Merge 10.1 into 10.2

storage/innobase/dict/dict0defrag_bg.cc

@@ -241,6 +241,7 @@ dict_stats_process_entry_from_defrag_pool(trx_t* trx)
 		return;
 	}
 
+	mutex_exit(&dict_sys->mutex);
 	++trx->will_lock;
 	dberr_t err = dict_stats_save_defrag_stats(index, trx);
 

storage/xtradb/dict/dict0stats_bg.cc

@@ -512,6 +512,7 @@ dict_stats_process_entry_from_defrag_pool()
 		return;
 	}
 
+	mutex_exit(&dict_sys->mutex);
 	dict_stats_save_defrag_stats(index);
 	dict_table_close(table, FALSE, FALSE);
 }