ut_ad(0);
	return(false);
}

/********************************************************************//**
NOTE: you must call fil_mutex_enter_and_prepare_for_io() first!

Prepares a file node for i/o. Opens the file if it is closed. Updates the
pending i/o's field in the node and the system appropriately. Takes the node
off the LRU list if it is in the LRU list. The caller must hold the fil_sys
mutex.
@return false if the file can't be opened, otherwise true */
static
bool
fil_node_prepare_for_io(
/*====================*/
	fil_node_t*	node,	/*!< in: file node */
	fil_space_t*	space);	/*!< in: space */

/*******************************************************************//**
Returns the table space by a given id, NULL if not found.
It is unsafe to dereference the returned pointer. It is fine to check
for NULL. */
fil_space_t*
fil_space_get_by_id(
/*================*/
	ulint	id)	/*!< in: space id */
{
	fil_space_t*	space;

	ut_ad(fil_system.is_initialised());
	ut_ad(mutex_own(&fil_system.mutex));

	HASH_SEARCH(hash, fil_system.spaces, id,
		    fil_space_t*, space,
		    ut_ad(space->magic_n == FIL_SPACE_MAGIC_N),
		    space->id == id);

	return(space);
}

/** Look up a tablespace.
The caller should hold an InnoDB table lock or a MDL that prevents
the tablespace from being dropped during the operation,
or the caller should be in single-threaded crash recovery mode
(no user connections that could drop tablespaces).
If this is not the case, fil_space_acquire() and fil_space_t::release()
should be used instead.
@param[in]	id	tablespace ID
@return tablespace, or NULL if not found */
fil_space_t*
fil_space_get(
	ulint	id)
{
	mutex_enter(&fil_system.mutex);
	fil_space_t*	space = fil_space_get_by_id(id);
	mutex_exit(&fil_system.mutex);
	return(space);
}

/** Returns the latch of a file space.
@param[in]	id	space id
@param[out]	flags	tablespace flags
@return latch protecting storage allocation */
rw_lock_t*
fil_space_get_latch(
	ulint	id,
	ulint*	flags)
{
	fil_space_t*	space;

	ut_ad(fil_system.is_initialised());

	mutex_enter(&fil_system.mutex);

	space = fil_space_get_by_id(id);

	ut_a(space);

	if (flags) {
		*flags = space->flags;
	}

	mutex_exit(&fil_system.mutex);

	return(&(space->latch));
}

/**********************************************************************//**
Checks if all the file nodes in a space are flushed.
@return true if all are flushed */
static
bool
fil_space_is_flushed(
/*=================*/
	fil_space_t*	space)	/*!< in: space */
{
	ut_ad(mutex_own(&fil_system.mutex));

	for (const fil_node_t* node = UT_LIST_GET_FIRST(space->chain);
	     node != NULL;
	     node = UT_LIST_GET_NEXT(chain, node)) {

		if (node->needs_flush) {
			ut_ad(srv_file_flush_method != SRV_O_DIRECT_NO_FSYNC);
			return(false);
		}
	}

	return(true);
}

/** Validate the compression algorithm for full crc32 format.
@param[in]	space	tablespace object
@return whether the compression algorithm support */
static bool fil_comp_algo_validate(const fil_space_t* space)
{
	if (!space->full_crc32()) {
		return true;
	}

	DBUG_EXECUTE_IF("fil_comp_algo_validate_fail",
			return false;);

	ulint	comp_algo = space->get_compression_algo();
	switch (comp_algo) {
	case PAGE_UNCOMPRESSED:
	case PAGE_ZLIB_ALGORITHM:
#ifdef HAVE_LZ4
	case PAGE_LZ4_ALGORITHM:
#endif /* HAVE_LZ4 */
#ifdef HAVE_LZO
	case PAGE_LZO_ALGORITHM:
#endif /* HAVE_LZO */
#ifdef HAVE_LZMA
	case PAGE_LZMA_ALGORITHM:
#endif /* HAVE_LZMA */
#ifdef HAVE_BZIP2
	case PAGE_BZIP2_ALGORITHM:
#endif /* HAVE_BZIP2 */
#ifdef HAVE_SNAPPY
	case PAGE_SNAPPY_ALGORITHM:
#endif /* HAVE_SNAPPY */
		return true;
	}

	return false;
}

/** Append a file to the chain of files of a space.
@param[in]	name		file name of a file that is not open
@param[in]	handle		file handle, or OS_FILE_CLOSED
@param[in]	size		file size in entire database pages
@param[in]	is_raw		whether this is a raw device
@param[in]	atomic_write	true if atomic write could be enabled
@param[in]	max_pages	maximum number of pages in file,
or ULINT_MAX for unlimited
@return file object */
fil_node_t* fil_space_t::add(const char* name, pfs_os_file_t handle,
			     ulint size, bool is_raw, bool atomic_write,
			     ulint max_pages)
{
	fil_node_t*	node;

	ut_ad(name != NULL);
	ut_ad(fil_system.is_initialised());

	node = reinterpret_cast<fil_node_t*>(ut_zalloc_nokey(sizeof(*node)));

	node->handle = handle;

	node->name = mem_strdup(name);

	ut_a(!is_raw || srv_start_raw_disk_in_use);

	node->is_raw_disk = is_raw;

	node->size = size;

	node->magic_n = FIL_NODE_MAGIC_N;

	node->init_size = size;
	node->max_size = max_pages;

	node->space = this;

	node->atomic_write = atomic_write;

	mutex_enter(&fil_system.mutex);
	this->size += size;
	UT_LIST_ADD_LAST(chain, node);
	if (node->is_open()) {
		fil_system.n_open++;
	}
	mutex_exit(&fil_system.mutex);

	return node;
}

/** Open a file node of a tablespace.
@param[in,out]	node	File node
@return false if the file can't be opened, otherwise true */
static bool fil_node_open_file(fil_node_t* node)
{
	bool		success;
	bool		read_only_mode;
	fil_space_t*	space = node->space;

	ut_ad(mutex_own(&fil_system.mutex));
	ut_a(node->n_pending == 0);
	ut_a(!node->is_open());

	read_only_mode = space->purpose != FIL_TYPE_TEMPORARY
		&& srv_read_only_mode;

	const bool first_time_open = node->size == 0;

	if (first_time_open
	    || (space->purpose == FIL_TYPE_TABLESPACE
		&& node == UT_LIST_GET_FIRST(space->chain)
		&& srv_startup_is_before_trx_rollback_phase)) {
		/* We do not know the size of the file yet. First we
		open the file in the normal mode, no async I/O here,
		for simplicity. Then do some checks, and close the
		file again.  NOTE that we could not use the simple
		file read function os_file_read() in Windows to read
		from a file opened for async I/O! */

retry:
		node->handle = os_file_create(
			innodb_data_file_key, node->name,
			node->is_raw_disk
			? OS_FILE_OPEN_RAW | OS_FILE_ON_ERROR_NO_EXIT
			: OS_FILE_OPEN | OS_FILE_ON_ERROR_NO_EXIT,
			OS_FILE_AIO, OS_DATA_FILE, read_only_mode, &success);

		if (!success) {
			/* The following call prints an error message */
			ulint err = os_file_get_last_error(true);
			if (err == EMFILE + 100) {
				if (fil_try_to_close_file_in_LRU(true))
					goto retry;
			}

			ib::warn() << "Cannot open '" << node->name << "'."
				" Have you deleted .ibd files under a"
				" running mysqld server?";
			return(false);
		}

		if (!node->read_page0(first_time_open)) {
fail:
			os_file_close(node->handle);
			node->handle = OS_FILE_CLOSED;
			return false;
		}

		if (first_time_open && !fil_comp_algo_validate(space)) {
			goto fail;
		}

	} else {
		node->handle = os_file_create(
			innodb_data_file_key, node->name,
			node->is_raw_disk
			? OS_FILE_OPEN_RAW | OS_FILE_ON_ERROR_NO_EXIT
			: OS_FILE_OPEN | OS_FILE_ON_ERROR_NO_EXIT,
			OS_FILE_AIO, OS_DATA_FILE, read_only_mode, &success);
	}

	ut_a(success);
	ut_a(node->is_open());

	fil_system.n_open++;

	if (fil_space_belongs_in_lru(space)) {

		/* Put the node to the LRU list */
		UT_LIST_ADD_FIRST(fil_system.LRU, node);
	}

	return(true);
}

/** Close the file handle. */
void fil_node_t::close()
{
	bool	ret;

	ut_ad(mutex_own(&fil_system.mutex));
	ut_a(is_open());
	ut_a(n_pending == 0);
	ut_a(n_pending_flushes == 0);
	ut_a(!being_extended);
	ut_a(!needs_flush
	     || space->purpose == FIL_TYPE_TEMPORARY
	     || srv_fast_shutdown == 2
	     || !srv_was_started);

	ret = os_file_close(handle);
	ut_a(ret);

	/* printf("Closing file %s\n", name); */

	handle = OS_FILE_CLOSED;
	ut_ad(!is_open());
	ut_a(fil_system.n_open > 0);
	fil_system.n_open--;

	if (fil_space_belongs_in_lru(space)) {
		ut_a(UT_LIST_GET_LEN(fil_system.LRU) > 0);
		UT_LIST_REMOVE(fil_system.LRU, this);
	}
}

/** Tries to close a file in the LRU list. The caller must hold the fil_sys
mutex.
@return true if success, false if should retry later; since i/o's
generally complete in < 100 ms, and as InnoDB writes at most 128 pages
from the buffer pool in a batch, and then immediately flushes the
files, there is a good chance that the next time we find a suitable
node from the LRU list.
@param[in] print_info	if true, prints information why it
			cannot close a file*/
static
bool
fil_try_to_close_file_in_LRU(

	bool	print_info)
{
	fil_node_t*	node;

	ut_ad(mutex_own(&fil_system.mutex));

	if (print_info) {
		ib::info() << "fil_sys open file LRU len "
			<< UT_LIST_GET_LEN(fil_system.LRU);
	}

	for (node = UT_LIST_GET_LAST(fil_system.LRU);
	     node != NULL;
	     node = UT_LIST_GET_PREV(LRU, node)) {

		if (!node->needs_flush
		    && node->n_pending_flushes == 0
		    && !node->being_extended) {

			node->close();

			return(true);
		}

		if (!print_info) {
			continue;
		}

		if (node->n_pending_flushes > 0) {

			ib::info() << "Cannot close file " << node->name
				<< ", because n_pending_flushes "
				<< node->n_pending_flushes;
		}

		if (node->needs_flush) {
			ib::warn() << "Cannot close file " << node->name
				<< ", because is should be flushed first";
		}

		if (node->being_extended) {
			ib::info() << "Cannot close file " << node->name
				<< ", because it is being extended";
		}
	}

	return(false);
}

/** Flush any writes cached by the file system.
@param[in,out]	space		tablespace
@param[in]	metadata	whether to update file system metadata */
static void fil_flush_low(fil_space_t* space, bool metadata = false)
{
	ut_ad(mutex_own(&fil_system.mutex));
	ut_ad(space);
	ut_ad(!space->stop_new_ops);

	if (srv_file_flush_method == SRV_O_DIRECT_NO_FSYNC) {
		/* No need to flush. User has explicitly disabled
		buffering. */
		ut_ad(!space->is_in_unflushed_spaces);
		ut_ad(fil_space_is_flushed(space));
		ut_ad(space->n_pending_flushes == 0);

#ifdef UNIV_DEBUG
		for (fil_node_t* node = UT_LIST_GET_FIRST(space->chain);
		     node != NULL;
		     node = UT_LIST_GET_NEXT(chain, node)) {
			ut_ad(!node->needs_flush);
			ut_ad(node->n_pending_flushes == 0);
		}
#endif /* UNIV_DEBUG */

		if (!metadata) return;
	}

	/* Prevent dropping of the space while we are flushing */
	space->n_pending_flushes++;

	for (fil_node_t* node = UT_LIST_GET_FIRST(space->chain);
	     node != NULL;
	     node = UT_LIST_GET_NEXT(chain, node)) {

		if (!node->needs_flush) {
			continue;
		}

		ut_a(node->is_open());

		fil_n_pending_tablespace_flushes++;

#ifdef _WIN32
		if (node->is_raw_disk) {

			goto skip_flush;
		}
#endif /* _WIN32 */

		ut_a(node->is_open());
		node->n_pending_flushes++;
		node->needs_flush = false;

		mutex_exit(&fil_system.mutex);

		os_file_flush(node->handle);

		mutex_enter(&fil_system.mutex);

		node->n_pending_flushes--;
#ifdef _WIN32
skip_flush:
#endif /* _WIN32 */
		if (!node->needs_flush) {
			if (space->is_in_unflushed_spaces
			    && fil_space_is_flushed(space)) {

				fil_system.unflushed_spaces.remove(*space);
				space->is_in_unflushed_spaces = false;
			}
		}

		fil_n_pending_tablespace_flushes--;
	}

	space->n_pending_flushes--;
}

/** Try to extend a tablespace.
@param[in,out]	space	tablespace to be extended
@param[in,out]	node	last file of the tablespace
@param[in]	size	desired size in number of pages
@param[out]	success	whether the operation succeeded
@return	whether the operation should be retried */
static ATTRIBUTE_COLD __attribute__((warn_unused_result, nonnull))
bool
fil_space_extend_must_retry(
	fil_space_t*	space,
	fil_node_t*	node,
	ulint		size,
	bool*		success)
{
	ut_ad(mutex_own(&fil_system.mutex));
	ut_ad(UT_LIST_GET_LAST(space->chain) == node);
	ut_ad(size >= FIL_IBD_FILE_INITIAL_SIZE);

	*success = space->size >= size;

	if (*success) {
		/* Space already big enough */
		return(false);
	}

	if (node->being_extended) {
		/* Another thread is currently extending the file. Wait
		for it to finish.
		It'd have been better to use event driven mechanism but
		the entire module is peppered with polling stuff. */
		mutex_exit(&fil_system.mutex);
		os_thread_sleep(100000);
		return(true);
	}

	node->being_extended = true;

	if (!fil_node_prepare_for_io(node, space)) {
		/* The tablespace data file, such as .ibd file, is missing */
		node->being_extended = false;
		return(false);
	}

	/* At this point it is safe to release fil_system.mutex. No
	other thread can rename, delete, close or extend the file because
	we have set the node->being_extended flag. */
	mutex_exit(&fil_system.mutex);

	ut_ad(size >= space->size);

	ulint		last_page_no		= space->size;
	const ulint	file_start_page_no	= last_page_no - node->size;

	const ulint	page_size = space->physical_size();

	/* fil_read_first_page() expects srv_page_size bytes.
	fil_node_open_file() expects at least 4 * srv_page_size bytes.*/
	os_offset_t new_size = std::max(
		os_offset_t(size - file_start_page_no) * page_size,
		os_offset_t(FIL_IBD_FILE_INITIAL_SIZE << srv_page_size_shift));

	*success = os_file_set_size(node->name, node->handle, new_size,
		FSP_FLAGS_HAS_PAGE_COMPRESSION(space->flags));

	os_has_said_disk_full = *success;
	if (*success) {
		os_file_flush(node->handle);
		last_page_no = size;
	} else {
		/* Let us measure the size of the file
		to determine how much we were able to
		extend it */
		os_offset_t	fsize = os_file_get_size(node->handle);
		ut_a(fsize != os_offset_t(-1));

		last_page_no = ulint(fsize / page_size)
			+ file_start_page_no;
	}
	mutex_enter(&fil_system.mutex);

	ut_a(node->being_extended);
	node->being_extended = false;
	ut_a(last_page_no - file_start_page_no >= node->size);

	ulint file_size = last_page_no - file_start_page_no;
	space->size += file_size - node->size;
	node->size = file_size;
	const ulint pages_in_MiB = node->size
		& ~ulint((1U << (20U - srv_page_size_shift)) - 1);

	node->complete_io();

	/* Keep the last data file size info up to date, rounded to
	full megabytes */

	switch (space->id) {
	case TRX_SYS_SPACE:
		srv_sys_space.set_last_file_size(pages_in_MiB);
		fil_flush_low(space, true);
		return(false);
	default:
		ut_ad(space->purpose == FIL_TYPE_TABLESPACE
		      || space->purpose == FIL_TYPE_IMPORT);
		if (space->purpose == FIL_TYPE_TABLESPACE
		    && !space->is_being_truncated) {
			fil_flush_low(space, true);
		}
		return(false);
	case SRV_TMP_SPACE_ID:
		ut_ad(space->purpose == FIL_TYPE_TEMPORARY);
		srv_tmp_space.set_last_file_size(pages_in_MiB);
		return(false);
	}
}

/** Acquire fil_system.mutex and try to make sure we can open at least one
file while holding it. This should be called before calling
fil_node_prepare_for_io(), because that function may need to open a file. */
static
fil_space_t*
fil_mutex_enter_and_prepare_for_io(
	ulint	space_id)	/*!< in: space id */
{
	for (ulint count = 0;;) {
		mutex_enter(&fil_system.mutex);

		fil_space_t*	space = fil_space_get_by_id(space_id);

		if (!space) {
			return nullptr;
		}

		fil_node_t*	node = UT_LIST_GET_LAST(space->chain);
		ut_ad(space->id == 0
		      || node == UT_LIST_GET_FIRST(space->chain));

		if (space->id == 0) {
			/* We keep the system tablespace files always
			open; this is important in preventing
			deadlocks in this module, as a page read
			completion often performs another read from
			the insert buffer. The insert buffer is in
			tablespace 0, and we cannot end up waiting in
			this function. */
		} else if (!node || node->is_open()) {
			/* If the file is already open, no need to do
			anything; if the space does not exist, we handle the
			situation in the function which called this
			function */
		} else {
			while (fil_system.n_open >= srv_max_n_open_files) {
				/* Too many files are open */
				if (fil_try_to_close_file_in_LRU(count > 1)) {
					/* No problem */
				} else if (count >= 2) {
					ib::warn() << "innodb_open_files="
						<< srv_max_n_open_files
						<< " is exceeded ("
						<< fil_system.n_open
						<< ") files stay open)";
					break;
				} else {
					mutex_exit(&fil_system.mutex);
					os_thread_sleep(20000);
					/* Flush tablespaces so that we can
					close modified files in the LRU list */
					fil_flush_file_spaces();

					count++;
					mutex_enter(&fil_system.mutex);
					continue;
				}
			}
		}

		ulint size = space->recv_size;
		if (UNIV_UNLIKELY(size != 0)) {
			ut_ad(node);
			bool	success;
			if (fil_space_extend_must_retry(space, node, size,
							&success)) {
				continue;
			}

			ut_ad(mutex_own(&fil_system.mutex));
			/* Crash recovery requires the file extension
			to succeed. */
			ut_a(success);
			/* InnoDB data files cannot shrink. */
			ut_a(space->size >= size);

			/* There could be multiple concurrent I/O requests for
			this tablespace (multiple threads trying to extend
			this tablespace).

