From: Jon Olav Hauglid
Date: October 5 2010 10:25am
Subject: bzr commit into mysql-5.5-runtime branch (jon.hauglid:3153) Bug#57002
List-Archive: http://lists.mysql.com/commits/119975
X-Bug: 57002
Message-Id: <201010051027.o952RGoo029383@rcsinet13.oracle.com>
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="===============3323249975450233567=="

--===============3323249975450233567==
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

#At file:///export/home/x/mysql-5.5-runtime-bug57002/ based on revid:jon.hauglid@stripped

 3153 Jon Olav Hauglid	2010-10-05
      Bug #57002 Assert in upgrade_shared_lock_to_exclusive()
                 for ALTER TABLE + MERGE tables
      
      The patch for Bug#56292 changed how metadata locks are taken for MERGE
      tables. After the patch, locking the MERGE table will also lock the
      children tables with the same metadata lock type. This means that 
      LOCK TABLES on a MERGE table also will implicitly do LOCK TABLES on
      the children tables.
      
      A consequence of this change, is that it is possible to do LOCK TABLES
      on a child table both explicitly and implicitly with the same statement
      and that these two locks can be of different strength. For example,
      LOCK TABLES child READ, merge WRITE.
      
      In LOCK TABLES mode, we are not allowed to take new locks and each
      statement must therefore try to find an existing TABLE instance with
      a suitable lock. The code that searched for a suitable TABLE instance,
      only considered table level locks. If a child table was locked twice,
      it was therefore possible for this code to find a TABLE instance with
      suitable table level locks but without suitable metadata lock.
      
      This problem caused the assert in upgrade_shared_lock_to_exclusive()
      to be triggered as it tried to upgrade a MDL_SHARED lock to
      EXCLUSIVE. The problem was a regression caused by the patch for
      Bug#56292.
      
      This patch fixes the problem by partially reverting the changes
      done by Bug#56292. Now, the children tables will only use the
      same metadata lock as the MERGE table for MDL_SHARED_NO_WRITE
      when not in locked tables mode. This means that LOCK TABLE
      on a MERGE table will not implicitly lock the children tables.
      This still fixes the original problem in Bug#56292 without
      causing a regression.
      
      Test case added to merge.test.

    modified:
      mysql-test/r/merge.result
      mysql-test/t/merge.test
      storage/myisammrg/ha_myisammrg.cc
=== modified file 'mysql-test/r/merge.result'
--- a/mysql-test/r/merge.result	2010-09-30 10:43:43 +0000
+++ b/mysql-test/r/merge.result	2010-10-05 10:25:30 +0000
@@ -3486,12 +3486,13 @@ ALTER TABLE m1 ADD INDEX (c1);
 UNLOCK TABLES;
 DROP TABLE m1, t1;
 #
-# Locking the merge table will implicitly lock children.
+# Locking the merge table won't implicitly lock children.
 #
 CREATE TABLE t1 (c1 INT);
 CREATE TABLE m1 (c1 INT) ENGINE=MRG_MyISAM UNION=(t1);
 LOCK TABLE m1 WRITE;
 ALTER TABLE t1 ADD INDEX (c1);
+ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
 LOCK TABLE m1 WRITE, t1 WRITE;
 ALTER TABLE t1 ADD INDEX (c1);
 UNLOCK TABLES;
@@ -3661,4 +3662,16 @@ REPAIR TABLE t2 USE_FRM;
 Table	Op	Msg_type	Msg_text
 test.t2	repair	note	The storage engine for the table doesn't support repair
 DROP TABLE t1, t2;
+#
+# Bug#57002 Assert in upgrade_shared_lock_to_exclusive()
+#           for ALTER TABLE + MERGE tables
+#
+DROP TABLE IF EXISTS t1, m1;
+CREATE TABLE t1(a INT) engine=myisam;
+CREATE TABLE m1(a INT) engine=merge UNION(t1);
+LOCK TABLES t1 READ, m1 WRITE;
+ALTER TABLE t1 engine=myisam;
+ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
+UNLOCK TABLES;
+DROP TABLE m1, t1;
 End of 6.0 tests

=== modified file 'mysql-test/t/merge.test'
--- a/mysql-test/t/merge.test	2010-09-30 10:43:43 +0000
+++ b/mysql-test/t/merge.test	2010-10-05 10:25:30 +0000
@@ -2600,11 +2600,12 @@ UNLOCK TABLES;
 DROP TABLE m1, t1;
 
 --echo #
---echo # Locking the merge table will implicitly lock children.
+--echo # Locking the merge table won't implicitly lock children.
 --echo #
 CREATE TABLE t1 (c1 INT);
 CREATE TABLE m1 (c1 INT) ENGINE=MRG_MyISAM UNION=(t1);
 LOCK TABLE m1 WRITE;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
 ALTER TABLE t1 ADD INDEX (c1);
 LOCK TABLE m1 WRITE, t1 WRITE;
 ALTER TABLE t1 ADD INDEX (c1);
@@ -2776,6 +2777,27 @@ REPAIR TABLE t2 USE_FRM;
 DROP TABLE t1, t2;
 
 
+--echo #
+--echo # Bug#57002 Assert in upgrade_shared_lock_to_exclusive()
+--echo #           for ALTER TABLE + MERGE tables
+--echo #
+
+--disable_warnings
+DROP TABLE IF EXISTS t1, m1;
+--enable_warnings
+
+CREATE TABLE t1(a INT) engine=myisam;
+CREATE TABLE m1(a INT) engine=merge UNION(t1);
+LOCK TABLES t1 READ, m1 WRITE;
+
+# This caused an assert
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+ALTER TABLE t1 engine=myisam;
+
+UNLOCK TABLES;
+DROP TABLE m1, t1;
+
+
 --echo End of 6.0 tests
 
 --disable_result_log

=== modified file 'storage/myisammrg/ha_myisammrg.cc'
--- a/storage/myisammrg/ha_myisammrg.cc	2010-09-08 08:25:37 +0000
+++ b/storage/myisammrg/ha_myisammrg.cc	2010-10-05 10:25:30 +0000
@@ -478,8 +478,9 @@ int ha_myisammrg::add_children_list(void
     /* Set the expected table version, to not cause spurious re-prepare. */
     child_l->set_table_ref_id(mrg_child_def->get_child_table_ref_type(),
                               mrg_child_def->get_child_def_version());
-    /* Use the same metadata lock type for children. */
-    child_l->mdl_request.set_type(parent_l->mdl_request.type);
+    if (! thd->locked_tables_mode &&
+        parent_l->mdl_request.type == MDL_SHARED_NO_WRITE)
+      child_l->mdl_request.set_type(MDL_SHARED_NO_WRITE);
     /* Link TABLE_LIST object into the children list. */
     if (this->children_last_l)
       child_l->prev_global= this->children_last_l;


--===============3323249975450233567==
MIME-Version: 1.0
Content-Type: text/bzr-bundle; charset="us-ascii";
	name="bzr/jon.hauglid@stripped"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

# Bazaar merge directive format 2 (Bazaar 0.90)
# revision_id: jon.hauglid@stripped
# target_branch: file:///export/home/x/mysql-5.5-runtime-bug57002/
# testament_sha1: b5eb45b29a6904b0ecb8ffaa8d34eed4447ef84c
# timestamp: 2010-10-05 12:25:33 +0200
# source_branch: file:///export/home/x/mysql-5.5-bugfixing/
# base_revision_id: jon.hauglid@stripped\
#   mp6vfiu3rl9moqz6
# 
# Begin bundle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--===============3323249975450233567==--