diff --git a/handler/ha_innodb.cc b/handler/ha_innodb.cc
index faab76010fc..aa54e0fa30e 100644
--- a/handler/ha_innodb.cc
+++ b/handler/ha_innodb.cc
@@ -1911,12 +1911,7 @@ retry:
 		trx->mysql_log_file_name = mysql_bin_log_file_name();
 		trx->mysql_log_offset = (ib_longlong) mysql_bin_log_file_pos();
 
-		/* Don't do write + flush right now. For group commit
-		to work we want to do the flush after releasing the
-		prepare_commit_mutex. */
-		trx->flush_log_later = TRUE;
 		innobase_commit_low(trx);
-		trx->flush_log_later = FALSE;
 
 		if (srv_commit_concurrency > 0) {
 			pthread_mutex_lock(&commit_cond_m);
@@ -1930,8 +1925,6 @@ retry:
 			pthread_mutex_unlock(&prepare_commit_mutex);
 		}
 
-		/* Now do a write + flush of logs. */
-		trx_commit_complete_for_mysql(trx);
 		trx->active_trans = 0;
 
 	} else {
@@ -7740,7 +7733,32 @@ innobase_xa_prepare(
 	int error = 0;
 	trx_t* trx = check_trx_exists(thd);
 
+	if (thd_sql_command(thd) != SQLCOM_XA_PREPARE &&
+	    (all || !thd_test_options(thd, OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))
+	{
 
+		/* For ibbackup to work the order of transactions in binlog
+		and InnoDB must be the same. Consider the situation
+
+		  thread1> prepare; write to binlog; ...
+			  <context switch>
+		  thread2> prepare; write to binlog; commit
+		  thread1>			     ... commit
+
+		To ensure this will not happen we're taking the mutex on
+		prepare, and releasing it on commit.
+
+		Note: only do it for normal commits, done via ha_commit_trans.
+		If 2pc protocol is executed by external transaction
+		coordinator, it will be just a regular MySQL client
+		executing XA PREPARE and XA COMMIT commands.
+		In this case we cannot know how many minutes or hours
+		will be between XA PREPARE and XA COMMIT, and we don't want
+		to block for undefined period of time.
+		*/
+		pthread_mutex_lock(&prepare_commit_mutex);
+		trx->active_trans = 2;
+	}
 
 	if (!THDVAR(thd, support_xa)) {
 
@@ -7793,33 +7811,6 @@ innobase_xa_prepare(
 
 	srv_active_wake_master_thread();
 
-	if (thd_sql_command(thd) != SQLCOM_XA_PREPARE &&
-	    (all || !thd_test_options(thd, OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))
-	{
-
-		/* For ibbackup to work the order of transactions in binlog
-		and InnoDB must be the same. Consider the situation
-
-		  thread1> prepare; write to binlog; ...
-			  <context switch>
-		  thread2> prepare; write to binlog; commit
-		  thread1>			     ... commit
-
-		To ensure this will not happen we're taking the mutex on
-		prepare, and releasing it on commit.
-
-		Note: only do it for normal commits, done via ha_commit_trans.
-		If 2pc protocol is executed by external transaction
-		coordinator, it will be just a regular MySQL client
-		executing XA PREPARE and XA COMMIT commands.
-		In this case we cannot know how many minutes or hours
-		will be between XA PREPARE and XA COMMIT, and we don't want
-		to block for undefined period of time.
-		*/
-		pthread_mutex_lock(&prepare_commit_mutex);
-		trx->active_trans = 2;
-	}
-
 	return(error);
 }
 
diff --git a/include/trx0trx.h b/include/trx0trx.h
index 505e540638a..7b107348f2b 100644
--- a/include/trx0trx.h
+++ b/include/trx0trx.h
@@ -461,12 +461,10 @@ struct trx_struct{
 					FALSE, one can save CPU time and about
 					150 bytes in the undo log size as then
 					we skip XA steps */
-	unsigned	flush_log_later:1;/* In 2PC, we hold the
-					prepare_commit mutex across
-					both phases. In that case, we
-					defer flush of the logs to disk
-					until after we release the
-					mutex. */
+	unsigned	flush_log_later:1;/* when we commit the transaction
+					in MySQL's binlog write, we will
+					flush the log to disk later in
+					a separate call */
 	unsigned	must_flush_log_later:1;/* this flag is set to TRUE in
 					trx_commit_off_kernel() if
 					flush_log_later was TRUE, and there
diff --git a/trx/trx0trx.c b/trx/trx0trx.c
index 6d29de92683..1213852fc5a 100644
--- a/trx/trx0trx.c
+++ b/trx/trx0trx.c
@@ -842,11 +842,11 @@ trx_commit_off_kernel(
 		there are > 2 users in the database. Then at least 2 users can
 		gather behind one doing the physical log write to disk.
 
-		If we are calling trx_commit() under prepare_commit_mutex, we
+		If we are calling trx_commit() under MySQL's binlog mutex, we
 		will delay possible log write and flush to a separate function
 		trx_commit_complete_for_mysql(), which is only called when the
-		thread has released the mutex. This is to make the
-		group commit algorithm to work. Otherwise, the prepare_commit
+		thread has released the binlog mutex. This is to make the
+		group commit algorithm to work. Otherwise, the MySQL binlog
 		mutex would serialize all commits and prevent a group of
 		transactions from gathering. */