			Also, fil_space_set_recv_size() may have been invoked
			again during the file extension while fil_system.mutex
			was not being held by us.

			Only if space->recv_size matches what we read
			originally, reset the field. In this way, a
			subsequent I/O request will handle any pending
			fil_space_set_recv_size(). */

			if (size == space->recv_size) {
				space->recv_size = 0;
			}
		}

		return space;
	}
}

/** Try to extend a tablespace if it is smaller than the specified size.
@param[in,out]	space	tablespace
@param[in]	size	desired size in pages
@return whether the tablespace is at least as big as requested */
bool
fil_space_extend(
	fil_space_t*	space,
	ulint		size)
{
	ut_ad(!srv_read_only_mode || space->purpose == FIL_TYPE_TEMPORARY);

	bool	success;

	do {
		fil_mutex_enter_and_prepare_for_io(space->id);
	} while (fil_space_extend_must_retry(
			 space, UT_LIST_GET_LAST(space->chain), size,
			 &success));

	mutex_exit(&fil_system.mutex);
	return(success);
}

/** Prepare to free a file from fil_system. */
inline void fil_node_t::close_to_free()
{
  ut_ad(mutex_own(&fil_system.mutex));
  ut_a(magic_n == FIL_NODE_MAGIC_N);
  ut_a(!being_extended);

  while (is_open())
  {
    if (space->is_in_unflushed_spaces)
    {
      ut_ad(srv_file_flush_method != SRV_O_DIRECT_NO_FSYNC);
      space->is_in_unflushed_spaces= false;
      fil_system.unflushed_spaces.remove(*space);
    }

    if (n_pending)
    {
      mutex_exit(&fil_system.mutex);
      os_thread_sleep(100);
      mutex_enter(&fil_system.mutex);
      continue;
    }

    if (srv_file_flush_method == SRV_O_DIRECT_NO_FSYNC)
    {
      ut_ad(!space->is_in_unflushed_spaces);
      ut_ad(fil_space_is_flushed(space));
    }
    else if (space->is_in_unflushed_spaces && fil_space_is_flushed(space))
    {
      space->is_in_unflushed_spaces= false;
      fil_system.unflushed_spaces.remove(*space);
    }

    if (fil_space_belongs_in_lru(space))
    {
      ut_ad(UT_LIST_GET_LEN(fil_system.LRU) > 0);
      UT_LIST_REMOVE(fil_system.LRU, this);
    }
    ut_a(!n_pending_flushes);
    ut_a(!being_extended);
    bool ret= os_file_close(handle);
    ut_a(ret);
    handle= OS_FILE_CLOSED;
    break;
  }
}

/** Detach a tablespace from the cache and close the files. */
inline void fil_system_t::detach(fil_space_t *space)
{
  ut_ad(mutex_own(&fil_system.mutex));
  HASH_DELETE(fil_space_t, hash, spaces, space->id, space);

  if (space->is_in_unflushed_spaces)
  {
    ut_ad(srv_file_flush_method != SRV_O_DIRECT_NO_FSYNC);
    space->is_in_unflushed_spaces= false;
    unflushed_spaces.remove(*space);
  }

  if (space->is_in_rotation_list)
  {
    space->is_in_rotation_list= false;
    rotation_list.remove(*space);
  }
  UT_LIST_REMOVE(space_list, space);
  if (space == sys_space)
    sys_space= nullptr;
  else if (space == temp_space)
    temp_space= nullptr;

  ut_a(space->magic_n == FIL_SPACE_MAGIC_N);
  ut_a(space->n_pending_flushes == 0);

  for (fil_node_t* node= UT_LIST_GET_FIRST(space->chain); node;
       node= UT_LIST_GET_NEXT(chain, node))
    if (node->is_open())
    {
      ut_ad(n_open > 0);
      n_open--;
    }

  for (fil_node_t* node= UT_LIST_GET_FIRST(space->chain); node;
       node= UT_LIST_GET_NEXT(chain, node))
    node->close_to_free();
}

/** Free a tablespace object on which fil_system_t::detach() was invoked.
There must not be any pending i/o's or flushes on the files.
@param[in,out]	space		tablespace */
static
void
fil_space_free_low(
	fil_space_t*	space)
{
	/* The tablespace must not be in fil_system.named_spaces. */
	ut_ad(srv_fast_shutdown == 2 || !srv_was_started
	      || space->max_lsn == 0);

	/* Wait for fil_space_t::release_for_io(); after
	fil_system_t::detach(), the tablespace cannot be found, so
	fil_space_acquire_for_io() would return NULL */
	while (space->pending_io()) {
		os_thread_sleep(100);
	}

	for (fil_node_t* node = UT_LIST_GET_FIRST(space->chain);
	     node != NULL; ) {
		ut_d(space->size -= node->size);
		ut_free(node->name);
		fil_node_t* old_node = node;
		node = UT_LIST_GET_NEXT(chain, node);
		ut_free(old_node);
	}

	ut_ad(space->size == 0);

	rw_lock_free(&space->latch);
	fil_space_destroy_crypt_data(&space->crypt_data);

	ut_free(space->name);
	ut_free(space);
}

/** Frees a space object from the tablespace memory cache.
Closes the files in the chain but does not delete them.
There must not be any pending i/o's or flushes on the files.
@param[in]	id		tablespace identifier
@param[in]	x_latched	whether the caller holds X-mode space->latch
@return true if success */
bool
fil_space_free(
	ulint		id,
	bool		x_latched)
{
	ut_ad(id != TRX_SYS_SPACE);

	mutex_enter(&fil_system.mutex);
	fil_space_t*	space = fil_space_get_by_id(id);

	if (space != NULL) {
		fil_system.detach(space);
	}

	mutex_exit(&fil_system.mutex);

	if (space != NULL) {
		if (x_latched) {
			rw_lock_x_unlock(&space->latch);
		}

		if (!recv_recovery_is_on()) {
			log_mutex_enter();
		}

		ut_ad(log_mutex_own());

		if (space->max_lsn != 0) {
			ut_d(space->max_lsn = 0);
			UT_LIST_REMOVE(fil_system.named_spaces, space);
		}

		if (!recv_recovery_is_on()) {
			log_mutex_exit();
		}

		fil_space_free_low(space);
	}

	return(space != NULL);
}

/** Create a space memory object and put it to the fil_system hash table.
Error messages are issued to the server log.
@param[in]	name		tablespace name
@param[in]	id		tablespace identifier
@param[in]	flags		tablespace flags
@param[in]	purpose		tablespace purpose
@param[in,out]	crypt_data	encryption information
@param[in]	mode		encryption mode
@return pointer to created tablespace, to be filled in with fil_space_t::add()
@retval NULL on failure (such as when the same tablespace exists) */
fil_space_t*
fil_space_create(
	const char*		name,
	ulint			id,
	ulint			flags,
	fil_type_t		purpose,
	fil_space_crypt_t*	crypt_data,
	fil_encryption_t	mode)
{
	fil_space_t*	space;

	ut_ad(fil_system.is_initialised());
	ut_ad(fil_space_t::is_valid_flags(flags & ~FSP_FLAGS_MEM_MASK, id));
	ut_ad(srv_page_size == UNIV_PAGE_SIZE_ORIG || flags != 0);

	DBUG_EXECUTE_IF("fil_space_create_failure", return(NULL););

	mutex_enter(&fil_system.mutex);

	space = fil_space_get_by_id(id);

	if (space != NULL) {
		ib::error() << "Trying to add tablespace '" << name
			<< "' with id " << id
			<< " to the tablespace memory cache, but tablespace '"
			<< space->name << "' already exists in the cache!";
		mutex_exit(&fil_system.mutex);
		return(NULL);
	}

	space = static_cast<fil_space_t*>(ut_zalloc_nokey(sizeof(*space)));

	space->id = id;
	space->name = mem_strdup(name);

	UT_LIST_INIT(space->chain, &fil_node_t::chain);

	if ((purpose == FIL_TYPE_TABLESPACE || purpose == FIL_TYPE_IMPORT)
	    && !recv_recovery_is_on()
	    && id > fil_system.max_assigned_id) {
		if (!fil_system.space_id_reuse_warned) {
			fil_system.space_id_reuse_warned = true;

			ib::warn() << "Allocated tablespace ID " << id
				<< " for " << name << ", old maximum was "
				<< fil_system.max_assigned_id;
		}

		fil_system.max_assigned_id = id;
	}

	space->purpose = purpose;
	space->flags = flags;

	space->magic_n = FIL_SPACE_MAGIC_N;
	space->crypt_data = crypt_data;

	DBUG_LOG("tablespace",
		 "Created metadata for " << id << " name " << name);
	if (crypt_data) {
		DBUG_LOG("crypt",
			 "Tablespace " << id << " name " << name
			 << " encryption " << crypt_data->encryption
			 << " key id " << crypt_data->key_id
			 << ":" << fil_crypt_get_mode(crypt_data)
			 << " " << fil_crypt_get_type(crypt_data));
	}

	rw_lock_create(fil_space_latch_key, &space->latch, SYNC_FSP);

	if (space->purpose == FIL_TYPE_TEMPORARY) {
		/* SysTablespace::open_or_create() would pass
		size!=0 to fil_space_t::add(), so first_time_open
		would not hold in fil_node_open_file(), and we
		must assign this manually. We do not care about
		the durability or atomicity of writes to the
		temporary tablespace files. */
		space->atomic_write_supported = true;
	}

	HASH_INSERT(fil_space_t, hash, fil_system.spaces, id, space);

	UT_LIST_ADD_LAST(fil_system.space_list, space);

	if (id < SRV_SPACE_ID_UPPER_BOUND && id > fil_system.max_assigned_id) {

		fil_system.max_assigned_id = id;
	}

	/* Inform key rotation that there could be something
	to do */
	if (purpose == FIL_TYPE_TABLESPACE
	    && !srv_fil_crypt_rotate_key_age && fil_crypt_threads_event &&
	    (mode == FIL_ENCRYPTION_ON || mode == FIL_ENCRYPTION_OFF
	     || srv_encrypt_tables)) {
		/* Key rotation is not enabled, need to inform background
		encryption threads. */
		fil_system.rotation_list.push_back(*space);
		space->is_in_rotation_list = true;
		mutex_exit(&fil_system.mutex);
		os_event_set(fil_crypt_threads_event);
	} else {
		mutex_exit(&fil_system.mutex);
	}

	return(space);
}

/*******************************************************************//**
Assigns a new space id for a new single-table tablespace. This works simply by
incrementing the global counter. If 4 billion id's is not enough, we may need
to recycle id's.
@return true if assigned, false if not */
bool
fil_assign_new_space_id(
/*====================*/
	ulint*	space_id)	/*!< in/out: space id */
{
	ulint	id;
	bool	success;

	mutex_enter(&fil_system.mutex);

	id = *space_id;

	if (id < fil_system.max_assigned_id) {
		id = fil_system.max_assigned_id;
	}

	id++;

	if (id > (SRV_SPACE_ID_UPPER_BOUND / 2) && (id % 1000000UL == 0)) {
		ib::warn() << "You are running out of new single-table"
			" tablespace id's. Current counter is " << id
			<< " and it must not exceed" <<SRV_SPACE_ID_UPPER_BOUND
			<< "! To reset the counter to zero you have to dump"
			" all your tables and recreate the whole InnoDB"
			" installation.";
	}

	success = (id < SRV_SPACE_ID_UPPER_BOUND);

	if (success) {
		*space_id = fil_system.max_assigned_id = id;
	} else {
		ib::warn() << "You have run out of single-table tablespace"
			" id's! Current counter is " << id
			<< ". To reset the counter to zero"
			" you have to dump all your tables and"
			" recreate the whole InnoDB installation.";
		*space_id = ULINT_UNDEFINED;
	}

	mutex_exit(&fil_system.mutex);

	return(success);
}

/** Trigger a call to fil_node_t::read_page0()
@param[in]	id	tablespace identifier
@return	tablespace
@retval	NULL	if the tablespace does not exist or cannot be read */
fil_space_t* fil_system_t::read_page0(ulint id)
{
	mutex_exit(&mutex);

	ut_ad(id != 0);

	/* It is possible that the tablespace is dropped while we are
	not holding the mutex. */
	fil_space_t* space = fil_mutex_enter_and_prepare_for_io(id);

	if (space == NULL || UT_LIST_GET_LEN(space->chain) == 0) {
		return(NULL);
	}

	/* The following code must change when InnoDB supports
	multiple datafiles per tablespace. */
	ut_a(1 == UT_LIST_GET_LEN(space->chain));

	fil_node_t* node = UT_LIST_GET_FIRST(space->chain);

