Fix for bug #11762012 - "54553: INNODB ASSERTS IN

HA_INNOBASE::UPDATE_ROW, TEMPORARY TABLE, TABLE LOCK".

Attempt to update an InnoDB temporary table under LOCK TABLES
led to assertion failure in both debug and production builds
if this temporary table was explicitly locked for READ. The 
same scenario works fine for MyISAM temporary tables.

The assertion failure was caused by discrepancy between lock 
that was requested on the rows of temporary table at LOCK TABLES
time and by update operation. Since SQL-layer requested a 
read-lock at LOCK TABLES time InnoDB engine assumed that upcoming
statements which are going to be executed under LOCK TABLES will 
only read table and therefore should acquire only S-lock.
An update operation broken this assumption by requesting X-lock.

Possible approaches to fixing this problem are:

1) Skip locking of temporary tables as locking doesn't make any
   sense for connection-local objects.
2) Prohibit changing of temporary table locked by LOCK TABLES ... 
   READ.

Unfortunately both of these approaches have drawbacks which make 
them unviable for stable versions of server.

So this patch takes another approach and changes code in such way
that LOCK TABLES for a temporary table will always request write
lock. In 5.1 version of this patch switch from read lock to write
lock is done inside of InnoDBs handler methods as doing it on 
SQL-layer causes compatibility troubles with FLUSH TABLES WITH
READ LOCK.

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

@@ -2639,7 +2639,6 @@ COUNT(*)
 1537
 SET SESSION sort_buffer_size = DEFAULT;
 DROP TABLE t1;
-End of 5.1 tests
 #
 # Test for bug #39932 "create table fails if column for FK is in different
 #                      case than in corr index".
@@ -2668,3 +2667,20 @@ DROP TABLE IF EXISTS t1, t2;
 CREATE TABLE t1 (a INT, INDEX(a)) engine=innodb;
 ALTER TABLE t1 RENAME TO t2, DISABLE KEYS;
 DROP TABLE IF EXISTS t1, t2;
+#
+# Test for bug #11762012 - "54553: INNODB ASSERTS IN HA_INNOBASE::
+#                           UPDATE_ROW, TEMPORARY TABLE, TABLE LOCK".
+#
+DROP TABLE IF EXISTS t1;
+CREATE TEMPORARY TABLE t1 (c int) ENGINE = InnoDB;
+INSERT INTO t1 VALUES (1);
+LOCK TABLES t1 READ;
+# Even though temporary table was locked for READ we
+# still allow writes to it to be compatible with MyISAM.
+# This is possible since due to fact that temporary tables
+# are specific to connection and therefore locking for them
+# is irrelevant.
+UPDATE t1 SET c = 5;
+UNLOCK TABLES;
+DROP TEMPORARY TABLE t1;
+End of 5.1 tests

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

@@ -868,9 +868,6 @@ SET SESSION sort_buffer_size = DEFAULT;
 DROP TABLE t1;
 
 
---echo End of 5.1 tests
-
-
 --echo #
 --echo # Test for bug #39932 "create table fails if column for FK is in different
 --echo #                      case than in corr index".
@@ -900,3 +897,25 @@ CREATE TABLE t1 (a INT, INDEX(a)) engine=innodb;
 ALTER TABLE t1 RENAME TO t2, DISABLE KEYS;
 DROP TABLE IF EXISTS t1, t2;
 --enable_warnings
+
+
+--echo #
+--echo # Test for bug #11762012 - "54553: INNODB ASSERTS IN HA_INNOBASE::
+--echo #                           UPDATE_ROW, TEMPORARY TABLE, TABLE LOCK".
+--echo #
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+CREATE TEMPORARY TABLE t1 (c int) ENGINE = InnoDB;
+INSERT INTO t1 VALUES (1);
+LOCK TABLES t1 READ;
+--echo # Even though temporary table was locked for READ we
+--echo # still allow writes to it to be compatible with MyISAM.
+--echo # This is possible since due to fact that temporary tables
+--echo # are specific to connection and therefore locking for them
+--echo # is irrelevant.
+UPDATE t1 SET c = 5;
+UNLOCK TABLES;
+DROP TEMPORARY TABLE t1;
+
+--echo End of 5.1 tests

