Bug#11758196 : INNODB ASSERTION FAILURE WHEN CONVERTING FROM MYISAM TO INNODB

Changed to try to extend log buffer instead of crash, when log size is too large for the size.

Approved by Marko in rb#3229

storage/innobase/include/log0log.h

@@ -809,6 +809,8 @@ struct log_struct{
 					later; this is advanced when a flush
 					operation is completed to all the log
 					groups */
+	volatile ibool	is_extending;	/*!< this is set to true during extend
+					the log buffer size */
 	ib_uint64_t	written_to_some_lsn;
 					/*!< first log sequence number not yet
 					written to any log group; for this to

storage/innobase/log/log0log.c

@@ -213,6 +213,84 @@ log_buf_pool_get_oldest_modification(void)
 	return(lsn);
 }
 
+/** Extends the log buffer.
+@param[in] len	requested minimum size in bytes */
+static
+void
+log_buffer_extend(
+	ulint	len)
+{
+	ulint	move_start;
+	ulint	move_end;
+	byte	tmp_buf[OS_FILE_LOG_BLOCK_SIZE];
+
+	mutex_enter(&(log_sys->mutex));
+
+	while (log_sys->is_extending) {
+		/* Another thread is trying to extend already.
+		Needs to wait for. */
+		mutex_exit(&(log_sys->mutex));
+
+		log_buffer_flush_to_disk();
+
+		mutex_enter(&(log_sys->mutex));
+
+		if (srv_log_buffer_size > len / UNIV_PAGE_SIZE) {
+			/* Already extended enough by the others */
+			mutex_exit(&(log_sys->mutex));
+			return;
+		}
+	}
+
+	log_sys->is_extending = TRUE;
+
+	while (log_sys->n_pending_writes != 0
+	       || ut_calc_align_down(log_sys->buf_free,
+				     OS_FILE_LOG_BLOCK_SIZE)
+		  != ut_calc_align_down(log_sys->buf_next_to_write,
+					OS_FILE_LOG_BLOCK_SIZE)) {
+		/* Buffer might have >1 blocks to write still. */
+		mutex_exit(&(log_sys->mutex));
+
+		log_buffer_flush_to_disk();
+
+		mutex_enter(&(log_sys->mutex));
+	}
+
+	move_start = ut_calc_align_down(
+		log_sys->buf_free,
+		OS_FILE_LOG_BLOCK_SIZE);
+	move_end = log_sys->buf_free;
+
+	/* store the last log block in buffer */
+	ut_memcpy(tmp_buf, log_sys->buf + move_start,
+		  move_end - move_start);
+
+	log_sys->buf_free -= move_start;
+	log_sys->buf_next_to_write -= move_start;
+
+	/* reallocate log buffer */
+	srv_log_buffer_size = len / UNIV_PAGE_SIZE + 1;
+	mem_free(log_sys->buf_ptr);
+	log_sys->buf_ptr = mem_alloc(LOG_BUFFER_SIZE + OS_FILE_LOG_BLOCK_SIZE);
+	log_sys->buf = ut_align(log_sys->buf_ptr, OS_FILE_LOG_BLOCK_SIZE);
+	log_sys->buf_size = LOG_BUFFER_SIZE;
+	log_sys->max_buf_free = log_sys->buf_size / LOG_BUF_FLUSH_RATIO
+		- LOG_BUF_FLUSH_MARGIN;
+
+	/* restore the last log block */
+	ut_memcpy(log_sys->buf, tmp_buf, move_end - move_start);
+
+	ut_ad(log_sys->is_extending);
+	log_sys->is_extending = FALSE;
+
+	mutex_exit(&(log_sys->mutex));
+
+	fprintf(stderr,
+		"InnoDB: innodb_log_buffer_size was extended to %lu.\n",
+		LOG_BUFFER_SIZE);
+}
+
 /************************************************************//**
 Opens the log for log_write_low. The log must be closed with log_close and
 released with log_release.
@@ -233,11 +311,39 @@ log_reserve_and_open(
 	ulint	count			= 0;
 #endif /* UNIV_DEBUG */
 
-	ut_a(len < log->buf_size / 2);
+	if (len >= log->buf_size / 2) {
+		DBUG_EXECUTE_IF("ib_log_buffer_is_short_crash",
+				DBUG_SUICIDE(););
+
+		/* log_buffer is too small. try to extend instead of crash. */
+		ut_print_timestamp(stderr);
+		fprintf(stderr,
+			" InnoDB: Warning: "
+			"The transaction log size is too large"
+			" for innodb_log_buffer_size (%lu >= %lu / 2). "
+			"Trying to extend it.\n",
+			len, LOG_BUFFER_SIZE);
+
+		log_buffer_extend((len + 1) * 2);
+	}
 loop:
 	mutex_enter(&(log->mutex));
 	ut_ad(!recv_no_log_write);
 
+	if (log->is_extending) {
+
+		mutex_exit(&(log->mutex));
+
+		/* Log buffer size is extending. Writing up to the next block
+		should wait for the extending finished. */
+
+		os_thread_sleep(100000);
+
+		ut_ad(++count < 50);
+
+		goto loop;
+	}
+
 	/* Calculate an upper limit for the space the string may take in the
 	log buffer */
 
@@ -788,6 +894,7 @@ log_init(void)
 	log_sys->buf = ut_align(log_sys->buf_ptr, OS_FILE_LOG_BLOCK_SIZE);
 
 	log_sys->buf_size = LOG_BUFFER_SIZE;
+	log_sys->is_extending = FALSE;
 
 	memset(log_sys->buf, '\0', LOG_BUFFER_SIZE);