	/* It must be a single-table tablespace and we have not opened
	the file yet; the following calls will open it and update the
	size fields */

	if (!fil_node_prepare_for_io(node, space)) {
		/* The single-table tablespace can't be opened,
		because the ibd file is missing. */
		return(NULL);
	}

	node->complete_io();

	return space;
}

/*******************************************************************//**
Returns a pointer to the fil_space_t that is in the memory cache
associated with a space id. The caller must lock fil_system.mutex.
@return file_space_t pointer, NULL if space not found */
UNIV_INLINE
fil_space_t*
fil_space_get_space(
/*================*/
	ulint	id)	/*!< in: space id */
{
	fil_space_t* space = fil_space_get_by_id(id);
	if (space == NULL || space->size != 0) {
		return(space);
	}

	space = fil_system.read_page0(id);
	return(space);
}

/** Set the recovered size of a tablespace in pages.
@param id	tablespace ID
@param size	recovered size in pages */
UNIV_INTERN
void
fil_space_set_recv_size(ulint id, ulint size)
{
	mutex_enter(&fil_system.mutex);
	ut_ad(size);
	ut_ad(id < SRV_SPACE_ID_UPPER_BOUND);

	if (fil_space_t* space = fil_space_get_space(id)) {
		space->recv_size = size;
	}

	mutex_exit(&fil_system.mutex);
}

/*******************************************************************//**
Returns the size of the space in pages. The tablespace must be cached in the
memory cache.
@return space size, 0 if space not found */
ulint
fil_space_get_size(
/*===============*/
	ulint	id)	/*!< in: space id */
{
	fil_space_t*	space;
	ulint		size;

	ut_ad(fil_system.is_initialised());
	mutex_enter(&fil_system.mutex);

	space = fil_space_get_space(id);

	size = space ? space->size : 0;

	mutex_exit(&fil_system.mutex);

	return(size);
}

/** Open each file. Only invoked on fil_system.temp_space.
@return whether all files were opened */
bool fil_space_t::open()
{
	ut_ad(fil_system.is_initialised());

	mutex_enter(&fil_system.mutex);
	ut_ad(this == fil_system.temp_space
	      || srv_operation == SRV_OPERATION_BACKUP
	      || srv_operation == SRV_OPERATION_RESTORE
	      || srv_operation == SRV_OPERATION_RESTORE_DELTA);

	for (fil_node_t* node = UT_LIST_GET_FIRST(chain);
	     node != NULL;
	     node = UT_LIST_GET_NEXT(chain, node)) {
		if (!node->is_open() && !fil_node_open_file(node)) {
			mutex_exit(&fil_system.mutex);
			return false;
		}
	}

	mutex_exit(&fil_system.mutex);
	return true;
}

/** Close each file. Only invoked on fil_system.temp_space. */
void fil_space_t::close()
{
	if (!fil_system.is_initialised()) {
		return;
	}

	mutex_enter(&fil_system.mutex);
	ut_ad(this == fil_system.temp_space
	      || srv_operation == SRV_OPERATION_BACKUP
	      || srv_operation == SRV_OPERATION_RESTORE
	      || srv_operation == SRV_OPERATION_RESTORE_DELTA);

	for (fil_node_t* node = UT_LIST_GET_FIRST(chain);
	     node != NULL;
	     node = UT_LIST_GET_NEXT(chain, node)) {
		if (node->is_open()) {
			node->close();
		}
	}

	mutex_exit(&fil_system.mutex);
}

void fil_system_t::create(ulint hash_size)
{
	ut_ad(this == &fil_system);
	ut_ad(!is_initialised());
	ut_ad(!(srv_page_size % FSP_EXTENT_SIZE));
	ut_ad(srv_page_size);
	ut_ad(!spaces);

	m_initialised = true;

	compile_time_assert(!(UNIV_PAGE_SIZE_MAX % FSP_EXTENT_SIZE_MAX));
	compile_time_assert(!(UNIV_PAGE_SIZE_MIN % FSP_EXTENT_SIZE_MIN));

	ut_ad(hash_size > 0);

	mutex_create(LATCH_ID_FIL_SYSTEM, &mutex);

	spaces = hash_create(hash_size);

	fil_space_crypt_init();
#ifdef UNIV_LINUX
	ssd.clear();
	char fn[sizeof(dirent::d_name)
		+ sizeof "/sys/block/" "/queue/rotational"];
	const size_t sizeof_fnp = (sizeof fn) - sizeof "/sys/block";
	memcpy(fn, "/sys/block/", sizeof "/sys/block");
	char* fnp = &fn[sizeof "/sys/block"];

	std::set<std::string> ssd_devices;
	if (DIR* d = opendir("/sys/block")) {
		while (struct dirent* e = readdir(d)) {
			if (e->d_name[0] == '.') {
				continue;
			}
			snprintf(fnp, sizeof_fnp, "%s/queue/rotational",
				 e->d_name);
			int f = open(fn, O_RDONLY);
			if (f == -1) {
				continue;
			}
			char b[sizeof "4294967295:4294967295\n"];
			ssize_t l = read(f, b, sizeof b);
			::close(f);
			if (l != 2 || memcmp("0\n", b, 2)) {
				continue;
			}
			snprintf(fnp, sizeof_fnp, "%s/dev", e->d_name);
			f = open(fn, O_RDONLY);
			if (f == -1) {
				continue;
			}
			l = read(f, b, sizeof b);
			::close(f);
			if (l <= 0 || b[l - 1] != '\n') {
				continue;
			}
			b[l - 1] = '\0';
			char* end = b;
			unsigned long dev_major = strtoul(b, &end, 10);
			if (b == end || *end != ':'
			    || dev_major != unsigned(dev_major)) {
				continue;
			}
			char* c = end + 1;
			unsigned long dev_minor = strtoul(c, &end, 10);
			if (c == end || *end
			    || dev_minor != unsigned(dev_minor)) {
				continue;
			}
			ssd.push_back(makedev(unsigned(dev_major),
					      unsigned(dev_minor)));
		}
		closedir(d);
	}
	/* fil_system_t::is_ssd() assumes the following */
	ut_ad(makedev(0, 8) == 8);
	ut_ad(makedev(0, 4) == 4);
	ut_ad(makedev(0, 2) == 2);
	ut_ad(makedev(0, 1) == 1);
#endif
}

void fil_system_t::close()
{
	ut_ad(this == &fil_system);
	ut_a(!UT_LIST_GET_LEN(LRU));
	ut_a(unflushed_spaces.empty());
	ut_a(!UT_LIST_GET_LEN(space_list));
	ut_ad(!sys_space);
	ut_ad(!temp_space);

	if (is_initialised()) {
		m_initialised = false;
		hash_table_free(spaces);
		spaces = NULL;
		mutex_free(&mutex);
		fil_space_crypt_cleanup();
	}

	ut_ad(!spaces);
}

/** Opens all system tablespace data files. They stay open until the
database server shutdown. This should be called at a server startup after the
space objects for the system tablespace have been created. The
purpose of this operation is to make sure we never run out of file descriptors
if we need to read from the insert buffer. */
void
fil_open_system_tablespace_files()
{
	fil_space_t*	space;

	mutex_enter(&fil_system.mutex);

	for (space = UT_LIST_GET_FIRST(fil_system.space_list);
	     space != NULL;
	     space = UT_LIST_GET_NEXT(space_list, space)) {

		fil_node_t*	node;

		if (fil_space_belongs_in_lru(space)) {

			continue;
		}

		for (node = UT_LIST_GET_FIRST(space->chain);
		     node != NULL;
		     node = UT_LIST_GET_NEXT(chain, node)) {

			if (!node->is_open()) {
				if (!fil_node_open_file(node)) {
					/* This func is called during server's
					startup. If some file of log or system
					tablespace is missing, the server
					can't start successfully. So we should
					assert for it. */
					ut_a(0);
				}
			}

			if (srv_max_n_open_files < 10 + fil_system.n_open) {

				ib::warn() << "You must raise the value of"
					" innodb_open_files in my.cnf!"
					" Remember that InnoDB keeps all"
					" log files and all system"
					" tablespace files open"
					" for the whole time mysqld is"
					" running, and needs to open also"
					" some .ibd files if the"
					" file-per-table storage model is used."
					" Current open files "
					<< fil_system.n_open
					<< ", max allowed open files "
					<< srv_max_n_open_files
					<< ".";
			}
		}
	}

	mutex_exit(&fil_system.mutex);
}

/** Close all tablespace files at shutdown */
void fil_close_all_files()
{
	if (!fil_system.is_initialised()) {
		return;
	}

	fil_space_t*	space;

	/* At shutdown, we should not have any files in this list. */
	ut_ad(srv_fast_shutdown == 2
	      || !srv_was_started
	      || UT_LIST_GET_LEN(fil_system.named_spaces) == 0);
	fil_flush_file_spaces();

	mutex_enter(&fil_system.mutex);

	for (space = UT_LIST_GET_FIRST(fil_system.space_list); space; ) {
		fil_node_t*	node;
		fil_space_t*	prev_space = space;

		for (node = UT_LIST_GET_FIRST(space->chain);
		     node != NULL;
		     node = UT_LIST_GET_NEXT(chain, node)) {

			if (!node->is_open()) {
next:
				continue;
			}

			for (ulint count = 10000; count--; ) {
				mutex_exit(&fil_system.mutex);
				os_thread_sleep(100);
				mutex_enter(&fil_system.mutex);
				if (!node->is_open()) {
					goto next;
				}
				if (!node->n_pending) {
					node->close();
					goto next;
				}
			}

			ib::error() << "File '" << node->name
				    << "' has " << node->n_pending
				    << " operations";
		}

		space = UT_LIST_GET_NEXT(space_list, space);
		fil_system.detach(prev_space);
		fil_space_free_low(prev_space);
	}

	mutex_exit(&fil_system.mutex);

	ut_ad(srv_fast_shutdown == 2
	      || !srv_was_started
	      || UT_LIST_GET_LEN(fil_system.named_spaces) == 0);
}

/*******************************************************************//**
Sets the max tablespace id counter if the given number is bigger than the
previous value. */
void
fil_set_max_space_id_if_bigger(
/*===========================*/
	ulint	max_id)	/*!< in: maximum known id */
{
	if (max_id >= SRV_SPACE_ID_UPPER_BOUND) {
		ib::fatal() << "Max tablespace id is too high, " << max_id;
	}

	mutex_enter(&fil_system.mutex);

	if (fil_system.max_assigned_id < max_id) {

		fil_system.max_assigned_id = max_id;
	}

	mutex_exit(&fil_system.mutex);
}

/** Write the flushed LSN to the page header of the first page in the
system tablespace.
@param[in]	lsn	flushed LSN
@return DB_SUCCESS or error number */
dberr_t
fil_write_flushed_lsn(
	lsn_t	lsn)
{
	byte*	buf;
	ut_ad(!srv_read_only_mode);

	buf = static_cast<byte*>(aligned_malloc(srv_page_size, srv_page_size));

	const page_id_t	page_id(TRX_SYS_SPACE, 0);

	fil_io_t fio = fil_io(IORequestRead, true, page_id, 0, 0,
			      srv_page_size, buf, NULL);

	if (fio.err == DB_SUCCESS) {
		fio.node->space->release_for_io();
		mach_write_to_8(buf + FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION, lsn);

		ulint fsp_flags = mach_read_from_4(
			buf + FSP_HEADER_OFFSET + FSP_SPACE_FLAGS);

		if (fil_space_t::full_crc32(fsp_flags)) {
			buf_flush_assign_full_crc32_checksum(buf);
		}

		fio = fil_io(IORequestWrite, true, page_id, 0, 0,
			     srv_page_size, buf, NULL);
		fil_flush_file_spaces();
	}

	if (fio.node) {
		fio.node->space->release_for_io();
	}

	aligned_free(buf);
	return fio.err;
}

/** Acquire a tablespace when it could be dropped concurrently.
Used by background threads that do not necessarily hold proper locks
for concurrency control.
@param[in]	id	tablespace ID
@param[in]	silent	whether to silently ignore missing tablespaces
@return	the tablespace
@retval	NULL if missing or being deleted */
fil_space_t* fil_space_acquire_low(ulint id, bool silent)
{
	fil_space_t*	space;

	mutex_enter(&fil_system.mutex);

	space = fil_space_get_by_id(id);

	if (space == NULL) {
		if (!silent) {
			ib::warn() << "Trying to access missing"
				" tablespace " << id;
		}
	} else if (space->is_stopping()) {
		space = NULL;
	} else {
		space->acquire();
	}

	mutex_exit(&fil_system.mutex);

	return(space);
}

/** Acquire a tablespace for reading or writing a block,
when it could be dropped concurrently.
@param[in]	id	tablespace ID
@return	the tablespace
@retval	NULL if missing */
fil_space_t*
fil_space_acquire_for_io(ulint id)
{
	mutex_enter(&fil_system.mutex);

	fil_space_t* space = fil_space_get_by_id(id);

	if (space) {
		space->acquire_for_io();
	}

	mutex_exit(&fil_system.mutex);

	return(space);
}

/********************************************************//**
Creates the database directory for a table if it does not exist yet. */
void
fil_create_directory_for_tablename(
/*===============================*/
	const char*	name)	/*!< in: name in the standard
				'databasename/tablename' format */
{
	const char*	namend;
	char*		path;
	ulint		len;

	len = strlen(fil_path_to_mysql_datadir);
	namend = strchr(name, '/');
	ut_a(namend);
	path = static_cast<char*>(
		ut_malloc_nokey(len + ulint(namend - name) + 2));

	memcpy(path, fil_path_to_mysql_datadir, len);
	path[len] = '/';
	memcpy(path + len + 1, name, ulint(namend - name));
	path[len + ulint(namend - name) + 1] = 0;

	os_normalize_path(path);

	bool	success = os_file_create_directory(path, false);
	ut_a(success);

	ut_free(path);
}

/** Write a log record about a file operation.
@param type           file operation
@param first_page_no  first page number in the file
@param path           file path
@param new_path       new file path for type=FILE_RENAME */
inline void mtr_t::log_file_op(mfile_type_t type, ulint space_id,
			       const char *path, const char *new_path)
{
  ut_ad((new_path != nullptr) == (type == FILE_RENAME));
  ut_ad(!(byte(type) & 15));

  /* fil_name_parse() requires that there be at least one path
  separator and that the file path end with ".ibd". */
  ut_ad(strchr(path, OS_PATH_SEPARATOR) != NULL);
  ut_ad(!strcmp(&path[strlen(path) - strlen(DOT_IBD)], DOT_IBD));

  flag_modified();
  if (m_log_mode != MTR_LOG_ALL)
    return;
  m_last= nullptr;

  const size_t len= strlen(path);
  const size_t new_len= type == FILE_RENAME ? 1 + strlen(new_path) : 0;
  ut_ad(len > 0);
  byte *const log_ptr= m_log.open(1 + 3/*length*/ + 5/*space_id*/ +
                                  1/*page_no=0*/);
  byte *end= log_ptr + 1;
  end= mlog_encode_varint(end, space_id);
  *end++= 0;
  if (UNIV_LIKELY(end + len + new_len >= &log_ptr[16]))
  {
    *log_ptr= type;
    size_t total_len= len + new_len + end - log_ptr - 15;
    if (total_len >= MIN_3BYTE)
      total_len+= 2;
    else if (total_len >= MIN_2BYTE)
      total_len++;
    end= mlog_encode_varint(log_ptr + 1, total_len);
    end= mlog_encode_varint(end, space_id);
    *end++= 0;
  }
  else
  {
    *log_ptr= static_cast<byte>(type | (end + len + new_len - &log_ptr[1]));
    ut_ad(*log_ptr & 15);
  }

  m_log.close(end);

  if (type == FILE_RENAME)
  {
    ut_ad(strchr(new_path, OS_PATH_SEPARATOR));
    m_log.push(reinterpret_cast<const byte*>(path), uint32_t(len + 1));
    m_log.push(reinterpret_cast<const byte*>(new_path), uint32_t(new_len));
  }
  else
    m_log.push(reinterpret_cast<const byte*>(path), uint32_t(len));
}

/** Write redo log for renaming a file.
@param[in]	space_id	tablespace id
@param[in]	old_name	tablespace file name
@param[in]	new_name	tablespace file name after renaming
@param[in,out]	mtr		mini-transaction */
static
void
fil_name_write_rename_low(
	ulint		space_id,
	const char*	old_name,
	const char*	new_name,
	mtr_t*		mtr)
{
  ut_ad(!is_predefined_tablespace(space_id));
  mtr->log_file_op(FILE_RENAME, space_id, old_name, new_name);
}

/** Write redo log for renaming a file.
@param[in]	space_id	tablespace id
@param[in]	old_name	tablespace file name
@param[in]	new_name	tablespace file name after renaming */
static void
fil_name_write_rename(
	ulint		space_id,
	const char*	old_name,
	const char*	new_name)
{
	mtr_t	mtr;
	mtr.start();
	fil_name_write_rename_low(space_id, old_name, new_name, &mtr);
	mtr.commit();
	log_write_up_to(mtr.commit_lsn(), true);
}

/** Write FILE_MODIFY for a file.
@param[in]	space_id	tablespace id
@param[in]	name		tablespace file name
@param[in,out]	mtr		mini-transaction */
static
void
fil_name_write(
	ulint		space_id,
	const char*	name,
	mtr_t*		mtr)
{
  ut_ad(!is_predefined_tablespace(space_id));
  mtr->log_file_op(FILE_MODIFY, space_id, name);
}

/** Replay a file rename operation if possible.
@param[in]	space_id	tablespace identifier
@param[in]	name		old file name
@param[in]	new_name	new file name
@return	whether the operation was successfully applied
(the name did not exist, or new_name did not exist and
name was successfully renamed to new_name)  */
bool
fil_op_replay_rename(
	ulint		space_id,
	const char*	name,
	const char*	new_name)
{
	/* In order to replay the rename, the following must hold:
	* The new name is not already used.
	* A tablespace exists with the old name.
	* The space ID for that tablepace matches this log entry.
	This will prevent unintended renames during recovery. */
	fil_space_t*	space = fil_space_get(space_id);

	if (space == NULL) {
		return(true);
	}

	const bool name_match
		= strcmp(name, UT_LIST_GET_FIRST(space->chain)->name) == 0;

	if (!name_match) {
		return(true);
	}

	/* Create the database directory for the new name, if
	it does not exist yet */

	const char*	namend = strrchr(new_name, OS_PATH_SEPARATOR);
	ut_a(namend != NULL);

	char*		dir = static_cast<char*>(
		ut_malloc_nokey(ulint(namend - new_name) + 1));

	memcpy(dir, new_name, ulint(namend - new_name));
	dir[namend - new_name] = '\0';

	bool		success = os_file_create_directory(dir, false);
	ut_a(success);

	ulint		dirlen = 0;

	if (const char* dirend = strrchr(dir, OS_PATH_SEPARATOR)) {
		dirlen = ulint(dirend - dir) + 1;
	}

	ut_free(dir);

