MDEV-32163 Crash recovery fails after DROP TABLE in system tablespace

fseg_free_extent(): After fsp_free_extent() succeeded, properly
mark the affected pages as freed. We failed to write FREE_PAGE records.

This bug was revealed or caused by
commit e938d7c1 (MDEV-32028).

mysql-test/suite/innodb/r/scrub.result

+SET GLOBAL
+innodb_file_per_table=OFF,
+innodb_purge_rseg_truncate_frequency=1,
+innodb_immediate_scrub_data_uncompressed=ON;
+CREATE TABLE t1(f1 INT NOT NULL, f2 INT NOT NULL,
+f3 INT NOT NULL, INDEX(f1),
+INDEX(f2), INDEX(f3))ENGINE=InnoDB;
+INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
+INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
+INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
+DROP TABLE t1;
+SET GLOBAL innodb_max_purge_lag_wait=0;
+# restart

mysql-test/suite/innodb/t/scrub.test

+--source include/have_innodb.inc
+--source include/have_sequence.inc
+--source include/not_embedded.inc
+
+SET GLOBAL
+  innodb_file_per_table=OFF,
+  innodb_purge_rseg_truncate_frequency=1,
+  innodb_immediate_scrub_data_uncompressed=ON;
+CREATE TABLE t1(f1 INT NOT NULL, f2 INT NOT NULL,
+                f3 INT NOT NULL, INDEX(f1),
+                INDEX(f2), INDEX(f3))ENGINE=InnoDB;
+INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
+INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
+INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
+DROP TABLE t1;
+SET GLOBAL innodb_max_purge_lag_wait=0;
+# The crash recovery would occasionally fail.
+let $shutdown_timeout=0;
+--source include/restart_mysqld.inc

storage/innobase/fsp/fsp0fsp.cc

@@ -2683,14 +2683,23 @@ fseg_free_extent(
 			      not_full_n_used - descr_n_used);
 	}
 
+	std::vector<uint8_t> going_to_free;
+	static_assert(FSP_EXTENT_SIZE_MIN == 256, "compatibility");
+	static_assert(FSP_EXTENT_SIZE_MAX == 64, "compatibility");
+
 	for (uint32_t i = 0; i < FSP_EXTENT_SIZE; i++) {
 		if (!xdes_is_free(descr, i)) {
-			buf_page_free(space, first_page_in_extent + i, mtr,
-				      __FILE__, __LINE__);
+			going_to_free.emplace_back(uint8_t(i));
 		}
 	}
 
 	fsp_free_extent(space, page, mtr);
+
+	for (uint32_t i : going_to_free) {
+		mtr->free(*space, first_page_in_extent + i);
+		buf_page_free(space, first_page_in_extent + i, mtr,
+			      __FILE__, __LINE__);
+	}
 }
 
 /**********************************************************************//**