TSAN: data race on a global counter

WARNING: ThreadSanitizer: data race (pid=1503350)
  Write of size 8 at 0x0000067b1f20 by thread T3:
    #0 os_file_sync_posix(int) /storage/innobase/os/os0file.cc:895:5 (mariadbd+0x23493f6)
    #1 os_file_flush_func(int) /storage/innobase/os/os0file.cc:983:8 (mariadbd+0x2349204)
    #2 file_os_io::flush() /storage/innobase/log/log0log.cc:326:10 (mariadbd+0x22eaaa9)
    #3 log_file_t::flush() /storage/innobase/log/log0log.cc:440:18 (mariadbd+0x22eb2d0)
    #4 log_t::file::flush() /storage/innobase/log/log0log.cc:507:29 (mariadbd+0x22ebe69)
    #5 log_write_flush_to_disk_low(unsigned long) /storage/innobase/log/log0log.cc:629:17 (mariadbd+0x22ed3f3)
    #6 log_write_up_to(unsigned long, bool, bool, completion_callback const*) /storage/innobase/log/log0log.cc:829:3 (mariadbd+0x22ecb04)
    #7 log_checkpoint_low(unsigned long, unsigned long) /storage/innobase/buf/buf0flu.cc:1734:5 (mariadbd+0x20d37f1)
    MariaDB#8 buf_flush_sync_for_checkpoint(unsigned long) /storage/innobase/buf/buf0flu.cc:1947:7 (mariadbd+0x20d4193)
    MariaDB#9 buf_flush_page_cleaner() /storage/innobase/buf/buf0flu.cc:2186:9 (mariadbd+0x20cdad7)
    MariaDB#10 void std::__invoke_impl<void, void (*)()>(std::__invoke_other, void (*&&)()) /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/invoke.h:61:14 (mariadbd+0x20c3aaa)
    MariaDB#11 std::__invoke_result<void (*)()>::type std::__invoke<void (*)()>(void (*&&)()) /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/invoke.h:96:14 (mariadbd+0x20c39bd)
    MariaDB#12 void std::thread::_Invoker<std::tuple<void (*)()> >::_M_invoke<0ul>(std::_Index_tuple<0ul>) /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/std_thread.h:253:13 (mariadbd+0x20c3965)
    MariaDB#13 std::thread::_Invoker<std::tuple<void (*)()> >::operator()() /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/std_thread.h:260:11 (mariadbd+0x20c3905)
    MariaDB#14 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (*)()> > >::_M_run() /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/std_thread.h:211:13 (mariadbd+0x20c37f9)
    MariaDB#15 <null> <null> (libstdc++.so.6+0xd230f)

  Previous write of size 8 at 0x0000067b1f20 by main thread:
    #0 os_file_sync_posix(int) /storage/innobase/os/os0file.cc:895:5 (mariadbd+0x23493f6)
    #1 os_file_flush_func(int) /storage/innobase/os/os0file.cc:983:8 (mariadbd+0x2349204)
    #2 fil_space_t::flush_low() /storage/innobase/fil/fil0fil.cc:504:5 (mariadbd+0x205cad5)
    #3 fil_flush_file_spaces() /storage/innobase/fil/fil0fil.cc:2947:13 (mariadbd+0x206523f)
    #4 log_checkpoint() /storage/innobase/buf/buf0flu.cc:1777:5 (mariadbd+0x20cd069)
    #5 buf_flush_wait_flushed(unsigned long) /storage/innobase/buf/buf0flu.cc:1867:5 (mariadbd+0x20ccf95)
    #6 log_make_checkpoint() /storage/innobase/buf/buf0flu.cc:1793:3 (mariadbd+0x20cc4c9)
    #7 buf_dblwr_t::create() /storage/innobase/buf/buf0dblwr.cc:216:3 (mariadbd+0x209076a)
    MariaDB#8 srv_start(bool) /storage/innobase/srv/srv0start.cc:1685:20 (mariadbd+0x256b514)
    MariaDB#9 innodb_init(void*) /storage/innobase/handler/ha_innodb.cc:4188:8 (mariadbd+0x1ed406a)
    MariaDB#10 ha_initialize_handlerton(st_plugin_int*) /sql/handler.cc:659:31 (mariadbd+0xf7c246)
    MariaDB#11 plugin_initialize(st_mem_root*, st_plugin_int*, int*, char**, bool) /sql/sql_plugin.cc:1463:9 (mariadbd+0x160fe6b)
    MariaDB#12 plugin_init(int*, char**, int) /sql/sql_plugin.cc:1756:15 (mariadbd+0x160f4cf)
    MariaDB#13 init_server_components() /sql/mysqld.cc:5043:7 (mariadbd+0xd713f2)
    MariaDB#14 mysqld_main(int, char**) /sql/mysqld.cc:5655:7 (mariadbd+0xd6ae17)
    MariaDB#15 main /sql/main.cc:34:10 (mariadbd+0xd66158)

This is a correct report by TSAN for an obvious case: unprotected global
counter. Fix it by making counter std::atomic.

Author: kevgs

storage/innobase/include/os0file.h

@@ -264,7 +264,7 @@ constexpr ulint OS_AIO_N_PENDING_IOS_PER_THREAD= 256;
 
 extern Atomic_counter<ulint> os_n_file_reads;
 extern ulint	os_n_file_writes;
-extern ulint	os_n_fsyncs;
+extern Atomic_counter<size_t> os_n_fsyncs;
 
 /* File types for directory entry data type */
 

storage/innobase/os/os0file.cc

@@ -158,7 +158,7 @@ static ulint	os_innodb_umask	= 0;
 Atomic_counter<ulint> os_n_file_reads;
 static ulint	os_bytes_read_since_printout;
 ulint	os_n_file_writes;
-ulint	os_n_fsyncs;
+Atomic_counter<size_t> os_n_fsyncs;
 static ulint	os_n_file_reads_old;
 static ulint	os_n_file_writes_old;
 static ulint	os_n_fsyncs_old;
@@ -3925,13 +3925,12 @@ os_aio_print(FILE*	file)
 		"Pending flushes (fsync) log: " ULINTPF
 		"; buffer pool: " ULINTPF "\n"
 		ULINTPF " OS file reads, "
-		ULINTPF " OS file writes, "
-		ULINTPF " OS fsyncs\n",
+		ULINTPF " OS file writes, %zu OS fsyncs\n",
 		log_sys.get_pending_flushes(),
 		ulint{fil_n_pending_tablespace_flushes},
 		ulint{os_n_file_reads},
 		os_n_file_writes,
-		os_n_fsyncs);
+		static_cast<size_t>(os_n_fsyncs));
 
 	const ulint n_reads = ulint(MONITOR_VALUE(MONITOR_OS_PENDING_READS));
 	const ulint n_writes = ulint(MONITOR_VALUE(MONITOR_OS_PENDING_WRITES));