Bug#27261822 - EMPTY GENERAL TABLESPACE CRASHES UPGRADE

Problem:
-------
Upgrade with empty general tablespace (no CREATE TABLE using
general tablespace), crashes the upgrade to 8.0

This is because we assumed the initial number of pages of an
5.7 IBD file to be 6. This is true for file_per_table tablespaces.
Size of freshly created tablespace is 4 and we expect minimum
6 pages. Hence the assert.

Fix:
----
Use the right mininum size of IBD file as 4 pages.

Reviewed-By: Sunny Bains <[email protected]>
Approved on IM

Author: satya461

storage/innobase/include/fil0fil.h

@@ -784,7 +784,11 @@ extern Fil_path	MySQL_datadir_path;
 
 /** Initial size of a single-table tablespace in pages */
 constexpr size_t	FIL_IBD_FILE_INITIAL_SIZE = 7;
-constexpr size_t	FIL_IBD_FILE_INITIAL_SIZE_5_7 = 6;
+
+/** An empty tablespace (CREATE TABLESPACE) has minimum
+of 4 pages and an empty CREATE TABLE (file_per_table) has 6 pages.
+Minimum of these two is 4 */
+constexpr size_t	FIL_IBD_FILE_INITIAL_SIZE_5_7 = 4;
 
 /** 'null' (undefined) page offset in the context of file spaces */
 constexpr page_no_t	FIL_NULL = std::numeric_limits<page_no_t>::max();