branches/5.1:

Merge r2166:2168 from trunk/:

Bug#32440:

Put information about the free space in a tablespace in
INFORMATION_SCHEMA.TABLES.DATA_FREE. This information was previously
available in INFORMATION_SCHEMA.TABLES.TABLE_COMMENT, but MySQL has
removed it from there recently.

The stored value is in kilobytes.

This can be considered as a permanent workaround to
http://bugs.mysql.com/32440. "Workaround" becasue that bug is about the
data missing from TABLE_COMMENT and this is actually not solved.

handler/ha_innodb.cc

@@ -5726,7 +5726,9 @@ ha_innobase::info(
 		stats.index_file_length = ((ulonglong)
 				ib_table->stat_sum_of_other_index_sizes)
 					* UNIV_PAGE_SIZE;
-		stats.delete_length = 0;
+		stats.delete_length =
+			fsp_get_available_space_in_free_extents(
+				ib_table->space);
 		stats.check_time = 0;
 
 		if (stats.records == 0) {