mysql-test/suite/innodb_plugin/r/innodb_mysql.result

@@ -2438,4 +2438,20 @@ COUNT(*)
 1537
 SET SESSION sort_buffer_size = DEFAULT;
 DROP TABLE t1;
+#
+# Test for bug #11762012 - "54553: INNODB ASSERTS IN HA_INNOBASE::
+#                           UPDATE_ROW, TEMPORARY TABLE, TABLE LOCK".
+#
+DROP TABLE IF EXISTS t1;
+CREATE TEMPORARY TABLE t1 (c int) ENGINE = InnoDB;
+INSERT INTO t1 VALUES (1);
+LOCK TABLES t1 READ;
+# Even though temporary table was locked for READ we
+# still allow writes to it to be compatible with MyISAM.
+# This is possible since due to fact that temporary tables
+# are specific to connection and therefore locking for them
+# is irrelevant.
+UPDATE t1 SET c = 5;
+UNLOCK TABLES;
+DROP TEMPORARY TABLE t1;
 End of 5.1 tests

mysql-test/suite/innodb_plugin/t/innodb_mysql.test

@@ -689,4 +689,24 @@ SET SESSION sort_buffer_size = DEFAULT;
 
 DROP TABLE t1;
 
+
+--echo #
+--echo # Test for bug #11762012 - "54553: INNODB ASSERTS IN HA_INNOBASE::
+--echo #                           UPDATE_ROW, TEMPORARY TABLE, TABLE LOCK".
+--echo #
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+CREATE TEMPORARY TABLE t1 (c int) ENGINE = InnoDB;
+INSERT INTO t1 VALUES (1);
+LOCK TABLES t1 READ;
+--echo # Even though temporary table was locked for READ we
+--echo # still allow writes to it to be compatible with MyISAM.
+--echo # This is possible since due to fact that temporary tables
+--echo # are specific to connection and therefore locking for them
+--echo # is irrelevant.
+UPDATE t1 SET c = 5;
+UNLOCK TABLES;
+DROP TEMPORARY TABLE t1;
+
 --echo End of 5.1 tests

storage/innobase/handler/ha_innodb.cc

@@ -7325,10 +7325,18 @@ ha_innobase::external_lock(
 
 	reset_template(prebuilt);
 
-	if (lock_type == F_WRLCK) {
+	if (lock_type == F_WRLCK
+	    || (table->s->tmp_table
+		&& thd_sql_command(thd) == SQLCOM_LOCK_TABLES)) {
 
 		/* If this is a SELECT, then it is in UPDATE TABLE ...
-		or SELECT ... FOR UPDATE */
+		or SELECT ... FOR UPDATE
+
+		For temporary tables which are locked for READ by LOCK TABLES
+		updates are still allowed by SQL-layer. In order to accomodate
+		for such a situation we always request X-lock for such table
+		at LOCK TABLES time.
+		*/
 		prebuilt->select_lock_type = LOCK_X;
 		prebuilt->stored_select_lock_type = LOCK_X;
 	}

storage/innodb_plugin/handler/ha_innodb.cc

@@ -8642,10 +8642,18 @@ ha_innobase::external_lock(
 
 	reset_template(prebuilt);
 
-	if (lock_type == F_WRLCK) {
+	if (lock_type == F_WRLCK
+	    || (table->s->tmp_table
+		&& thd_sql_command(thd) == SQLCOM_LOCK_TABLES)) {
 
 		/* If this is a SELECT, then it is in UPDATE TABLE ...
-		or SELECT ... FOR UPDATE */
+		or SELECT ... FOR UPDATE
+
+		For temporary tables which are locked for READ by LOCK TABLES
+		updates are still allowed by SQL-layer. In order to accomodate
+		for such a situation we always request X-lock for such table
+		at LOCK TABLES time.
+		*/
 		prebuilt->select_lock_type = LOCK_X;
 		prebuilt->stored_select_lock_type = LOCK_X;
 	}