	/* New path must not exist. */
	dberr_t		err = fil_rename_tablespace_check(
		name, new_name, false);
	if (err != DB_SUCCESS) {
		ib::error() << " Cannot replay file rename."
			" Remove either file and try again.";
		return(false);
	}

	char*		new_table = mem_strdupl(
		new_name + dirlen,
		strlen(new_name + dirlen)
		- 4 /* remove ".ibd" */);

	ut_ad(new_table[ulint(namend - new_name) - dirlen]
	      == OS_PATH_SEPARATOR);
#if OS_PATH_SEPARATOR != '/'
	new_table[namend - new_name - dirlen] = '/';
#endif

	if (!fil_rename_tablespace(
		    space_id, name, new_table, new_name)) {
		ut_error;
	}

	ut_free(new_table);
	return(true);
}

/** Check for pending operations.
@param[in]	space	tablespace
@param[in]	count	number of attempts so far
@return 0 if no operations else count + 1. */
static ulint fil_check_pending_ops(const fil_space_t* space, ulint count)
{
	ut_ad(mutex_own(&fil_system.mutex));

	if (space == NULL) {
		return 0;
	}

	if (ulint n_pending_ops = space->n_pending_ops) {

          /* Give a warning every 10 second, starting after 1 second */
          if ((count % 500) == 50) {
			ib::warn() << "Trying to delete"
				" tablespace '" << space->name
				<< "' but there are " << n_pending_ops
				<< " pending operations on it.";
		}

		return(count + 1);
	}

	return(0);
}

/*******************************************************************//**
Check for pending IO.
@return 0 if no pending else count + 1. */
static
ulint
fil_check_pending_io(
/*=================*/
	fil_space_t*	space,		/*!< in/out: Tablespace to check */
	fil_node_t**	node,		/*!< out: Node in space list */
	ulint		count)		/*!< in: number of attempts so far */
{
	ut_ad(mutex_own(&fil_system.mutex));
	ut_ad(!space->referenced());

	/* The following code must change when InnoDB supports
	multiple datafiles per tablespace. */
	ut_a(UT_LIST_GET_LEN(space->chain) == 1);

	*node = UT_LIST_GET_FIRST(space->chain);

	if (space->n_pending_flushes > 0 || (*node)->n_pending > 0) {

		ut_a(!(*node)->being_extended);

                /* Give a warning every 10 second, starting after 1 second */
		if ((count % 500) == 50) {
			ib::warn() << "Trying to delete"
				" tablespace '" << space->name
				<< "' but there are "
				<< space->n_pending_flushes
				<< " flushes and " << (*node)->n_pending
				<< " pending i/o's on it.";
		}

		return(count + 1);
	}

	return(0);
}

/*******************************************************************//**
Check pending operations on a tablespace.
@return tablespace */
static
fil_space_t*
fil_check_pending_operations(
/*=========================*/
	ulint		id,		/*!< in: space id */
	bool		truncate,	/*!< in: whether to truncate a file */
	char**		path)		/*!< out/own: tablespace path */
{
	ulint		count = 0;

	ut_a(!is_system_tablespace(id));
	mutex_enter(&fil_system.mutex);
	fil_space_t* sp = fil_space_get_by_id(id);

	if (sp) {
		sp->stop_new_ops = true;
		if (sp->crypt_data) {
			sp->acquire();
			mutex_exit(&fil_system.mutex);
			fil_space_crypt_close_tablespace(sp);
			mutex_enter(&fil_system.mutex);
			sp->release();
		}
	}

	/* Check for pending operations. */

	do {
		count = fil_check_pending_ops(sp, count);

		mutex_exit(&fil_system.mutex);

		if (count) {
			os_thread_sleep(20000); // Wait 0.02 seconds
		} else if (!sp) {
			return nullptr;
		}

		mutex_enter(&fil_system.mutex);

		sp = fil_space_get_by_id(id);
	} while (count);

	/* Check for pending IO. */

	for (;;) {
		if (truncate) {
			sp->is_being_truncated = true;
		}

		fil_node_t*	node;

		count = fil_check_pending_io(sp, &node, count);

		if (count == 0 && path) {
			*path = mem_strdup(node->name);
		}

		mutex_exit(&fil_system.mutex);

		if (count == 0) {
			break;
		}

		os_thread_sleep(20000);         // Wait 0.02 seconds
		mutex_enter(&fil_system.mutex);
		sp = fil_space_get_by_id(id);

		if (!sp) {
			mutex_exit(&fil_system.mutex);
			break;
		}
	}

	return sp;
}

/** Close a single-table tablespace on failed IMPORT TABLESPACE.
The tablespace must be cached in the memory cache.
Free all pages used by the tablespace. */
void fil_close_tablespace(ulint id)
{
	ut_ad(!is_system_tablespace(id));
	char* path = nullptr;
	fil_space_t* space = fil_check_pending_operations(id, false, &path);
	if (!space) {
		return;
	}

	rw_lock_x_lock(&space->latch);

	/* Invalidate in the buffer pool all pages belonging to the
	tablespace. Since we have set space->stop_new_ops = true, readahead
	can no longer read more pages of this tablespace to buf_pool.
	Thus we can clean the tablespace out of buf_pool
	completely and permanently. The flag stop_new_ops also prevents
	fil_flush() from being applied to this tablespace. */
	buf_LRU_flush_or_remove_pages(id, true);

	/* If the free is successful, the X lock will be released before
	the space memory data structure is freed. */

	if (!fil_space_free(id, true)) {
		rw_lock_x_unlock(&space->latch);
	}

	/* If it is a delete then also delete any generated files, otherwise
	when we drop the database the remove directory will fail. */

	if (char* cfg_name = fil_make_filepath(path, NULL, CFG, false)) {
		os_file_delete_if_exists(innodb_data_file_key, cfg_name, NULL);
		ut_free(cfg_name);
	}

	ut_free(path);
}

/** Determine whether a table can be accessed in operations that are
not (necessarily) protected by meta-data locks.
(Rollback would generally be protected, but rollback of
FOREIGN KEY CASCADE/SET NULL is not protected by meta-data locks
but only by InnoDB table locks, which may be broken by
lock_remove_all_on_table().)
@param[in]	table	persistent table
checked @return whether the table is accessible */
bool fil_table_accessible(const dict_table_t* table)
{
	if (UNIV_UNLIKELY(!table->is_readable() || table->corrupted)) {
		return(false);
	}

	mutex_enter(&fil_system.mutex);
	bool accessible = table->space && !table->space->is_stopping();
	mutex_exit(&fil_system.mutex);
	ut_ad(accessible || dict_table_is_file_per_table(table));
	return accessible;
}

/** Delete a tablespace and associated .ibd file.
@param[in]	id		tablespace identifier
@param[in]	if_exists	whether to ignore missing tablespace
@return	DB_SUCCESS or error */
dberr_t fil_delete_tablespace(ulint id, bool if_exists)
{
	char* path = NULL;
	ut_ad(!is_system_tablespace(id));

	dberr_t err;
	fil_space_t *space = fil_check_pending_operations(id, false, &path);

	if (!space) {
		err = DB_TABLESPACE_NOT_FOUND;
		if (!if_exists) {
			ib::error() << "Cannot delete tablespace " << id
				    << " because it is not found"
				       " in the tablespace memory cache.";
		}

		goto func_exit;
	}

	/* IMPORTANT: Because we have set space::stop_new_ops there
	can't be any new reads or flushes. We are here
	because node::n_pending was zero above. However, it is still
	possible to have pending read and write requests:

	A read request can happen because the reader thread has
	gone through the ::stop_new_ops check in buf_page_init_for_read()
	before the flag was set and has not yet incremented ::n_pending
	when we checked it above.

	A write request can be issued any time because we don't check
	the ::stop_new_ops flag when queueing a block for write.

	We deal with pending write requests in the following function
	where we'd minimally evict all dirty pages belonging to this
	space from the flush_list. Note that if a block is IO-fixed
	we'll wait for IO to complete.

	To deal with potential read requests, we will check the
	::stop_new_ops flag in fil_io(). */

	err = DB_SUCCESS;
	buf_LRU_flush_or_remove_pages(id, false);

	/* If it is a delete then also delete any generated files, otherwise
	when we drop the database the remove directory will fail. */
	{
		/* Before deleting the file, write a log record about
		it, so that InnoDB crash recovery will expect the file
		to be gone. */
		mtr_t		mtr;

		mtr.start();
		mtr.log_file_op(FILE_DELETE, id, path);
		mtr.commit();
		/* Even if we got killed shortly after deleting the
		tablespace file, the record must have already been
		written to the redo log. */
		log_write_up_to(mtr.commit_lsn(), true);

		char*	cfg_name = fil_make_filepath(path, NULL, CFG, false);
		if (cfg_name != NULL) {
			os_file_delete_if_exists(innodb_data_file_key, cfg_name, NULL);
			ut_free(cfg_name);
		}
	}

	/* Delete the link file pointing to the ibd file we are deleting. */
	if (FSP_FLAGS_HAS_DATA_DIR(space->flags)) {
		RemoteDatafile::delete_link_file(space->name);
	}

	mutex_enter(&fil_system.mutex);

	/* Double check the sanity of pending ops after reacquiring
	the fil_system::mutex. */
	if (const fil_space_t* s = fil_space_get_by_id(id)) {
		ut_a(s == space);
		ut_a(!space->referenced());
		ut_a(UT_LIST_GET_LEN(space->chain) == 1);
		fil_system.detach(space);
		mutex_exit(&fil_system.mutex);

		log_mutex_enter();

		if (space->max_lsn != 0) {
			ut_d(space->max_lsn = 0);
			UT_LIST_REMOVE(fil_system.named_spaces, space);
		}

		log_mutex_exit();
		fil_space_free_low(space);

		if (!os_file_delete(innodb_data_file_key, path)
		    && !os_file_delete_if_exists(
			    innodb_data_file_key, path, NULL)) {

			/* Note: This is because we have removed the
			tablespace instance from the cache. */

			err = DB_IO_ERROR;
		}
	} else {
		mutex_exit(&fil_system.mutex);
		err = DB_TABLESPACE_NOT_FOUND;
	}

func_exit:
	ut_free(path);
	ibuf_delete_for_discarded_space(id);
	return(err);
}

/** Prepare to truncate an undo tablespace.
@param[in]	space_id	undo tablespace id
@return	the tablespace
@retval	NULL if tablespace not found */
fil_space_t *fil_truncate_prepare(ulint space_id)
{
  return fil_check_pending_operations(space_id, true, nullptr);
}

/*******************************************************************//**
Allocates and builds a file name from a path, a table or tablespace name
and a suffix. The string must be freed by caller with ut_free().
@param[in] path NULL or the direcory path or the full path and filename.
@param[in] name NULL if path is full, or Table/Tablespace name
@param[in] suffix NULL or the file extention to use.
@param[in] trim_name true if the last name on the path should be trimmed.
@return own: file name */
char*
fil_make_filepath(
	const char*	path,
	const char*	name,
	ib_extention	ext,
	bool		trim_name)
{
	/* The path may contain the basename of the file, if so we do not
	need the name.  If the path is NULL, we can use the default path,
	but there needs to be a name. */
	ut_ad(path != NULL || name != NULL);

	/* If we are going to strip a name off the path, there better be a
	path and a new name to put back on. */
	ut_ad(!trim_name || (path != NULL && name != NULL));

	if (path == NULL) {
		path = fil_path_to_mysql_datadir;
	}

	ulint	len		= 0;	/* current length */
	ulint	path_len	= strlen(path);
	ulint	name_len	= (name ? strlen(name) : 0);
	const char* suffix	= dot_ext[ext];
	ulint	suffix_len	= strlen(suffix);
	ulint	full_len	= path_len + 1 + name_len + suffix_len + 1;

	char*	full_name = static_cast<char*>(ut_malloc_nokey(full_len));
	if (full_name == NULL) {
		return NULL;
	}

	/* If the name is a relative path, do not prepend "./". */
	if (path[0] == '.'
	    && (path[1] == '\0' || path[1] == OS_PATH_SEPARATOR)
	    && name != NULL && name[0] == '.') {
		path = NULL;
		path_len = 0;
	}

	if (path != NULL) {
		memcpy(full_name, path, path_len);
		len = path_len;
		full_name[len] = '\0';
		os_normalize_path(full_name);
	}

	if (trim_name) {
		/* Find the offset of the last DIR separator and set it to
		null in order to strip off the old basename from this path. */
		char* last_dir_sep = strrchr(full_name, OS_PATH_SEPARATOR);
		if (last_dir_sep) {
			last_dir_sep[0] = '\0';
			len = strlen(full_name);
		}
	}

	if (name != NULL) {
		if (len && full_name[len - 1] != OS_PATH_SEPARATOR) {
			/* Add a DIR separator */
			full_name[len] = OS_PATH_SEPARATOR;
			full_name[++len] = '\0';
		}

		char*	ptr = &full_name[len];
		memcpy(ptr, name, name_len);
		len += name_len;
		full_name[len] = '\0';
		os_normalize_path(ptr);
	}

	/* Make sure that the specified suffix is at the end of the filepath
	string provided. This assumes that the suffix starts with '.'.
	If the first char of the suffix is found in the filepath at the same
	length as the suffix from the end, then we will assume that there is
	a previous suffix that needs to be replaced. */
	if (suffix != NULL) {
		/* Need room for the trailing null byte. */
		ut_ad(len < full_len);

		if ((len > suffix_len)
		   && (full_name[len - suffix_len] == suffix[0])) {
			/* Another suffix exists, make it the one requested. */
			memcpy(&full_name[len - suffix_len], suffix, suffix_len);

		} else {
			/* No previous suffix, add it. */
			ut_ad(len + suffix_len < full_len);
			memcpy(&full_name[len], suffix, suffix_len);
			full_name[len + suffix_len] = '\0';
		}
	}

	return(full_name);
}

/** Test if a tablespace file can be renamed to a new filepath by checking
if that the old filepath exists and the new filepath does not exist.
@param[in]	old_path	old filepath
@param[in]	new_path	new filepath
@param[in]	is_discarded	whether the tablespace is discarded
@param[in]	replace_new	whether to ignore the existence of new_path
@return innodb error code */
static dberr_t
fil_rename_tablespace_check(
	const char*	old_path,
	const char*	new_path,
	bool		is_discarded,
	bool		replace_new)
{
	bool	exists = false;
	os_file_type_t	ftype;

	if (!is_discarded
	    && os_file_status(old_path, &exists, &ftype)
	    && !exists) {
		ib::error() << "Cannot rename '" << old_path
			<< "' to '" << new_path
			<< "' because the source file"
			<< " does not exist.";
		return(DB_TABLESPACE_NOT_FOUND);
	}

	exists = false;
	if (os_file_status(new_path, &exists, &ftype) && !exists) {
		return DB_SUCCESS;
	}

	if (!replace_new) {
		ib::error() << "Cannot rename '" << old_path
			<< "' to '" << new_path
			<< "' because the target file exists."
			" Remove the target file and try again.";
		return(DB_TABLESPACE_EXISTS);
	}

	/* This must be during the ROLLBACK of TRUNCATE TABLE.
	Because InnoDB only allows at most one data dictionary
	transaction at a time, and because this incomplete TRUNCATE
	would have created a new tablespace file, we must remove
	a possibly existing tablespace that is associated with the
	new tablespace file. */
retry:
	mutex_enter(&fil_system.mutex);
	for (fil_space_t* space = UT_LIST_GET_FIRST(fil_system.space_list);
	     space; space = UT_LIST_GET_NEXT(space_list, space)) {
		ulint id = space->id;
		if (id
		    && space->purpose == FIL_TYPE_TABLESPACE
		    && !strcmp(new_path,
			       UT_LIST_GET_FIRST(space->chain)->name)) {
			ib::info() << "TRUNCATE rollback: " << id
				<< "," << new_path;
			mutex_exit(&fil_system.mutex);
			dberr_t err = fil_delete_tablespace(id);
			if (err != DB_SUCCESS) {
				return err;
			}
			goto retry;
		}
	}
	mutex_exit(&fil_system.mutex);
	fil_delete_file(new_path);

	return(DB_SUCCESS);
}

dberr_t fil_space_t::rename(const char* name, const char* path, bool log,
			    bool replace)
{
	ut_ad(UT_LIST_GET_LEN(chain) == 1);
	ut_ad(!is_system_tablespace(id));

	if (log) {
		dberr_t err = fil_rename_tablespace_check(
			chain.start->name, path, false, replace);
		if (err != DB_SUCCESS) {
			return(err);
		}
		fil_name_write_rename(id, chain.start->name, path);
	}

	return fil_rename_tablespace(id, chain.start->name, name, path)
		? DB_SUCCESS : DB_ERROR;
}

