MDEV-381: fdatasync() does not correctly flush growing binlog file

Revert the old work-around for buggy fdatasync() on Linux ext3. This bug was
fixed in Linux > 10 years ago back to kernel version at least 3.0.

Reviewed-by: Marko Mäkelä <marko.makela@mariadb.com>
Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

include/my_sys.h

@@ -92,7 +92,6 @@ typedef struct my_aio_result {
 #define MY_THREADSAFE 2048U     /* my_seek(): lock fd mutex */
 #define MY_SYNC       4096U     /* my_copy(): sync dst file */
 #define MY_SYNC_DIR   32768U    /* my_create/delete/rename: sync directory */
-#define MY_SYNC_FILESIZE 65536U /* my_sync(): safe sync when file is extended */
 #define MY_THREAD_SPECIFIC 0x10000U /* my_malloc(): thread specific */
 #define MY_THREAD_MOVE     0x20000U /* realloc(); Memory can move */
 /* Tree that should delete things automatically */

mysys/my_sync.c

@@ -49,13 +49,6 @@ void thr_set_sync_wait_callback(void (*before_wait)(void),
     (which is correct behaviour, if we know that the other thread synced the
     file before closing)
 
-    MY_SYNC_FILESIZE is useful when syncing a file after it has been extended.
-    On Linux, fdatasync() on ext3/ext4 file systems does not properly flush
-    to disk the inode data required to preserve the added data across a crash
-    (this looks to be a bug). But when a file is extended, inode data will most
-    likely need flushing in any case, so passing MY_SYNC_FILESIZE as flags
-    is not likely to be any slower, and will be crash safe on Linux ext3/ext4.
-
   RETURN
     0 ok
     -1 error
@@ -88,12 +81,8 @@ int my_sync(File fd, myf my_flags)
     DBUG_PRINT("info",("fcntl(F_FULLFSYNC) failed, falling back"));
 #endif
 #if defined(HAVE_FDATASYNC) && HAVE_DECL_FDATASYNC
-    if (!(my_flags & MY_SYNC_FILESIZE))
+    res= fdatasync(fd);
-      res= fdatasync(fd);
+#elif defined(HAVE_FSYNC)
-    else
-    {
-#endif
-#if defined(HAVE_FSYNC)
     res= fsync(fd);
     if (res == -1 && errno == ENOLCK)
       res= 0;                                   /* Result Bug in Old FreeBSD */
@@ -102,9 +91,6 @@ int my_sync(File fd, myf my_flags)
 #else
 #error Cannot find a way to sync a file, durability in danger
     res= 0;					/* No sync (strange OS) */
-#endif
-#if defined(HAVE_FDATASYNC) && HAVE_DECL_FDATASYNC
-    }
 #endif
   } while (res == -1 && errno == EINTR);
 

sql/backup.cc

@@ -311,8 +311,7 @@ static bool backup_block_commit(THD *thd)
   if (mysql_bin_log.is_open())
   {
     mysql_mutex_lock(mysql_bin_log.get_log_lock());
-    mysql_file_sync(mysql_bin_log.get_log_file()->file,
+    mysql_file_sync(mysql_bin_log.get_log_file()->file, MYF(MY_WME));
-                    MYF(MY_WME|MY_SYNC_FILESIZE));
     mysql_mutex_unlock(mysql_bin_log.get_log_lock());
   }
   thd->clear_error();

sql/log.cc

@@ -3730,7 +3730,7 @@ bool MYSQL_BIN_LOG::open(const char *log_name,
       bytes_written+= description_event_for_queue->data_written;
     }
     if (flush_io_cache(&log_file) ||
-        mysql_file_sync(log_file.file, MYF(MY_WME|MY_SYNC_FILESIZE)))
+        mysql_file_sync(log_file.file, MYF(MY_WME)))
       goto err;
 
     my_off_t offset= my_b_tell(&log_file);
@@ -3768,7 +3768,7 @@ bool MYSQL_BIN_LOG::open(const char *log_name,
                      strlen(log_file_name)) ||
           my_b_write(&index_file, (uchar*) "\n", 1) ||
           flush_io_cache(&index_file) ||
-          mysql_file_sync(index_file.file, MYF(MY_WME|MY_SYNC_FILESIZE)))
+          mysql_file_sync(index_file.file, MYF(MY_WME)))
         goto err;
 
 #ifdef HAVE_REPLICATION
@@ -3908,7 +3908,7 @@ static bool copy_up_file_and_fill(IO_CACHE *index_file, my_off_t offset)
   }
   /* The following will either truncate the file or fill the end with \n' */
   if (mysql_file_chsize(file, offset - init_offset, '\n', MYF(MY_WME)) ||
-      mysql_file_sync(file, MYF(MY_WME|MY_SYNC_FILESIZE)))
+      mysql_file_sync(file, MYF(MY_WME)))
     goto err;
 
   /* Reset data in old index cache */
@@ -4702,7 +4702,7 @@ int MYSQL_BIN_LOG::sync_purge_index_file()
 
   if (unlikely((error= flush_io_cache(&purge_index_file))) ||
       unlikely((error= my_sync(purge_index_file.file,
-                               MYF(MY_WME | MY_SYNC_FILESIZE)))))
+                               MYF(MY_WME)))))
     DBUG_RETURN(error);
 
   DBUG_RETURN(error);
@@ -5462,7 +5462,7 @@ bool MYSQL_BIN_LOG::flush_and_sync(bool *synced)
   if (sync_period && ++sync_counter >= sync_period)
   {
     sync_counter= 0;
-    err= mysql_file_sync(fd, MYF(MY_WME|MY_SYNC_FILESIZE));
+    err= mysql_file_sync(fd, MYF(MY_WME));
     if (synced)
       *synced= 1;
 #ifndef DBUG_OFF
@@ -6142,7 +6142,7 @@ MYSQL_BIN_LOG::write_state_to_file()
   log_inited= false;
   if ((err= end_io_cache(&cache)))
     goto err;
-  if ((err= mysql_file_sync(file_no, MYF(MY_WME|MY_SYNC_FILESIZE))))
+  if ((err= mysql_file_sync(file_no, MYF(MY_WME))))
     goto err;
   goto end;