MDEV-11687 innodb_use_fallocate has no effect

The configuration parameter innodb_use_fallocate, which is mapped to
the variable srv_use_posix_fallocate, has no effect in MariaDB 10.2.2
or MariaDB 10.2.3.
Thus the configuration parameter and the variable should be removed.

mysql-test/suite/sys_vars/r/innodb_use_fallocate_basic.result

-select @@global.innodb_use_fallocate;
-@@global.innodb_use_fallocate
-0
-select @@session.innodb_use_fallocate;
-ERROR HY000: Variable 'innodb_use_fallocate' is a GLOBAL variable
-show global variables like 'innodb_use_fallocate';
-Variable_name	Value
-innodb_use_fallocate	OFF
-show session variables like 'innodb_use_fallocate';
-Variable_name	Value
-innodb_use_fallocate	OFF
-select * from information_schema.global_variables where variable_name='innodb_use_fallocate';
-VARIABLE_NAME	VARIABLE_VALUE
-INNODB_USE_FALLOCATE	OFF
-select * from information_schema.session_variables where variable_name='innodb_use_fallocate';
-VARIABLE_NAME	VARIABLE_VALUE
-INNODB_USE_FALLOCATE	OFF
-set global innodb_use_fallocate=1;
-ERROR HY000: Variable 'innodb_use_fallocate' is a read only variable
-set session innodb_use_fallocate=1;
-ERROR HY000: Variable 'innodb_use_fallocate' is a read only variable

mysql-test/suite/sys_vars/r/sysvars_innodb.result

@@ -2581,20 +2581,6 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	OFF,ON
 READ_ONLY	YES
 COMMAND_LINE_ARGUMENT	NONE
-VARIABLE_NAME	INNODB_USE_FALLOCATE
-SESSION_VALUE	NULL
-GLOBAL_VALUE	OFF
-GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	OFF
-VARIABLE_SCOPE	GLOBAL
-VARIABLE_TYPE	BOOLEAN
-VARIABLE_COMMENT	Preallocate files fast, using operating system functionality. On POSIX systems, posix_fallocate system call is used.
-NUMERIC_MIN_VALUE	NULL
-NUMERIC_MAX_VALUE	NULL
-NUMERIC_BLOCK_SIZE	NULL
-ENUM_VALUE_LIST	OFF,ON
-READ_ONLY	YES
-COMMAND_LINE_ARGUMENT	NONE
 VARIABLE_NAME	INNODB_USE_MTFLUSH
 SESSION_VALUE	NULL
 GLOBAL_VALUE	OFF

mysql-test/suite/sys_vars/t/innodb_use_fallocate_basic.test

---source include/have_innodb.inc
-# bool readonly
-
-#
-# show values;
-#
-select @@global.innodb_use_fallocate;
---error ER_INCORRECT_GLOBAL_LOCAL_VAR
-select @@session.innodb_use_fallocate;
-show global variables like 'innodb_use_fallocate';
-show session variables like 'innodb_use_fallocate';
-select * from information_schema.global_variables where variable_name='innodb_use_fallocate';
-select * from information_schema.session_variables where variable_name='innodb_use_fallocate';
-
-#
-# show that it's read-only
-#
---error ER_INCORRECT_GLOBAL_LOCAL_VAR
-set global innodb_use_fallocate=1;
---error ER_INCORRECT_GLOBAL_LOCAL_VAR
-set session innodb_use_fallocate=1;
-

storage/innobase/handler/ha_innodb.cc

@@ -250,7 +250,6 @@ values */
 static ulong	innobase_fast_shutdown			= 1;
 static my_bool	innobase_file_format_check		= TRUE;
 static my_bool	innobase_use_atomic_writes		= FALSE;
-static my_bool	innobase_use_fallocate			= TRUE;
 static my_bool	innobase_use_doublewrite		= TRUE;
 static my_bool	innobase_use_checksums			= TRUE;
 static my_bool	innobase_locks_unsafe_for_binlog	= FALSE;
@@ -4637,9 +4636,6 @@ innobase_init(
 	data_mysql_default_charset_coll = (ulint) default_charset_info->number;
 
 	innobase_commit_concurrency_init_default();
-#ifdef HAVE_POSIX_FALLOCATE
-	srv_use_posix_fallocate = (ibool) innobase_use_fallocate;
-#endif
 	srv_use_atomic_writes = (ibool) innobase_use_atomic_writes;
 	if (innobase_use_atomic_writes) {
 		fprintf(stderr, "InnoDB: using atomic writes.\n");
@@ -4658,13 +4654,6 @@ innobase_init(
 				srv_file_flush_method_str = (char*)"O_DIRECT";
 			fprintf(stderr, "InnoDB: using O_DIRECT due to atomic writes.\n");
 		}
-#endif
-#ifdef HAVE_POSIX_FALLOCATE
-		/* Due to a bug in directFS, using atomics needs
-		 * posix_fallocate to extend the file
-		 * pwrite()  past end of the file won't work
-		 */
-		srv_use_posix_fallocate = TRUE;
 #endif
 	}
 
@@ -21957,11 +21946,6 @@ static MYSQL_SYSVAR_BOOL(use_atomic_writes, innobase_use_atomic_writes,
   "on Linux only with FusionIO device, and directFS filesystem.",
   NULL, NULL, FALSE);
 
-static MYSQL_SYSVAR_BOOL(use_fallocate, innobase_use_fallocate,
-  PLUGIN_VAR_NOCMDARG | PLUGIN_VAR_READONLY,
-  "Preallocate files fast, using operating system functionality. On POSIX systems, posix_fallocate system call is used.",
-  NULL, NULL, FALSE);
-
 static MYSQL_SYSVAR_ULONG(io_capacity, srv_io_capacity,
   PLUGIN_VAR_RQCMDARG,
   "Number of IOPs the server can do. Tunes the background IO rate",
@@ -23187,7 +23171,6 @@ static struct st_mysql_sys_var* innobase_system_variables[]= {
   MYSQL_SYSVAR(data_home_dir),
   MYSQL_SYSVAR(doublewrite),
   MYSQL_SYSVAR(use_atomic_writes),
-  MYSQL_SYSVAR(use_fallocate),
   MYSQL_SYSVAR(api_enable_binlog),
   MYSQL_SYSVAR(api_enable_mdl),
   MYSQL_SYSVAR(api_disable_rowlock),

storage/innobase/include/srv0srv.h

@@ -293,11 +293,6 @@ extern my_bool	srv_numa_interleave;
 /* Use trim operation */
 extern my_bool srv_use_trim;
 
-/* Use posix fallocate */
-#ifdef HAVE_POSIX_FALLOCATE
-extern my_bool srv_use_posix_fallocate;
-#endif
-
 /* Use atomic writes i.e disable doublewrite buffer */
 extern my_bool srv_use_atomic_writes;
 

storage/innobase/srv/srv0srv.cc

@@ -190,8 +190,6 @@ my_bool	srv_numa_interleave = FALSE;
 /* If this flag is TRUE, then we will use fallocate(PUCH_HOLE)
 to the pages */
 UNIV_INTERN my_bool	srv_use_trim = FALSE;
-/* If this flag is TRUE, then we will use posix fallocate for file extentsion */
-UNIV_INTERN my_bool	srv_use_posix_fallocate = FALSE;
 /* If this flag is TRUE, then we disable doublewrite buffer */
 UNIV_INTERN my_bool	srv_use_atomic_writes = FALSE;
 /* If this flag IS TRUE, then we use this algorithm for page compressing the pages */