/** Rename a single-table tablespace.
The tablespace must exist in the memory cache.
@param[in]	id		tablespace identifier
@param[in]	old_path	old file name
@param[in]	new_name	new table name in the
databasename/tablename format
@param[in]	new_path_in	new file name,
or NULL if it is located in the normal data directory
@return true if success */
static bool
fil_rename_tablespace(
	ulint		id,
	const char*	old_path,
	const char*	new_name,
	const char*	new_path_in)
{
	fil_space_t*	space;
	fil_node_t*	node;
	ut_a(id != 0);

	ut_ad(strchr(new_name, '/') != NULL);

	mutex_enter(&fil_system.mutex);

	space = fil_space_get_by_id(id);

	if (space == NULL) {
		ib::error() << "Cannot find space id " << id
			<< " in the tablespace memory cache, though the file '"
			<< old_path
			<< "' in a rename operation should have that id.";
		mutex_exit(&fil_system.mutex);
		return(false);
	}

	/* The following code must change when InnoDB supports
	multiple datafiles per tablespace. */
	ut_a(UT_LIST_GET_LEN(space->chain) == 1);
	node = UT_LIST_GET_FIRST(space->chain);
	space->n_pending_ops++;

	mutex_exit(&fil_system.mutex);

	char*	new_file_name = new_path_in == NULL
		? fil_make_filepath(NULL, new_name, IBD, false)
		: mem_strdup(new_path_in);
	char*	old_file_name = node->name;
	char*	new_space_name = mem_strdup(new_name);
	char*	old_space_name = space->name;

	ut_ad(strchr(old_file_name, OS_PATH_SEPARATOR) != NULL);
	ut_ad(strchr(new_file_name, OS_PATH_SEPARATOR) != NULL);

	if (!recv_recovery_is_on()) {
		fil_name_write_rename(id, old_file_name, new_file_name);
		log_mutex_enter();
	}

	/* log_sys.mutex is above fil_system.mutex in the latching order */
	ut_ad(log_mutex_own());
	mutex_enter(&fil_system.mutex);
	ut_ad(space->n_pending_ops);
	space->n_pending_ops--;
	ut_ad(space->name == old_space_name);
	ut_ad(node->name == old_file_name);
	bool success;
	DBUG_EXECUTE_IF("fil_rename_tablespace_failure_2",
			goto skip_second_rename; );
	success = os_file_rename(innodb_data_file_key,
				 old_file_name,
				 new_file_name);
	DBUG_EXECUTE_IF("fil_rename_tablespace_failure_2",
skip_second_rename:
                       success = false; );

	ut_ad(node->name == old_file_name);

	if (success) {
		node->name = new_file_name;
	}

	if (!recv_recovery_is_on()) {
		log_mutex_exit();
	}

	ut_ad(space->name == old_space_name);
	if (success) {
		space->name = new_space_name;
	} else {
		/* Because nothing was renamed, we must free the new
		names, not the old ones. */
		old_file_name = new_file_name;
		old_space_name = new_space_name;
	}

	mutex_exit(&fil_system.mutex);

	ut_free(old_file_name);
	ut_free(old_space_name);

	return(success);
}

/* FIXME: remove this! */
IF_WIN(, bool os_is_sparse_file_supported(os_file_t fh));

/** Create a tablespace file.
@param[in]	space_id	Tablespace ID
@param[in]	name		Tablespace name in dbname/tablename format.
@param[in]	path		Path and filename of the datafile to create.
@param[in]	flags		Tablespace flags
@param[in]	size		Initial size of the tablespace file in pages,
must be >= FIL_IBD_FILE_INITIAL_SIZE
@param[in]	mode		MariaDB encryption mode
@param[in]	key_id		MariaDB encryption key_id
@param[out]	err		DB_SUCCESS or error code
@return	the created tablespace
@retval	NULL	on error */
fil_space_t*
fil_ibd_create(
	ulint		space_id,
	const char*	name,
	const char*	path,
	ulint		flags,
	ulint		size,
	fil_encryption_t mode,
	uint32_t	key_id,
	dberr_t*	err)
{
	pfs_os_file_t	file;
	byte*		page;
	bool		success;
	bool		has_data_dir = FSP_FLAGS_HAS_DATA_DIR(flags) != 0;

	ut_ad(!is_system_tablespace(space_id));
	ut_ad(!srv_read_only_mode);
	ut_a(space_id < SRV_SPACE_ID_UPPER_BOUND);
	ut_a(size >= FIL_IBD_FILE_INITIAL_SIZE);
	ut_a(fil_space_t::is_valid_flags(flags & ~FSP_FLAGS_MEM_MASK, space_id));

	/* Create the subdirectories in the path, if they are
	not there already. */
	*err = os_file_create_subdirs_if_needed(path);
	if (*err != DB_SUCCESS) {
		return NULL;
	}

	file = os_file_create(
		innodb_data_file_key, path,
		OS_FILE_CREATE | OS_FILE_ON_ERROR_NO_EXIT,
		OS_FILE_NORMAL,
		OS_DATA_FILE,
		srv_read_only_mode,
		&success);

	if (!success) {
		/* The following call will print an error message */
		switch (os_file_get_last_error(true)) {
		case OS_FILE_ALREADY_EXISTS:
			ib::info() << "The file '" << path << "'"
				" already exists though the"
				" corresponding table did not exist"
				" in the InnoDB data dictionary."
				" You can resolve the problem by removing"
				" the file.";
			*err = DB_TABLESPACE_EXISTS;
			break;
		case OS_FILE_DISK_FULL:
			*err = DB_OUT_OF_FILE_SPACE;
			break;
		default:
			*err = DB_ERROR;
		}
		ib::error() << "Cannot create file '" << path << "'";
		return NULL;
	}

	const bool is_compressed = FSP_FLAGS_HAS_PAGE_COMPRESSION(flags);
	bool punch_hole = is_compressed;

#ifdef _WIN32
	if (is_compressed) {
		os_file_set_sparse_win32(file);
	}
#endif

	if (!os_file_set_size(
		path, file,
		os_offset_t(size) << srv_page_size_shift, is_compressed)) {
		*err = DB_OUT_OF_FILE_SPACE;
err_exit:
		os_file_close(file);
		os_file_delete(innodb_data_file_key, path);
		return NULL;
	}

	/* FIXME: remove this */
	IF_WIN(, punch_hole = punch_hole && os_is_sparse_file_supported(file));

	/* We have to write the space id to the file immediately and flush the
	file to disk. This is because in crash recovery we must be aware what
	tablespaces exist and what are their space id's, so that we can apply
	the log records to the right file. It may take quite a while until
	buffer pool flush algorithms write anything to the file and flush it to
	disk. If we would not write here anything, the file would be filled
	with zeros from the call of os_file_set_size(), until a buffer pool
	flush would write to it. */

	/* Align the memory for file i/o if we might have O_DIRECT set */
	page = static_cast<byte*>(aligned_malloc(2 * srv_page_size,
						 srv_page_size));

	memset(page, '\0', srv_page_size);

	if (fil_space_t::full_crc32(flags)) {
		flags |= FSP_FLAGS_FCRC32_PAGE_SSIZE();
	} else {
		flags |= FSP_FLAGS_PAGE_SSIZE();
	}

	fsp_header_init_fields(page, space_id, flags);
	mach_write_to_4(page + FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID, space_id);

	/* Create crypt data if the tablespace is either encrypted or user has
	requested it to remain unencrypted. */
	fil_space_crypt_t *crypt_data = (mode != FIL_ENCRYPTION_DEFAULT
					 || srv_encrypt_tables)
		? fil_space_create_crypt_data(mode, key_id)
		: NULL;

	if (crypt_data) {
		/* Write crypt data information in page0 while creating
		ibd file. */
		crypt_data->fill_page0(flags, page);
	}

	if (ulint zip_size = fil_space_t::zip_size(flags)) {
		page_zip_des_t	page_zip;
		page_zip_set_size(&page_zip, zip_size);
		page_zip.data = page + srv_page_size;
#ifdef UNIV_DEBUG
		page_zip.m_start = 0;
#endif /* UNIV_DEBUG */
		page_zip.m_end = 0;
		page_zip.m_nonempty = 0;
		page_zip.n_blobs = 0;

		buf_flush_init_for_writing(NULL, page, &page_zip, false);

		*err = os_file_write(
			IORequestWrite, path, file, page_zip.data, 0, zip_size);
	} else {
		buf_flush_init_for_writing(NULL, page, NULL,
					   fil_space_t::full_crc32(flags));

		*err = os_file_write(
			IORequestWrite, path, file, page, 0, srv_page_size);
	}

	aligned_free(page);

	if (*err != DB_SUCCESS) {
		ib::error()
			<< "Could not write the first page to"
			<< " tablespace '" << path << "'";
		goto err_exit;
	}

	if (!os_file_flush(file)) {
		ib::error() << "File flush of tablespace '"
			<< path << "' failed";
		*err = DB_ERROR;
		goto err_exit;
	}

	if (has_data_dir) {
		/* Make the ISL file if the IBD file is not
		in the default location. */
		*err = RemoteDatafile::create_link_file(name, path);
		if (*err != DB_SUCCESS) {
			goto err_exit;
		}
	}

	fil_space_t* space = fil_space_create(name, space_id, flags,
					      FIL_TYPE_TABLESPACE,
					      crypt_data, mode);
	if (!space) {
		free(crypt_data);
		*err = DB_ERROR;
	} else {
		space->punch_hole = punch_hole;
		/* FIXME: Keep the file open! */
		fil_node_t* node = space->add(path, OS_FILE_CLOSED, size,
					      false, true);
		mtr_t mtr;
		mtr.start();
		mtr.log_file_op(FILE_CREATE, space_id, node->name);
		mtr.commit();

		node->find_metadata(file);
		*err = DB_SUCCESS;
	}

	os_file_close(file);

	if (*err != DB_SUCCESS) {
		if (has_data_dir) {
			RemoteDatafile::delete_link_file(name);
		}

		os_file_delete(innodb_data_file_key, path);
	}

	return space;
}

/** Try to open a single-table tablespace and optionally check that the
space id in it is correct. If this does not succeed, print an error message
to the .err log. This function is used to open a tablespace when we start
mysqld after the dictionary has been booted, and also in IMPORT TABLESPACE.

NOTE that we assume this operation is used either at the database startup
or under the protection of the dictionary mutex, so that two users cannot
race here. This operation does not leave the file associated with the
tablespace open, but closes it after we have looked at the space id in it.

If the validate boolean is set, we read the first page of the file and
check that the space id in the file is what we expect. We assume that
this function runs much faster if no check is made, since accessing the
file inode probably is much faster (the OS caches them) than accessing
the first page of the file.  This boolean may be initially false, but if
a remote tablespace is found it will be changed to true.

If the fix_dict boolean is set, then it is safe to use an internal SQL
statement to update the dictionary tables if they are incorrect.

@param[in]	validate	true if we should validate the tablespace
@param[in]	fix_dict	true if the dictionary is available to be fixed
@param[in]	purpose		FIL_TYPE_TABLESPACE or FIL_TYPE_TEMPORARY
@param[in]	id		tablespace ID
@param[in]	flags		expected FSP_SPACE_FLAGS
@param[in]	space_name	tablespace name of the datafile
If file-per-table, it is the table name in the databasename/tablename format
@param[in]	path_in		expected filepath, usually read from dictionary
@param[out]	err		DB_SUCCESS or error code
@return	tablespace
@retval	NULL	if the tablespace could not be opened */
fil_space_t*
fil_ibd_open(
	bool			validate,
	bool			fix_dict,
	fil_type_t		purpose,
	ulint			id,
	ulint			flags,
	const table_name_t&	tablename,
	const char*		path_in,
	dberr_t*		err)
{
	mutex_enter(&fil_system.mutex);
	if (fil_space_t* space = fil_space_get_by_id(id)) {
		if (strcmp(space->name, tablename.m_name)) {
			table_name_t space_name;
			space_name.m_name = space->name;
			ib::error()
				<< "Trying to open table " << tablename
				<< " with id " << id
				<< ", conflicting with " << space_name;
			space = NULL;
			if (err) *err = DB_TABLESPACE_EXISTS;
		} else if (err) *err = DB_SUCCESS;

		mutex_exit(&fil_system.mutex);

		if (space && validate && !srv_read_only_mode) {
			fsp_flags_try_adjust(space,
					     flags & ~FSP_FLAGS_MEM_MASK);
		}

		return space;
	}
	mutex_exit(&fil_system.mutex);

	bool		dict_filepath_same_as_default = false;
	bool		link_file_found = false;
	bool		link_file_is_bad = false;
	Datafile	df_default;	/* default location */
	Datafile	df_dict;	/* dictionary location */
	RemoteDatafile	df_remote;	/* remote location */
	ulint		tablespaces_found = 0;
	ulint		valid_tablespaces_found = 0;

	if (fix_dict) {
		ut_d(dict_sys.assert_locked());
		ut_ad(!srv_read_only_mode);
		ut_ad(srv_log_file_size != 0);
	}

	/* Table flags can be ULINT_UNDEFINED if
	dict_tf_to_fsp_flags_failure is set. */
	if (flags == ULINT_UNDEFINED) {
corrupted:
		if (err) *err = DB_CORRUPTION;
		return NULL;
	}

	ut_ad(fil_space_t::is_valid_flags(flags & ~FSP_FLAGS_MEM_MASK, id));
	df_default.init(tablename.m_name, flags);
	df_dict.init(tablename.m_name, flags);
	df_remote.init(tablename.m_name, flags);

	/* Discover the correct file by looking in three possible locations
	while avoiding unecessary effort. */

	/* We will always look for an ibd in the default location. */
	df_default.make_filepath(NULL, tablename.m_name, IBD);

	/* Look for a filepath embedded in an ISL where the default file
	would be. */
	if (df_remote.open_read_only(true) == DB_SUCCESS) {
		ut_ad(df_remote.is_open());

		/* Always validate a file opened from an ISL pointer */
		validate = true;
		++tablespaces_found;
		link_file_found = true;
	} else if (df_remote.filepath() != NULL) {
		/* An ISL file was found but contained a bad filepath in it.
		Better validate anything we do find. */
		validate = true;
	}

	/* Attempt to open the tablespace at the dictionary filepath. */
	if (path_in) {
		if (df_default.same_filepath_as(path_in)) {
			dict_filepath_same_as_default = true;
		} else {
			/* Dict path is not the default path. Always validate
			remote files. If default is opened, it was moved. */
			validate = true;
			df_dict.set_filepath(path_in);
			if (df_dict.open_read_only(true) == DB_SUCCESS) {
				ut_ad(df_dict.is_open());
				++tablespaces_found;
			}
		}
	}

	/* Always look for a file at the default location. But don't log
	an error if the tablespace is already open in remote or dict. */
	ut_a(df_default.filepath());
	const bool	strict = (tablespaces_found == 0);
	if (df_default.open_read_only(strict) == DB_SUCCESS) {
		ut_ad(df_default.is_open());
		++tablespaces_found;
	}

	/* Check if multiple locations point to the same file. */
	if (tablespaces_found > 1 && df_default.same_as(df_remote)) {
		/* A link file was found with the default path in it.
		Use the default path and delete the link file. */
		--tablespaces_found;
		df_remote.delete_link_file();
		df_remote.close();
	}
	if (tablespaces_found > 1 && df_default.same_as(df_dict)) {
		--tablespaces_found;
		df_dict.close();
	}
	if (tablespaces_found > 1 && df_remote.same_as(df_dict)) {
		--tablespaces_found;
		df_dict.close();
	}

	/*  We have now checked all possible tablespace locations and
	have a count of how many unique files we found.  If things are
	normal, we only found 1. */
	/* For encrypted tablespace, we need to check the
	encryption in header of first page. */
	if (!validate && tablespaces_found == 1) {
		goto skip_validate;
	}

	/* Read and validate the first page of these three tablespace
	locations, if found. */
	valid_tablespaces_found +=
		(df_remote.validate_to_dd(id, flags) == DB_SUCCESS);

	valid_tablespaces_found +=
		(df_default.validate_to_dd(id, flags) == DB_SUCCESS);

	valid_tablespaces_found +=
		(df_dict.validate_to_dd(id, flags) == DB_SUCCESS);

	/* Make sense of these three possible locations.
	First, bail out if no tablespace files were found. */
	if (valid_tablespaces_found == 0) {
		os_file_get_last_error(true);
		ib::error() << "Could not find a valid tablespace file for `"
			<< tablename << "`. " << TROUBLESHOOT_DATADICT_MSG;
		goto corrupted;
	}
	if (!validate) {
		goto skip_validate;
	}

