BUG#25053705 INVALID I/O ON TABLE AFTER TRUNCATE

Issue:
======
The issue is that if a fts index is present in a table the space size is
incorrectly calculated in the case of truncate which results in a invalid
read.

Fix:
====
Have a different space size calculation in truncate if fts indexes are
present.

RB:14755
Reviewed-by: Shaohua Wang <shaohua.wang@oracle.com>

storage/innobase/buf/buf0rea.cc

 /*****************************************************************************
 
-Copyright (c) 1995, 2015, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2015, 2016 MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
@@ -290,6 +290,24 @@ buf_read_ahead_random(
 	below: if DISCARD + IMPORT changes the actual .ibd file meanwhile, we
 	do not try to read outside the bounds of the tablespace! */
 	if (fil_space_t* space = fil_space_acquire(page_id.space())) {
+
+#ifdef UNIV_DEBUG
+		if (srv_file_per_table) {
+			ulint	size = 0;
+
+			for (const fil_node_t*	node =
+				UT_LIST_GET_FIRST(space->chain);
+			     node != NULL;
+			     node = UT_LIST_GET_NEXT(chain, node)) {
+
+				size += os_file_get_size(node->handle)
+					/ page_size.logical();
+			}
+
+			ut_ad(size==space->size);
+		}
+#endif /* UNIV_DEBUG */
+
 		if (high > space->size) {
 			high = space->size;
 		}

storage/innobase/row/row0trunc.cc

@@ -2000,9 +2000,22 @@ row_truncate_table_for_mysql(
 	}
 
 	if (is_file_per_table && fsp_flags != ULINT_UNDEFINED) {
-		fil_reinit_space_header(
-			table->space,
-			table->indexes.count + FIL_IBD_FILE_INITIAL_SIZE + 1);
+		/* A single-table tablespace has initially
+		FIL_IBD_FILE_INITIAL_SIZE number of pages allocated and an
+		extra page is allocated for each of the indexes present. But in
+		the case of clust index 2 pages are allocated and as one is
+		covered in the calculation as part of table->indexes.count we
+		take care of the other page by adding 1. */
+		ulint	space_size = table->indexes.count +
+				FIL_IBD_FILE_INITIAL_SIZE + 1;
+
+		if (has_internal_doc_id) {
+			/* Since aux tables are created for fts indexes and
+			they use seperate tablespaces. */
+			space_size -= ib_vector_size(table->fts->indexes);
+		}
+
+		fil_reinit_space_header(table->space, space_size);
 	}
 
 	DBUG_EXECUTE_IF("ib_trunc_crash_with_intermediate_log_checkpoint",