MDEV-28779: ALTER TABLE IMPORT TABLESPACE corrupts an encrypted table

PageConverter::update_header(): Remove an unnecessary write.
The field that was originally called FIL_PAGE_FILE_FLUSH_LSN only
made sense for the first page of the system tablespace
(initially, for the first page of each file of the system tablespace).
It never had any meaning for .ibd files, and it lost its original
meaning in MariaDB Server 10.8.1 when
commit b07920b (MDEV-27199)
removed the ability to start without ib_logfile0.

If the most significant 32 bits of the LSN are nonzero, this
unnecessary write would write the wrong encryption key identifier
to the page. The first page of any file is never encrypted,
so normally those bytes should be 0 for any .ibd file.

mysql-test/suite/mariabackup/huge_lsn.result

@@ -2,7 +2,7 @@
 # MDEV-13416 mariabackup fails with EFAULT "Bad Address"
 #
 FOUND 1 /InnoDB: New log files created, LSN=175964\d{8}/ in mysqld.1.err
-CREATE TABLE t(i INT) ENGINE INNODB;
+CREATE TABLE t(i INT) ENGINE=INNODB ENCRYPTED=YES;
 INSERT INTO t VALUES(1);
 # xtrabackup backup
 SET GLOBAL innodb_flush_log_at_trx_commit=1;
@@ -15,6 +15,14 @@ INSERT INTO t VALUES(2);
 SELECT * FROM t;
 i
 1
+FLUSH TABLE t FOR EXPORT;
+UNLOCK TABLES;
+ALTER TABLE t DISCARD TABLESPACE;
+ALTER TABLE t IMPORT TABLESPACE;
+FLUSH TABLE t FOR EXPORT;
+UNLOCK TABLES;
+ALTER TABLE t DISCARD TABLESPACE;
+ALTER TABLE t IMPORT TABLESPACE;
 DROP TABLE t;
 # shutdown server
 # remove datadir

mysql-test/suite/mariabackup/huge_lsn.test

@@ -40,7 +40,7 @@ let SEARCH_FILE= $MYSQLTEST_VARDIR/log/mysqld.1.err;
 --let SEARCH_PATTERN= InnoDB: New log files created, LSN=175964\d{8}
 --source include/search_pattern_in_file.inc
 
-CREATE TABLE t(i INT) ENGINE INNODB;
+CREATE TABLE t(i INT) ENGINE=INNODB ENCRYPTED=YES;
 INSERT INTO t VALUES(1);
 
 echo # xtrabackup backup;
@@ -56,6 +56,22 @@ exec $XTRABACKUP  --prepare --target-dir=$targetdir;
 --source include/restart_and_restore.inc
 --enable_result_log
 SELECT * FROM t;
+FLUSH TABLE t FOR EXPORT;
+copy_file $_datadir/test/t.ibd $_datadir/test/t_copy.ibd;
+copy_file $_datadir/test/t.cfg $_datadir/test/t_copy.cfg;
+UNLOCK TABLES;
+ALTER TABLE t DISCARD TABLESPACE;
+move_file $_datadir/test/t_copy.ibd $_datadir/test/t.ibd;
+move_file $_datadir/test/t_copy.cfg $_datadir/test/t.cfg;
+ALTER TABLE t IMPORT TABLESPACE;
+FLUSH TABLE t FOR EXPORT;
+copy_file $_datadir/test/t.ibd $_datadir/test/t_copy.ibd;
+copy_file $_datadir/test/t.cfg $_datadir/test/t_copy.cfg;
+UNLOCK TABLES;
+ALTER TABLE t DISCARD TABLESPACE;
+move_file $_datadir/test/t_copy.ibd $_datadir/test/t.ibd;
+move_file $_datadir/test/t_copy.cfg $_datadir/test/t.cfg;
+ALTER TABLE t IMPORT TABLESPACE;
 DROP TABLE t;
 rmdir $targetdir;
 let $targetdir= $targetdir_old;

storage/innobase/row/row0import.cc

@@ -1,7 +1,7 @@
 /*****************************************************************************
 
 Copyright (c) 2012, 2016, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2015, 2021, MariaDB Corporation.
+Copyright (c) 2015, 2022, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -1996,10 +1996,6 @@ PageConverter::update_header(
 		ib::warn() << "Space id check in the header failed: ignored";
 	}
 
-	mach_write_to_8(
-		get_frame(block) + FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION,
-		m_current_lsn);
-
 	/* Write back the adjusted flags. */
 	mach_write_to_4(FSP_HEADER_OFFSET + FSP_SPACE_FLAGS
 			+ get_frame(block), m_space_flags);