	/* Do not open any tablespaces if more than one tablespace with
	the correct space ID and flags were found. */
	if (tablespaces_found > 1) {
		ib::error() << "A tablespace for `" << tablename
			<< "` has been found in multiple places;";

		if (df_default.is_open()) {
			ib::error() << "Default location: "
				<< df_default.filepath()
				<< ", Space ID=" << df_default.space_id()
				<< ", Flags=" << df_default.flags();
		}
		if (df_remote.is_open()) {
			ib::error() << "Remote location: "
				<< df_remote.filepath()
				<< ", Space ID=" << df_remote.space_id()
				<< ", Flags=" << df_remote.flags();
		}
		if (df_dict.is_open()) {
			ib::error() << "Dictionary location: "
				<< df_dict.filepath()
				<< ", Space ID=" << df_dict.space_id()
				<< ", Flags=" << df_dict.flags();
		}

		/* Force-recovery will allow some tablespaces to be
		skipped by REDO if there was more than one file found.
		Unlike during the REDO phase of recovery, we now know
		if the tablespace is valid according to the dictionary,
		which was not available then. So if we did not force
		recovery and there is only one good tablespace, ignore
		any bad tablespaces. */
		if (valid_tablespaces_found > 1 || srv_force_recovery > 0) {
			ib::error() << "Will not open tablespace `"
				<< tablename << "`";

			/* If the file is not open it cannot be valid. */
			ut_ad(df_default.is_open() || !df_default.is_valid());
			ut_ad(df_dict.is_open()    || !df_dict.is_valid());
			ut_ad(df_remote.is_open()  || !df_remote.is_valid());

			/* Having established that, this is an easy way to
			look for corrupted data files. */
			if (df_default.is_open() != df_default.is_valid()
			    || df_dict.is_open() != df_dict.is_valid()
			    || df_remote.is_open() != df_remote.is_valid()) {
				goto corrupted;
			}
error:
			if (err) *err = DB_ERROR;
			return NULL;
		}

		/* There is only one valid tablespace found and we did
		not use srv_force_recovery during REDO.  Use this one
		tablespace and clean up invalid tablespace pointers */
		if (df_default.is_open() && !df_default.is_valid()) {
			df_default.close();
			tablespaces_found--;
		}

		if (df_dict.is_open() && !df_dict.is_valid()) {
			df_dict.close();
			/* Leave dict.filepath so that SYS_DATAFILES
			can be corrected below. */
			tablespaces_found--;
		}

		if (df_remote.is_open() && !df_remote.is_valid()) {
			df_remote.close();
			tablespaces_found--;
			link_file_is_bad = true;
		}
	}

	/* At this point, there should be only one filepath. */
	ut_a(tablespaces_found == 1);
	ut_a(valid_tablespaces_found == 1);

	/* Only fix the dictionary at startup when there is only one thread.
	Calls to dict_load_table() can be done while holding other latches. */
	if (!fix_dict) {
		goto skip_validate;
	}

	/* We may need to update what is stored in SYS_DATAFILES or
	SYS_TABLESPACES or adjust the link file.  Since a failure to
	update SYS_TABLESPACES or SYS_DATAFILES does not prevent opening
	and using the tablespace either this time or the next, we do not
	check the return code or fail to open the tablespace. But if it
	fails, dict_update_filepath() will issue a warning to the log. */
	if (df_dict.filepath()) {
		ut_ad(path_in != NULL);
		ut_ad(df_dict.same_filepath_as(path_in));

		if (df_remote.is_open()) {
			if (!df_remote.same_filepath_as(path_in)) {
				dict_update_filepath(id, df_remote.filepath());
			}

		} else if (df_default.is_open()) {
			ut_ad(!dict_filepath_same_as_default);
			dict_update_filepath(id, df_default.filepath());
			if (link_file_is_bad) {
				RemoteDatafile::delete_link_file(
					tablename.m_name);
			}

		} else if (!link_file_found || link_file_is_bad) {
			ut_ad(df_dict.is_open());
			/* Fix the link file if we got our filepath
			from the dictionary but a link file did not
			exist or it did not point to a valid file. */
			RemoteDatafile::delete_link_file(tablename.m_name);
			RemoteDatafile::create_link_file(
				tablename.m_name, df_dict.filepath());
		}

	} else if (df_remote.is_open()) {
		if (dict_filepath_same_as_default) {
			dict_update_filepath(id, df_remote.filepath());

		} else if (path_in == NULL) {
			/* SYS_DATAFILES record for this space ID
			was not found. */
			dict_replace_tablespace_and_filepath(
				id, tablename.m_name,
				df_remote.filepath(), flags);
		}

	} else if (df_default.is_open()) {
		/* We opened the tablespace in the default location.
		SYS_DATAFILES.PATH needs to be updated if it is different
		from this default path or if the SYS_DATAFILES.PATH was not
		supplied and it should have been. Also update the dictionary
		if we found an ISL file (since !df_remote.is_open).  Since
		path_in is not suppled for file-per-table, we must assume
		that it matched the ISL. */
		if ((path_in != NULL && !dict_filepath_same_as_default)
		    || (path_in == NULL && DICT_TF_HAS_DATA_DIR(flags))
		    || df_remote.filepath() != NULL) {
			dict_replace_tablespace_and_filepath(
				id, tablename.m_name, df_default.filepath(),
				flags);
		}
	}

skip_validate:
	const byte* first_page =
		df_default.is_open() ? df_default.get_first_page() :
		df_dict.is_open() ? df_dict.get_first_page() :
		df_remote.get_first_page();

	fil_space_crypt_t* crypt_data = first_page
		? fil_space_read_crypt_data(fil_space_t::zip_size(flags),
					    first_page)
		: NULL;

	fil_space_t* space = fil_space_create(
		tablename.m_name, id, flags, purpose, crypt_data);
	if (!space) {
		goto error;
	}

	/* We do not measure the size of the file, that is why
	we pass the 0 below */

	space->add(
		df_remote.is_open() ? df_remote.filepath() :
		df_dict.is_open() ? df_dict.filepath() :
		df_default.filepath(), OS_FILE_CLOSED, 0, false, true);

	if (validate && purpose != FIL_TYPE_IMPORT && !srv_read_only_mode) {
		df_remote.close();
		df_dict.close();
		df_default.close();
		fsp_flags_try_adjust(space, flags & ~FSP_FLAGS_MEM_MASK);
	}

	if (err) *err = DB_SUCCESS;
	return space;
}

/** Looks for a pre-existing fil_space_t with the given tablespace ID
and, if found, returns the name and filepath in newly allocated buffers
that the caller must free.
@param[in]	space_id	The tablespace ID to search for.
@param[out]	name		Name of the tablespace found.
@param[out]	filepath	The filepath of the first datafile for the
tablespace.
@return true if tablespace is found, false if not. */
bool
fil_space_read_name_and_filepath(
	ulint	space_id,
	char**	name,
	char**	filepath)
{
	bool	success = false;
	*name = NULL;
	*filepath = NULL;

	mutex_enter(&fil_system.mutex);

	fil_space_t*	space = fil_space_get_by_id(space_id);

	if (space != NULL) {
		*name = mem_strdup(space->name);

		fil_node_t* node = UT_LIST_GET_FIRST(space->chain);
		*filepath = mem_strdup(node->name);

		success = true;
	}

	mutex_exit(&fil_system.mutex);

	return(success);
}

/** Convert a file name to a tablespace name.
@param[in]	filename	directory/databasename/tablename.ibd
@return database/tablename string, to be freed with ut_free() */
char*
fil_path_to_space_name(
	const char*	filename)
{
	/* Strip the file name prefix and suffix, leaving
	only databasename/tablename. */
	ulint		filename_len	= strlen(filename);
	const char*	end		= filename + filename_len;
#ifdef HAVE_MEMRCHR
	const char*	tablename	= 1 + static_cast<const char*>(
		memrchr(filename, OS_PATH_SEPARATOR,
			filename_len));
	const char*	dbname		= 1 + static_cast<const char*>(
		memrchr(filename, OS_PATH_SEPARATOR,
			tablename - filename - 1));
#else /* HAVE_MEMRCHR */
	const char*	tablename	= filename;
	const char*	dbname		= NULL;

	while (const char* t = static_cast<const char*>(
		       memchr(tablename, OS_PATH_SEPARATOR,
			      ulint(end - tablename)))) {
		dbname = tablename;
		tablename = t + 1;
	}
#endif /* HAVE_MEMRCHR */

	ut_ad(dbname != NULL);
	ut_ad(tablename > dbname);
	ut_ad(tablename < end);
	ut_ad(end - tablename > 4);
	ut_ad(memcmp(end - 4, DOT_IBD, 4) == 0);

	char*	name = mem_strdupl(dbname, ulint(end - dbname) - 4);

	ut_ad(name[tablename - dbname - 1] == OS_PATH_SEPARATOR);
#if OS_PATH_SEPARATOR != '/'
	/* space->name uses '/', not OS_PATH_SEPARATOR. */
	name[tablename - dbname - 1] = '/';
#endif

	return(name);
}

/** Discover the correct IBD file to open given a remote or missing
filepath from the REDO log. Administrators can move a crashed
database to another location on the same machine and try to recover it.
Remote IBD files might be moved as well to the new location.
    The problem with this is that the REDO log contains the old location
which may be still accessible.  During recovery, if files are found in
both locations, we can chose on based on these priorities;
1. Default location
2. ISL location
3. REDO location
@param[in]	space_id	tablespace ID
@param[in]	df		Datafile object with path from redo
@return true if a valid datafile was found, false if not */
static
bool
fil_ibd_discover(
	ulint		space_id,
	Datafile&	df)
{
	Datafile	df_def_per;	/* default file-per-table datafile */
	RemoteDatafile	df_rem_per;	/* remote file-per-table datafile */

	/* Look for the datafile in the default location. */
	const char*	filename = df.filepath();
	const char*	basename = base_name(filename);

	/* If this datafile is file-per-table it will have a schema dir. */
	ulint		sep_found = 0;
	const char*	db = basename;
	for (; db > filename && sep_found < 2; db--) {
		if (db[0] == OS_PATH_SEPARATOR) {
			sep_found++;
		}
	}
	if (sep_found == 2) {
		db += 2;
		df_def_per.init(db, 0);
		df_def_per.make_filepath(NULL, db, IBD);
		if (df_def_per.open_read_only(false) == DB_SUCCESS
		    && df_def_per.validate_for_recovery() == DB_SUCCESS
		    && df_def_per.space_id() == space_id) {
			df.set_filepath(df_def_per.filepath());
			df.open_read_only(false);
			return(true);
		}

		/* Look for a remote file-per-table tablespace. */

		switch (srv_operation) {
		case SRV_OPERATION_BACKUP:
		case SRV_OPERATION_RESTORE_DELTA:
			ut_ad(0);
			break;
		case SRV_OPERATION_RESTORE_EXPORT:
		case SRV_OPERATION_RESTORE:
			break;
		case SRV_OPERATION_NORMAL:
			df_rem_per.set_name(db);
			if (df_rem_per.open_link_file() != DB_SUCCESS) {
				break;
			}

			/* An ISL file was found with contents. */
			if (df_rem_per.open_read_only(false) != DB_SUCCESS
				|| df_rem_per.validate_for_recovery()
				   != DB_SUCCESS) {

				/* Assume that this ISL file is intended to
				be used. Do not continue looking for another
				if this file cannot be opened or is not
				a valid IBD file. */
				ib::error() << "ISL file '"
					<< df_rem_per.link_filepath()
					<< "' was found but the linked file '"
					<< df_rem_per.filepath()
					<< "' could not be opened or is"
					" not correct.";
				return(false);
			}

			/* Use this file if it has the space_id from the
			MLOG record. */
			if (df_rem_per.space_id() == space_id) {
				df.set_filepath(df_rem_per.filepath());
				df.open_read_only(false);
				return(true);
			}

			/* Since old MLOG records can use the same basename
			in multiple CREATE/DROP TABLE sequences, this ISL
			file could be pointing to a later version of this
			basename.ibd file which has a different space_id.
			Keep looking. */
		}
	}

	/* No ISL files were found in the default location. Use the location
	given in the redo log. */
	if (df.open_read_only(false) == DB_SUCCESS
	    && df.validate_for_recovery() == DB_SUCCESS
	    && df.space_id() == space_id) {
		return(true);
	}

	/* A datafile was not discovered for the filename given. */
	return(false);
}
/** Open an ibd tablespace and add it to the InnoDB data structures.
This is similar to fil_ibd_open() except that it is used while processing
the REDO log, so the data dictionary is not available and very little
validation is done. The tablespace name is extracred from the
dbname/tablename.ibd portion of the filename, which assumes that the file
is a file-per-table tablespace.  Any name will do for now.  General
tablespace names will be read from the dictionary after it has been
recovered.  The tablespace flags are read at this time from the first page
of the file in validate_for_recovery().
@param[in]	space_id	tablespace ID
@param[in]	filename	path/to/databasename/tablename.ibd
@param[out]	space		the tablespace, or NULL on error
@return status of the operation */
enum fil_load_status
fil_ibd_load(
	ulint		space_id,
	const char*	filename,
	fil_space_t*&	space)
{
	/* If the a space is already in the file system cache with this
	space ID, then there is nothing to do. */
	mutex_enter(&fil_system.mutex);
	space = fil_space_get_by_id(space_id);
	mutex_exit(&fil_system.mutex);

	if (space != NULL) {
		/* Compare the filename we are trying to open with the
		filename from the first node of the tablespace we opened
		previously. Fail if it is different. */
		fil_node_t* node = UT_LIST_GET_FIRST(space->chain);
		if (0 != strcmp(innobase_basename(filename),
				innobase_basename(node->name))) {
			ib::info()
				<< "Ignoring data file '" << filename
				<< "' with space ID " << space->id
				<< ". Another data file called " << node->name
				<< " exists with the same space ID.";
				space = NULL;
				return(FIL_LOAD_ID_CHANGED);
		}
		return(FIL_LOAD_OK);
	}

	if (srv_operation == SRV_OPERATION_RESTORE) {
		/* Replace absolute DATA DIRECTORY file paths with
		short names relative to the backup directory. */
		if (const char* name = strrchr(filename, OS_PATH_SEPARATOR)) {
			while (--name > filename
			       && *name != OS_PATH_SEPARATOR);
			if (name > filename) {
				filename = name + 1;
			}
		}
	}

	Datafile	file;
	file.set_filepath(filename);
	file.open_read_only(false);

	if (!file.is_open()) {
		/* The file has been moved or it is a remote datafile. */
		if (!fil_ibd_discover(space_id, file)
		    || !file.is_open()) {
			return(FIL_LOAD_NOT_FOUND);
		}
	}

	os_offset_t	size;

	/* Read and validate the first page of the tablespace.
	Assign a tablespace name based on the tablespace type. */
	switch (file.validate_for_recovery()) {
		os_offset_t	minimum_size;
	case DB_SUCCESS:
		if (file.space_id() != space_id) {
			ib::info()
				<< "Ignoring data file '"
				<< file.filepath()
				<< "' with space ID " << file.space_id()
				<< ", since the redo log references "
				<< file.filepath() << " with space ID "
				<< space_id << ".";
			return(FIL_LOAD_ID_CHANGED);
		}
		/* Get and test the file size. */
		size = os_file_get_size(file.handle());

		/* Every .ibd file is created >= 4 pages in size.
		Smaller files cannot be OK. */
		minimum_size = os_offset_t(FIL_IBD_FILE_INITIAL_SIZE)
			<< srv_page_size_shift;

		if (size == static_cast<os_offset_t>(-1)) {
			/* The following call prints an error message */
			os_file_get_last_error(true);

			ib::error() << "Could not measure the size of"
				" single-table tablespace file '"
				<< file.filepath() << "'";
		} else if (size < minimum_size) {
			ib::error() << "The size of tablespace file '"
				<< file.filepath() << "' is only " << size
				<< ", should be at least " << minimum_size
				<< "!";
		} else {
			/* Everything is fine so far. */
			break;
		}

		/* fall through */

	case DB_TABLESPACE_EXISTS:
		return(FIL_LOAD_INVALID);

	default:
		return(FIL_LOAD_NOT_FOUND);
	}

	ut_ad(space == NULL);

	/* Adjust the memory-based flags that would normally be set by
	dict_tf_to_fsp_flags(). In recovery, we have no data dictionary. */
	ulint flags = file.flags();
	if (FSP_FLAGS_HAS_PAGE_COMPRESSION(flags)) {
		flags |= page_zip_level
			<< FSP_FLAGS_MEM_COMPRESSION_LEVEL;
	}

	const byte* first_page = file.get_first_page();
	fil_space_crypt_t* crypt_data = first_page
		? fil_space_read_crypt_data(fil_space_t::zip_size(flags),
					    first_page)
		: NULL;
	space = fil_space_create(
		file.name(), space_id, flags, FIL_TYPE_TABLESPACE, crypt_data);

	if (space == NULL) {
		return(FIL_LOAD_INVALID);
	}

	ut_ad(space->id == file.space_id());
	ut_ad(space->id == space_id);

