branches/5.1:

Fix Bug#39438 Testcase for Bug#39436 crashes on 5.1 in fil_space_get_latch

In ha_innobase::info() - do not try to get the free space for a tablespace
which has been discarded with ALTER TABLE ... DISCARD TABLESPACE or if the
.ibd file is missing for some other reason.

ibd_file_missing and tablespace_discarded are manipulated only in
row_discard_tablespace_for_mysql() and in row_import_tablespace_for_mysql()
and the manipulation is protected/surrounded by
row_mysql_lock_data_dictionary()/row_mysql_unlock_data_dictionary() thus we
do the same in ha_innobase::info() when checking the values of those members
to avoid race conditions. I have tested the code-path with UNIV_DEBUG and
UNIV_SYNC_DEBUG.

Looks like it is not possible to avoid mysqld printing warnings in the
mysql-test case and thus this test innodb_bug39438 must be added to the
list of exceptional test cases that are allowed to print warnings. For this,
the following patch must be applied to the mysql source tree:

  --- cut ---
  === modified file 'mysql-test/lib/mtr_report.pl'
  --- mysql-test/lib/mtr_report.pl	2008-08-12 10:26:23 +0000
  +++ mysql-test/lib/mtr_report.pl	2008-10-01 11:57:41 +0000
  @@ -412,7 +412,10 @@
   
                   # When trying to set lower_case_table_names = 2
                   # on a case sensitive file system. Bug#37402.
  -                /lower_case_table_names was set to 2, even though your the file system '.*' is case sensitive.  Now setting lower_case_table_names to 0 to avoid future problems./
  +                /lower_case_table_names was set to 2, even though your the file system '.*' is case sensitive.  Now setting lower_case_table_names to 0 to avoid future problems./ or
  +
  +                # this test is expected to print warnings
  +                ($testname eq 'main.innodb_bug39438')
   		)
               {
                 next;                       # Skip these lines
  
  --- cut ---

The mysql-test is currently somewhat disabled (see inside
innodb_bug39438.test), after the above patch has been applied to the mysql
source tree, the test can be enabled.

rb://20

Reviewed by:	Inaam, Calvin
Approved by:	Heikki

handler/ha_innodb.cc

@@ -5865,9 +5865,24 @@ ha_innobase::info(
 		so the "old" value can remain. delete_length is initialized
 		to 0 in the ha_statistics' constructor. */
 		if (!(flag & HA_STATUS_NO_LOCK)) {
+
+			/* lock the data dictionary to avoid races with
+			ibd_file_missing and tablespace_discarded */
+			row_mysql_lock_data_dictionary(prebuilt->trx);
+
+			/* ib_table->space must be an existent tablespace */
+			if (!ib_table->ibd_file_missing
+			    && !ib_table->tablespace_discarded) {
+
 				stats.delete_length =
 					fsp_get_available_space_in_free_extents(
 						ib_table->space) * 1024;
+			} else {
+
+				stats.delete_length = 0;
+			}
+
+			row_mysql_unlock_data_dictionary(prebuilt->trx);
 		}
 
 		stats.check_time = 0;

mysql-test/innodb_bug39438-master.opt

+--innodb-file-per-table=1

mysql-test/innodb_bug39438.result

+SET storage_engine=InnoDB;

mysql-test/innodb_bug39438.test

+#
+# Bug#39438 Testcase for Bug#39436 crashes on 5.1 in fil_space_get_latch
+# http://bugs.mysql.com/39438
+#
+# This test must be run with innodb_file_per_table=1 because the crash
+# only occurs if that option is turned on and DISCARD TABLESPACE only
+# works with innodb_file_per_table.
+#
+
+-- source include/have_innodb.inc
+
+SET storage_engine=InnoDB;
+
+# we care only that the following SQL commands do not crash the server
+-- disable_query_log
+-- disable_result_log
+
+DROP TABLE IF EXISTS bug39438;
+
+CREATE TABLE bug39438 (id INT) ENGINE=INNODB;
+
+# remove: XXX Uncomment the following ALTER and remove those lines after
+# remove: applying the patch.
+# remove: Obviously this test is useless without this ALTER command,
+# remove: but it causes warnings to be printed by mysqld and the whole
+# remove: mysql-test suite fails at the end (returns non-zero). Please
+# remove: apply this patch to the mysql source tree, remove those lines
+# remove: and uncomment the following ALTER. We do not care about the
+# remove: warnings, this test is to ensure mysqld does not crash.
+# remove: === modified file 'mysql-test/lib/mtr_report.pl'
+# remove: --- mysql-test/lib/mtr_report.pl	2008-08-12 10:26:23 +0000
+# remove: +++ mysql-test/lib/mtr_report.pl	2008-10-01 11:57:41 +0000
+# remove: @@ -412,7 +412,10 @@
+# remove:  
+# remove:                  # When trying to set lower_case_table_names = 2
+# remove:                  # on a case sensitive file system. Bug#37402.
+# remove: -                /lower_case_table_names was set to 2, even though your the file system '.*' is case sensitive.  Now setting lower_case_table_names to 0 to avoid future problems./
+# remove: +                /lower_case_table_names was set to 2, even though your the file system '.*' is case sensitive.  Now setting lower_case_table_names to 0 to avoid future problems./ or
+# remove: +
+# remove: +                # this test is expected to print warnings
+# remove: +                ($testname eq 'main.innodb_bug39438')
+# remove:  		)
+# remove:              {
+# remove:                next;                       # Skip these lines
+# remove: 
+#ALTER TABLE bug39438 DISCARD TABLESPACE;
+
+# this crashes the server if the bug is present
+SHOW TABLE STATUS;
+
+DROP TABLE bug39438;