	/* We do not use the size information we have about the file, because
	the rounding formula for extents and pages is somewhat complex; we
	let fil_node_open() do that task. */

	space->add(file.filepath(), OS_FILE_CLOSED, 0, false, false);

	return(FIL_LOAD_OK);
}

/***********************************************************************//**
A fault-tolerant function that tries to read the next file name in the
directory. We retry 100 times if os_file_readdir_next_file() returns -1. The
idea is to read as much good data as we can and jump over bad data.
@return 0 if ok, -1 if error even after the retries, 1 if at the end
of the directory */
int
fil_file_readdir_next_file(
/*=======================*/
	dberr_t*	err,	/*!< out: this is set to DB_ERROR if an error
				was encountered, otherwise not changed */
	const char*	dirname,/*!< in: directory name or path */
	os_file_dir_t	dir,	/*!< in: directory stream */
	os_file_stat_t*	info)	/*!< in/out: buffer where the
				info is returned */
{
	for (ulint i = 0; i < 100; i++) {
		int	ret = os_file_readdir_next_file(dirname, dir, info);

		if (ret != -1) {

			return(ret);
		}

		ib::error() << "os_file_readdir_next_file() returned -1 in"
			" directory " << dirname
			<< ", crash recovery may have failed"
			" for some .ibd files!";

		*err = DB_ERROR;
	}

	return(-1);
}

/** Try to adjust FSP_SPACE_FLAGS if they differ from the expectations.
(Typically when upgrading from MariaDB 10.1.0..10.1.20.)
@param[in,out]	space		tablespace
@param[in]	flags		desired tablespace flags */
void fsp_flags_try_adjust(fil_space_t* space, ulint flags)
{
	ut_ad(!srv_read_only_mode);
	ut_ad(fil_space_t::is_valid_flags(flags, space->id));
	if (space->full_crc32() || fil_space_t::full_crc32(flags)) {
		return;
	}
	if (!space->size && (space->purpose != FIL_TYPE_TABLESPACE
			     || !fil_space_get_size(space->id))) {
		return;
	}
	/* This code is executed during server startup while no
	connections are allowed. We do not need to protect against
	DROP TABLE by fil_space_acquire(). */
	mtr_t	mtr;
	mtr.start();
	if (buf_block_t* b = buf_page_get(
		    page_id_t(space->id, 0), space->zip_size(),
		    RW_X_LATCH, &mtr)) {
		ulint f = fsp_header_get_flags(b->frame);
		if (fil_space_t::full_crc32(f)) {
			goto func_exit;
		}
		if (fil_space_t::is_flags_equal(f, flags)) {
			goto func_exit;
		}
		/* Suppress the message if only the DATA_DIR flag to differs. */
		if ((f ^ flags) & ~(1U << FSP_FLAGS_POS_RESERVED)) {
			ib::warn()
				<< "adjusting FSP_SPACE_FLAGS of file '"
				<< UT_LIST_GET_FIRST(space->chain)->name
				<< "' from " << ib::hex(f)
				<< " to " << ib::hex(flags);
		}
		mtr.set_named_space(space);
		mtr.write<4>(*b, FSP_HEADER_OFFSET + FSP_SPACE_FLAGS
			     + b->frame, flags);
	}
func_exit:
	mtr.commit();
}

/** Determine if a matching tablespace exists in the InnoDB tablespace
memory cache. Note that if we have not done a crash recovery at the database
startup, there may be many tablespaces which are not yet in the memory cache.
@param[in]	id		Tablespace ID
@param[in]	name		Tablespace name used in fil_space_create().
@param[in]	table_flags	table flags
@return the tablespace
@retval	NULL	if no matching tablespace exists in the memory cache */
fil_space_t*
fil_space_for_table_exists_in_mem(
	ulint		id,
	const char*	name,
	ulint		table_flags)
{
	const ulint	expected_flags = dict_tf_to_fsp_flags(table_flags);

	mutex_enter(&fil_system.mutex);
	if (fil_space_t* space = fil_space_get_by_id(id)) {
		ulint tf = expected_flags & ~FSP_FLAGS_MEM_MASK;
		ulint sf = space->flags & ~FSP_FLAGS_MEM_MASK;

		if (!fil_space_t::is_flags_equal(tf, sf)
		    && !fil_space_t::is_flags_equal(sf, tf)) {
			goto func_exit;
		}

		if (strcmp(space->name, name)) {
			ib::error() << "Table " << name
				<< " in InnoDB data dictionary"
				" has tablespace id " << id
				<< ", but the tablespace"
				" with that id has name " << space->name << "."
				" Have you deleted or moved .ibd files?";
			ib::info() << TROUBLESHOOT_DATADICT_MSG;
			goto func_exit;
		}

		/* Adjust the flags that are in FSP_FLAGS_MEM_MASK.
		FSP_SPACE_FLAGS will not be written back here. */
		space->flags = (space->flags & ~FSP_FLAGS_MEM_MASK)
			| (expected_flags & FSP_FLAGS_MEM_MASK);
		mutex_exit(&fil_system.mutex);
		if (!srv_read_only_mode) {
			fsp_flags_try_adjust(space, expected_flags
					     & ~FSP_FLAGS_MEM_MASK);
		}
		return space;
	}

func_exit:
	mutex_exit(&fil_system.mutex);
	return NULL;
}

/*============================ FILE I/O ================================*/

/********************************************************************//**
NOTE: you must call fil_mutex_enter_and_prepare_for_io() first!

Prepares a file node for i/o. Opens the file if it is closed. Updates the
pending i/o's field in the node and the system appropriately. Takes the node
off the LRU list if it is in the LRU list. The caller must hold the fil_sys
mutex.
@return false if the file can't be opened, otherwise true */
static
bool
fil_node_prepare_for_io(
/*====================*/
	fil_node_t*	node,	/*!< in: file node */
	fil_space_t*	space)	/*!< in: space */
{
	ut_ad(node && space);
	ut_ad(mutex_own(&fil_system.mutex));

	if (fil_system.n_open > srv_max_n_open_files + 5) {
		ib::warn() << "Open files " << fil_system.n_open
			<< " exceeds the limit " << srv_max_n_open_files;
	}

	if (!node->is_open()) {
		/* File is closed: open it */
		ut_a(node->n_pending == 0);

		if (!fil_node_open_file(node)) {
			return(false);
		}
	}

	if (node->n_pending++ == 0 && fil_space_belongs_in_lru(space)) {
		UT_LIST_REMOVE(fil_system.LRU, node);
	}

	return(true);
}

/** Report information about an invalid page access. */
ATTRIBUTE_COLD __attribute__((noreturn))
static void
fil_report_invalid_page_access(const page_id_t id, const char *name,
                               ulint byte_offset, ulint len, bool is_read)
{
	ib::fatal()
		<< "Trying to " << (is_read ? "read " : "write ")
		<< id
		<< " which is outside the bounds of tablespace " << name
		<< ". Byte offset " << byte_offset << ", len " << len;
}

inline void IORequest::set_fil_node(fil_node_t* node)
{
	if (!node->space->punch_hole) {
		clear_punch_hole();
	}

	m_fil_node = node;
}

/** Reads or writes data. This operation could be asynchronous (aio).

@param[in,out] type	IO context
@param[in] sync		true if synchronous aio is desired
@param[in] page_id	page id
@param[in] zip_size	ROW_FORMAT=COMPRESSED page size, or 0
@param[in] byte_offset	remainder of offset in bytes; in aio this
			must be divisible by the OS block size
@param[in] len		how many bytes to read or write; this must
			not cross a file boundary; in aio this must
			be a block size multiple
@param[in,out] buf	buffer where to store read data or from where
			to write; in aio this must be appropriately
			aligned
@param[in] message	message for aio handler if non-sync aio
			used, else ignored
@param[in] ignore	whether to ignore errors
@param[in] punch_hole	punch the hole to the file for page_compressed
			tablespace
@return status and file descriptor */
fil_io_t
fil_io(
	const IORequest&	type,
	bool			sync,
	const page_id_t		page_id,
	ulint			zip_size,
	ulint			byte_offset,
	ulint			len,
	void*			buf,
	void*			message,
	bool			ignore,
	bool			punch_hole)
{
	os_offset_t		offset;
	IORequest		req_type(type);

	ut_ad(req_type.validate());

	ut_ad(len > 0);
	ut_ad(byte_offset < srv_page_size);
	ut_ad(!zip_size || byte_offset == 0);
	ut_ad(srv_page_size == 1UL << srv_page_size_shift);
	compile_time_assert((1U << UNIV_PAGE_SIZE_SHIFT_MAX)
			    == UNIV_PAGE_SIZE_MAX);
	compile_time_assert((1U << UNIV_PAGE_SIZE_SHIFT_MIN)
			    == UNIV_PAGE_SIZE_MIN);
	ut_ad(fil_validate_skip());

	/* ibuf bitmap pages must be read in the sync AIO mode: */
	ut_ad(recv_no_ibuf_operations
	      || req_type.is_write()
	      || !ibuf_bitmap_page(page_id, zip_size)
	      || sync);

	ulint	mode;

	if (sync) {
		mode = OS_AIO_SYNC;
	} else if (req_type.is_read()
		   && !recv_no_ibuf_operations
		   && ibuf_page(page_id, zip_size, NULL)) {
		mode = OS_AIO_IBUF;
	} else {
		mode = OS_AIO_NORMAL;
	}

	if (req_type.is_read()) {

		srv_stats.data_read.add(len);

	} else if (req_type.is_write()) {

		ut_ad(!srv_read_only_mode
		      || fsp_is_system_temporary(page_id.space()));

		srv_stats.data_written.add(len);
	}

	/* Acquire fil_system.mutex and make sure that we can open at
	least one file while holding it, if the file is not already open */
	fil_space_t*	space = fil_mutex_enter_and_prepare_for_io(
		page_id.space());

	if (!space
	    || (req_type.is_read()
		&& !sync
		&& space->stop_new_ops
		&& !space->is_being_truncated)) {

		mutex_exit(&fil_system.mutex);
		if (!ignore) {
			ib::error()
				<< "Trying to do I/O to a tablespace which"
				" does not exist. I/O type: "
				<< (req_type.is_read() ? "read" : "write")
				<< ", page: " << page_id
				<< ", I/O length: " << len << " bytes";
		}

		return {DB_TABLESPACE_DELETED, nullptr};
	}

	ulint		cur_page_no = page_id.page_no();
	fil_node_t*	node = UT_LIST_GET_FIRST(space->chain);

	for (;;) {

		if (node == NULL) {
			if (ignore) {
				mutex_exit(&fil_system.mutex);
				return {DB_ERROR, nullptr};
			}

			fil_report_invalid_page_access(
				page_id, space->name, byte_offset, len,
				req_type.is_read());

		} else if (fil_is_user_tablespace_id(space->id)
			   && node->size == 0) {

			/* We do not know the size of a single-table tablespace
			before we open the file */
			break;

		} else if (node->size > cur_page_no) {
			/* Found! */
			break;

		} else {
			cur_page_no -= node->size;

			node = UT_LIST_GET_NEXT(chain, node);
		}
	}

	/* Open file if closed */
	if (UNIV_UNLIKELY(!fil_node_prepare_for_io(node, space))) {
		ut_ad(fil_is_user_tablespace_id(space->id));
		mutex_exit(&fil_system.mutex);

		if (!ignore) {
			ib::error()
				<< "Trying to do I/O to a tablespace '"
				<< space->name
				<< "' which exists without .ibd data file."
				" I/O type: "
				<< (req_type.is_read()
				    ? "read" : "write")
				<< ", page: "
				<< page_id
				<< ", I/O length: " << len << " bytes";
		}

		return {DB_TABLESPACE_DELETED, nullptr};
	}

	if (node->size <= cur_page_no) {
		if (ignore) {
			/* If we can tolerate the non-existent pages, we
			should return with DB_ERROR and let caller decide
			what to do. */
			node->complete_io(req_type.is_write());
			mutex_exit(&fil_system.mutex);
			return {DB_ERROR, nullptr};
		}

		fil_report_invalid_page_access(
			page_id, space->name, byte_offset, len,
			req_type.is_read());
	}

	space->acquire_for_io();
	/* Now we have made the changes in the data structures of fil_system */
	mutex_exit(&fil_system.mutex);

	if (!zip_size) zip_size = srv_page_size;

	offset = os_offset_t(cur_page_no) * zip_size + byte_offset;
	ut_ad(node->size - cur_page_no >= (len + (zip_size - 1)) / zip_size);

	/* Do AIO */

	ut_a(byte_offset % OS_FILE_LOG_BLOCK_SIZE == 0);
	ut_a((len % OS_FILE_LOG_BLOCK_SIZE) == 0);

	const char* name = node->name == NULL ? space->name : node->name;

	req_type.set_fil_node(node);

	ut_ad(!req_type.is_write()
	      || !fil_is_user_tablespace_id(page_id.space())
	      || offset == page_id.page_no() * zip_size);

	dberr_t err = DB_SUCCESS;

	if (punch_hole) {
		/* Punch the hole to the file */
		err = os_file_punch_hole(node->handle, offset, len);
	} else {
		/* Queue the aio request */
		err = os_aio(
			req_type,
			mode, name, node->handle, buf, offset, len,
			space->purpose != FIL_TYPE_TEMPORARY
			&& srv_read_only_mode,
			node, message);
	}

	/* We an try to recover the page from the double write buffer if
	the decompression fails or the page is corrupt. */

	ut_a(req_type.is_dblwr_recover() || err == DB_SUCCESS);
	if (sync) {
		mutex_enter(&fil_system.mutex);
		node->complete_io(req_type.is_write());
		mutex_exit(&fil_system.mutex);
		ut_ad(fil_validate_skip());
	}
	return {err, node};
}

#include <tpool.h>

/** Callback for AIO completion */
void fil_aio_callback(os_aio_userdata_t *data)
{
  ut_ad(fil_validate_skip());

  fil_node_t *node= data->node;

  if (UNIV_UNLIKELY(!node))
  {
    ut_ad(srv_shutdown_state == SRV_SHUTDOWN_EXIT_THREADS);
    return;
  }

  ut_ad(data->type.validate());

  buf_page_t *bpage= static_cast<buf_page_t*>(data->message);
  if (!bpage)
  {
    /* Asynchronous single page writes from the doublewrite buffer
    don't have access to the page. */
    ut_ad(data->type.is_write());
    ut_ad(node->space == fil_system.sys_space);
    ut_ad(!srv_read_only_mode);
write_completed:
    mutex_enter(&fil_system.mutex);
    node->complete_io(true);
    mutex_exit(&fil_system.mutex);
    node->space->release_for_io();
    return;
  }

  if (data->type.is_write())
  {
    ut_ad(!srv_read_only_mode || node->space->purpose == FIL_TYPE_TEMPORARY);
    bool dblwr= node->space->use_doublewrite();
    if (dblwr && bpage->status == buf_page_t::INIT_ON_FLUSH)
    {
      bpage->status= buf_page_t::NORMAL;
      dblwr= false;
    }
    buf_page_write_complete(bpage, data->type, dblwr, false);
    goto write_completed;
  }

  ut_ad(data->type.is_read());

  /* IMPORTANT: since i/o handling for reads will read also the insert
  buffer in fil_system.sys_space, we have to be very careful not to
  introduce deadlocks. We never close the system tablespace (0) data
  files via fil_system.LRU and we use a dedicated I/O thread to serve
  change buffer requests. */
  const page_id_t id(bpage->id());

  if (dberr_t err= buf_page_read_complete(bpage, *node))
  {
    if (recv_recovery_is_on() && !srv_force_recovery)
      recv_sys.found_corrupt_fs= true;

    ib::error() << "Failed to read page " << id.page_no()
                << " from file '" << node->name << "': "
                << ut_strerr(err);
  }

  mutex_enter(&fil_system.mutex);
  node->complete_io();
  mutex_exit(&fil_system.mutex);
  node->space->release_for_io();
}

/**********************************************************************//**
Flushes to disk possible writes cached by the OS. If the space does not exist
or is being dropped, does not do anything. */
void
fil_flush(
/*======*/
	ulint	space_id)	/*!< in: file space id (this can be a group of
				log files or a tablespace of the database) */
{
	mutex_enter(&fil_system.mutex);

	if (fil_space_t* space = fil_space_get_by_id(space_id)) {
		if (space->purpose != FIL_TYPE_TEMPORARY
		    && !space->is_stopping()) {
			fil_flush_low(space);
		}
	}

	mutex_exit(&fil_system.mutex);
}

/** Flush a tablespace.
@param[in,out]	space	tablespace to flush */
void
fil_flush(fil_space_t* space)
{
	ut_ad(space->pending_io());
	ut_ad(space->purpose == FIL_TYPE_TABLESPACE
	      || space->purpose == FIL_TYPE_IMPORT);

	if (!space->is_stopping()) {
		mutex_enter(&fil_system.mutex);
		if (!space->is_stopping()) {
			fil_flush_low(space);
		}
		mutex_exit(&fil_system.mutex);
	}
}

/** Flush to disk the writes in file spaces of the given type
possibly cached by the OS. */
void fil_flush_file_spaces()
{
	ulint*		space_ids;
	ulint		n_space_ids;

	mutex_enter(&fil_system.mutex);

	n_space_ids = fil_system.unflushed_spaces.size();
	if (n_space_ids == 0) {

		mutex_exit(&fil_system.mutex);
		return;
	}

	space_ids = static_cast<ulint*>(
		ut_malloc_nokey(n_space_ids * sizeof(*space_ids)));

	n_space_ids = 0;

	for (sized_ilist<fil_space_t, unflushed_spaces_tag_t>::iterator it
	     = fil_system.unflushed_spaces.begin(),
	     end = fil_system.unflushed_spaces.end();
	     it != end; ++it) {

		if (it->purpose == FIL_TYPE_TABLESPACE && !it->is_stopping()) {
			space_ids[n_space_ids++] = it->id;
		}
	}

	mutex_exit(&fil_system.mutex);

	/* Flush the spaces.  It will not hurt to call fil_flush() on
	a non-existing space id. */
	for (ulint i = 0; i < n_space_ids; i++) {

		fil_flush(space_ids[i]);
	}

	ut_free(space_ids);
}

/** Functor to validate the file node list of a tablespace. */
struct	Check {
	/** Total size of file nodes visited so far */
	ulint	size;
	/** Total number of open files visited so far */
	ulint	n_open;

	/** Constructor */
	Check() : size(0), n_open(0) {}

	/** Visit a file node
	@param[in]	elem	file node to visit */
	void	operator()(const fil_node_t* elem)
	{
		ut_a(elem->is_open() || !elem->n_pending);
		n_open += elem->is_open();
		size += elem->size;
	}

	/** Validate a tablespace.
	@param[in]	space	tablespace to validate
	@return		number of open file nodes */
	static ulint validate(const fil_space_t* space)
	{
		ut_ad(mutex_own(&fil_system.mutex));
		Check	check;
		ut_list_validate(space->chain, check);
		ut_a(space->size == check.size);
		ut_ad(space->id != TRX_SYS_SPACE
		      || space == fil_system.sys_space);
		ut_ad(space->id != SRV_TMP_SPACE_ID
		      || space == fil_system.temp_space);
		return(check.n_open);
	}
};

/******************************************************************//**
Checks the consistency of the tablespace cache.
@return true if ok */
bool fil_validate()
{
	fil_space_t*	space;
	fil_node_t*	fil_node;
	ulint		n_open		= 0;

	mutex_enter(&fil_system.mutex);

	/* Look for spaces in the hash table */

	for (ulint i = 0; i < hash_get_n_cells(fil_system.spaces); i++) {

		for (space = static_cast<fil_space_t*>(
				HASH_GET_FIRST(fil_system.spaces, i));
		     space != 0;
		     space = static_cast<fil_space_t*>(
				HASH_GET_NEXT(hash, space))) {

			n_open += Check::validate(space);
		}
	}

	ut_a(fil_system.n_open == n_open);

	ut_list_validate(fil_system.LRU);

	for (fil_node = UT_LIST_GET_FIRST(fil_system.LRU);
	     fil_node != 0;
	     fil_node = UT_LIST_GET_NEXT(LRU, fil_node)) {

		ut_a(fil_node->n_pending == 0);
		ut_a(!fil_node->being_extended);
		ut_a(fil_node->is_open());
		ut_a(fil_space_belongs_in_lru(fil_node->space));
	}

	mutex_exit(&fil_system.mutex);

	return(true);
}

/*********************************************************************//**
Sets the file page type. */
void
fil_page_set_type(
/*==============*/
	byte*	page,	/*!< in/out: file page */
	ulint	type)	/*!< in: type */
{
	ut_ad(page);

	mach_write_to_2(page + FIL_PAGE_TYPE, type);
}

/********************************************************************//**
Delete the tablespace file and any related files like .cfg.
This should not be called for temporary tables.
@param[in] ibd_filepath File path of the IBD tablespace */
void
fil_delete_file(
/*============*/
	const char*	ibd_filepath)
{
	/* Force a delete of any stale .ibd files that are lying around. */

	ib::info() << "Deleting " << ibd_filepath;
	os_file_delete_if_exists(innodb_data_file_key, ibd_filepath, NULL);

	char*	cfg_filepath = fil_make_filepath(
		ibd_filepath, NULL, CFG, false);
	if (cfg_filepath != NULL) {
		os_file_delete_if_exists(
			innodb_data_file_key, cfg_filepath, NULL);
		ut_free(cfg_filepath);
	}
}

#ifdef UNIV_DEBUG
/** Check that a tablespace is valid for mtr_commit().
@param[in]	space	persistent tablespace that has been changed */
static
void
fil_space_validate_for_mtr_commit(
	const fil_space_t*	space)
{
	ut_ad(!mutex_own(&fil_system.mutex));
	ut_ad(space != NULL);
	ut_ad(space->purpose == FIL_TYPE_TABLESPACE);
	ut_ad(!is_predefined_tablespace(space->id));

	/* We are serving mtr_commit(). While there is an active
	mini-transaction, we should have !space->stop_new_ops. This is
	guaranteed by meta-data locks or transactional locks, or
	dict_sys.latch (X-lock in DROP, S-lock in purge). */
	ut_ad(!space->stop_new_ops
	      || space->is_being_truncated /* fil_truncate_prepare() */
	      || space->referenced());
}
#endif /* UNIV_DEBUG */

/** Write a FILE_MODIFY record for a persistent tablespace.
@param[in]	space	tablespace
@param[in,out]	mtr	mini-transaction */
static
void
fil_names_write(
	const fil_space_t*	space,
	mtr_t*			mtr)
{
	ut_ad(UT_LIST_GET_LEN(space->chain) == 1);
	fil_name_write(space->id, UT_LIST_GET_FIRST(space->chain)->name, mtr);
}

/** Note that a non-predefined persistent tablespace has been modified
by redo log.
@param[in,out]	space	tablespace */
void
fil_names_dirty(
	fil_space_t*	space)
{
	ut_ad(log_mutex_own());
	ut_ad(recv_recovery_is_on());
	ut_ad(log_sys.get_lsn() != 0);
	ut_ad(space->max_lsn == 0);
	ut_d(fil_space_validate_for_mtr_commit(space));

	UT_LIST_ADD_LAST(fil_system.named_spaces, space);
	space->max_lsn = log_sys.get_lsn();
}

/** Write FILE_MODIFY records when a non-predefined persistent
tablespace was modified for the first time since the latest
fil_names_clear().
@param[in,out]	space	tablespace */
void fil_names_dirty_and_write(fil_space_t* space)
{
	ut_ad(log_mutex_own());
	ut_d(fil_space_validate_for_mtr_commit(space));
	ut_ad(space->max_lsn == log_sys.get_lsn());

	UT_LIST_ADD_LAST(fil_system.named_spaces, space);
	mtr_t mtr;
	mtr.start();
	fil_names_write(space, &mtr);

	DBUG_EXECUTE_IF("fil_names_write_bogus",
			{
				char bogus_name[] = "./test/bogus file.ibd";
				os_normalize_path(bogus_name);
				fil_name_write(
					SRV_SPACE_ID_UPPER_BOUND,
					bogus_name, &mtr);
			});

	mtr.commit_files();
}

/** On a log checkpoint, reset fil_names_dirty_and_write() flags
and write out FILE_MODIFY and FILE_CHECKPOINT if needed.
@param[in]	lsn		checkpoint LSN
@param[in]	do_write	whether to always write FILE_CHECKPOINT
@return whether anything was written to the redo log
@retval false	if no flags were set and nothing written
@retval true	if anything was written to the redo log */
bool
fil_names_clear(
	lsn_t	lsn,
	bool	do_write)
{
	mtr_t	mtr;
	ulint	mtr_checkpoint_size = RECV_SCAN_SIZE - 1;

	DBUG_EXECUTE_IF(
		"increase_mtr_checkpoint_size",
		mtr_checkpoint_size = 75 * 1024;
		);

	ut_ad(log_mutex_own());
	ut_ad(lsn);

	mtr.start();

	for (fil_space_t* space = UT_LIST_GET_FIRST(fil_system.named_spaces);
	     space != NULL; ) {
		if (mtr.get_log()->size()
		    + (3 + 5 + 1) + strlen(space->chain.start->name)
		    >= mtr_checkpoint_size) {
			/* Prevent log parse buffer overflow */
			mtr.commit_files();
			mtr.start();
		}

		fil_space_t*	next = UT_LIST_GET_NEXT(named_spaces, space);

		ut_ad(space->max_lsn > 0);
		if (space->max_lsn < lsn) {
			/* The tablespace was last dirtied before the
			checkpoint LSN. Remove it from the list, so
			that if the tablespace is not going to be
			modified any more, subsequent checkpoints will
			avoid calling fil_names_write() on it. */
			space->max_lsn = 0;
			UT_LIST_REMOVE(fil_system.named_spaces, space);
		}

		/* max_lsn is the last LSN where fil_names_dirty_and_write()
		was called. If we kept track of "min_lsn" (the first LSN
		where max_lsn turned nonzero), we could avoid the
		fil_names_write() call if min_lsn > lsn. */

		fil_names_write(space, &mtr);
		do_write = true;

		space = next;
	}

	if (do_write) {
		mtr.commit_files(lsn);
	} else {
		ut_ad(!mtr.has_modifications());
	}

	return(do_write);
}

/* Unit Tests */
#ifdef UNIV_ENABLE_UNIT_TEST_MAKE_FILEPATH
#define MF  fil_make_filepath
#define DISPLAY ib::info() << path
void
test_make_filepath()
{
	char* path;
	const char* long_path =
		"this/is/a/very/long/path/including/a/very/"
		"looooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooooo"
		"oooooooooooooooooooooooooooooooooooooooooooooooong"
		"/folder/name";
	path = MF("/this/is/a/path/with/a/filename", NULL, IBD, false); DISPLAY;
	path = MF("/this/is/a/path/with/a/filename", NULL, ISL, false); DISPLAY;
	path = MF("/this/is/a/path/with/a/filename", NULL, CFG, false); DISPLAY;
	path = MF("/this/is/a/path/with/a/filename.ibd", NULL, IBD, false); DISPLAY;
	path = MF("/this/is/a/path/with/a/filename.ibd", NULL, IBD, false); DISPLAY;
	path = MF("/this/is/a/path/with/a/filename.dat", NULL, IBD, false); DISPLAY;
	path = MF(NULL, "tablespacename", NO_EXT, false); DISPLAY;
	path = MF(NULL, "tablespacename", IBD, false); DISPLAY;
	path = MF(NULL, "dbname/tablespacename", NO_EXT, false); DISPLAY;
	path = MF(NULL, "dbname/tablespacename", IBD, false); DISPLAY;
	path = MF(NULL, "dbname/tablespacename", ISL, false); DISPLAY;
	path = MF(NULL, "dbname/tablespacename", CFG, false); DISPLAY;
	path = MF(NULL, "dbname\\tablespacename", NO_EXT, false); DISPLAY;
	path = MF(NULL, "dbname\\tablespacename", IBD, false); DISPLAY;
	path = MF("/this/is/a/path", "dbname/tablespacename", IBD, false); DISPLAY;
	path = MF("/this/is/a/path", "dbname/tablespacename", IBD, true); DISPLAY;
	path = MF("./this/is/a/path", "dbname/tablespacename.ibd", IBD, true); DISPLAY;
	path = MF("this\\is\\a\\path", "dbname/tablespacename", IBD, true); DISPLAY;
	path = MF("/this/is/a/path", "dbname\\tablespacename", IBD, true); DISPLAY;
	path = MF(long_path, NULL, IBD, false); DISPLAY;
	path = MF(long_path, "tablespacename", IBD, false); DISPLAY;
	path = MF(long_path, "tablespacename", IBD, true); DISPLAY;
}
#endif /* UNIV_ENABLE_UNIT_TEST_MAKE_FILEPATH */
/* @} */

/** Return the next fil_space_t.
Once started, the caller must keep calling this until it returns NULL.
fil_space_t::acquire() and fil_space_t::release() are invoked here which
blocks a concurrent operation from dropping the tablespace.
@param[in]	prev_space	Pointer to the previous fil_space_t.
If NULL, use the first fil_space_t on fil_system.space_list.
@return pointer to the next fil_space_t.
@retval NULL if this was the last*/
fil_space_t*
fil_space_next(fil_space_t* prev_space)
{
	fil_space_t*		space=prev_space;

	mutex_enter(&fil_system.mutex);

	if (!space) {
		space = UT_LIST_GET_FIRST(fil_system.space_list);
	} else {
		ut_a(space->referenced());

		/* Move on to the next fil_space_t */
		space->release();
		space = UT_LIST_GET_NEXT(space_list, space);
	}

	/* Skip spaces that are being created by
	fil_ibd_create(), or dropped, or !tablespace. */
	while (space != NULL
	       && (UT_LIST_GET_LEN(space->chain) == 0
		   || space->is_stopping()
		   || space->purpose != FIL_TYPE_TABLESPACE)) {
		space = UT_LIST_GET_NEXT(space_list, space);
	}

	if (space != NULL) {
		space->acquire();
	}

	mutex_exit(&fil_system.mutex);

	return(space);
}

/**
Remove space from key rotation list if there are no more
pending operations.
@param[in,out]	space		Tablespace */
static
void
fil_space_remove_from_keyrotation(fil_space_t* space)
{
	ut_ad(mutex_own(&fil_system.mutex));
	ut_ad(space);

	if (!space->referenced() && space->is_in_rotation_list) {
		space->is_in_rotation_list = false;
		ut_a(!fil_system.rotation_list.empty());
		fil_system.rotation_list.remove(*space);
	}
}


/** Return the next fil_space_t from key rotation list.
Once started, the caller must keep calling this until it returns NULL.
fil_space_t::acquire() and fil_space_t::release() are invoked here which
blocks a concurrent operation from dropping the tablespace.
@param[in]	prev_space	Pointer to the previous fil_space_t.
If NULL, use the first fil_space_t on fil_system.space_list.
@param[in]	recheck		recheck of the tablespace is needed or
				still encryption thread does write page0 for it
@param[in]	key_version	key version of the key state thread
@return pointer to the next fil_space_t.
@retval NULL if this was the last */
fil_space_t *fil_system_t::keyrotate_next(fil_space_t *prev_space,
                                          bool recheck, uint key_version)
{
  mutex_enter(&fil_system.mutex);

  /* If one of the encryption threads already started the encryption
  of the table then don't remove the unencrypted spaces from rotation list

  If there is a change in innodb_encrypt_tables variables value then
  don't remove the last processed tablespace from the rotation list. */
  const bool remove= (!recheck || prev_space->crypt_data) &&
                     !key_version == !srv_encrypt_tables;
  sized_ilist<fil_space_t, rotation_list_tag_t>::iterator it=
    prev_space ? prev_space : fil_system.rotation_list.end();

  if (it == fil_system.rotation_list.end())
    it= fil_system.rotation_list.begin();
  else
  {
    /* Move on to the next fil_space_t */
    prev_space->release();

    ++it;

    while (it != fil_system.rotation_list.end() &&
           (UT_LIST_GET_LEN(it->chain) == 0 || it->is_stopping()))
      ++it;

    if (remove)
      fil_space_remove_from_keyrotation(prev_space);
  }

  fil_space_t *space= it == fil_system.rotation_list.end() ? NULL : &*it;

  if (space)
    space->acquire();

  mutex_exit(&fil_system.mutex);
  return space;
}

/** Determine the block size of the data file.
@param[in]	space		tablespace
@param[in]	offset		page number
@return	block size */
UNIV_INTERN
ulint
fil_space_get_block_size(const fil_space_t* space, unsigned offset)
{
	ulint block_size = 512;

	for (fil_node_t* node = UT_LIST_GET_FIRST(space->chain);
	     node != NULL;
	     node = UT_LIST_GET_NEXT(chain, node)) {
		block_size = node->block_size;
		if (node->size > offset) {
			ut_ad(node->size <= 0xFFFFFFFFU);
			break;
		}
		offset -= static_cast<unsigned>(node->size);
	}

	/* Currently supporting block size up to 4K,
	fall back to default if bigger requested. */
	if (block_size > 4096) {
		block_size = 512;
	}

	return block_size;
}

/*******************************************************************//**
Returns the table space by a given id, NULL if not found. */
fil_space_t*
fil_space_found_by_id(
/*==================*/
	ulint	id)	/*!< in: space id */
{
	fil_space_t* space = NULL;
	mutex_enter(&fil_system.mutex);
	space = fil_space_get_by_id(id);

	/* Not found if space is being deleted */
	if (space && space->stop_new_ops) {
		space = NULL;
	}

	mutex_exit(&fil_system.mutex);
	return space;
}