Bug#56172: Server crashes in ha_partition::reset on

           REBUILD PARTITION under LOCK TABLE

Collapsed patch including updates from the reviews.

In case of failure in ALTER ... PARTITION under LOCK TABLE
the server could crash, due to it had modified the locked
table object, which was not reverted in case of failure,
resulting in a bad table definition used after the failed
command.

Solved by instead of altering the locked table object and
its partition_info struct, creating an internal temporary
intermediate table object used for altering,
just like the non partitioned mysql_alter_table.
So if an error occur before the alter operation is complete,
the original table is not modified at all.
But if the alter operation have succeeded so far that it
must be completed as whole,
the table is properly closed and reopened.
(The completion on failure is done by the ddl_log.)

mysql-test/suite/parts/inc/partition_fail.inc

@@ -16,3 +16,23 @@ SHOW CREATE TABLE t1;
 --sorted_result
 SELECT * FROM t1;
 DROP TABLE t1;
+
+--echo # Same test under LOCK TABLE
+--eval $create_statement
+--eval $insert_statement
+--echo # State before failure
+--list_files $DATADIR/test
+SHOW CREATE TABLE t1;
+--sorted_result
+SELECT * FROM t1;
+LOCK TABLE t1 WRITE;
+--disable_abort_on_error
+--eval $fail_statement
+--enable_abort_on_error
+--echo # State after failure
+--list_files $DATADIR/test
+SHOW CREATE TABLE t1;
+--sorted_result
+SELECT * FROM t1;
+UNLOCK TABLES;
+DROP TABLE t1;

mysql-test/suite/parts/r/partition_special_innodb.result

@@ -238,11 +238,10 @@ LOCK TABLE t1 READ;
 # Third attempt: says that the table does not exist
 ALTER TABLE t1 ADD PARTITION PARTITIONS 2;
 ERROR HY000: Lock wait timeout exceeded; try restarting transaction
-# Check table returns the same
+# Check table returns the same (not after fixing bug#56172!)
 CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text
-test.t1	check	Error	Lock wait timeout exceeded; try restarting transaction
-test.t1	check	error	Corrupt
+test.t1	check	status	OK
 UNLOCK TABLES;
 DROP TABLE t1;
 CREATE TABLE t2 ( i INT NOT NULL AUTO_INCREMENT PRIMARY KEY, f INT )

mysql-test/suite/parts/t/partition_special_innodb.test

@@ -111,7 +111,7 @@ LOCK TABLE t1 READ;
 --echo # Third attempt: says that the table does not exist
 --error ER_LOCK_WAIT_TIMEOUT
 ALTER TABLE t1 ADD PARTITION PARTITIONS 2;
---echo # Check table returns the same
+--echo # Check table returns the same (not after fixing bug#56172!)
 CHECK TABLE t1;
 
 --connection con1

sql/sql_partition.h

@@ -54,6 +54,7 @@ typedef struct st_lock_param_type
   HA_CREATE_INFO *create_info;
   Alter_info *alter_info;
   TABLE *table;
+  TABLE *old_table;
   KEY *key_info_buffer;
   const char *db;
   const char *table_name;
@@ -252,14 +253,17 @@ uint fast_alter_partition_table(THD *thd, TABLE *table,
                                 TABLE_LIST *table_list,
                                 char *db,
                                 const char *table_name,
-                                uint fast_alter_partition);
+                                TABLE  *fast_alter_table);
 uint set_part_state(Alter_info *alter_info, partition_info *tab_part_info,
                     enum partition_state part_state);
 uint prep_alter_part_table(THD *thd, TABLE *table, Alter_info *alter_info,
                            HA_CREATE_INFO *create_info,
                            handlerton *old_db_type,
                            bool *partition_changed,
-                           uint *fast_alter_partition);
+                           char *db,
+                           const char *table_name,
+                           const char *path,
+                           TABLE **fast_alter_table);
 char *generate_partition_syntax(partition_info *part_info,
                                 uint *buf_length, bool use_sql_alloc,
                                 bool show_partition_options,

sql/sql_table.cc

@@ -1725,8 +1725,6 @@ bool mysql_write_frm(ALTER_PARTITION_PARAM_TYPE *lpt, uint flags)
                                                   CHF_DELETE_FLAG, NULL) ||
         deactivate_ddl_log_entry(part_info->frm_log_entry->entry_pos) ||
         (sync_ddl_log(), FALSE) ||
-#endif
-#ifdef WITH_PARTITION_STORAGE_ENGINE
         mysql_file_rename(key_file_frm,
                           shadow_frm_name, frm_name, MYF(MY_WME)) ||
         lpt->table->file->ha_create_handler_files(path, shadow_path,
@@ -5599,7 +5597,7 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
   handlerton *old_db_type, *new_db_type, *save_old_db_type;
   enum_alter_table_change_level need_copy_table= ALTER_TABLE_METADATA_ONLY;
 #ifdef WITH_PARTITION_STORAGE_ENGINE
-  uint fast_alter_partition= 0;
+  TABLE *table_for_fast_alter_partition= NULL;
   bool partition_changed= FALSE;
 #endif
   bool need_lock_for_indexes= TRUE;
@@ -5968,7 +5966,9 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
 
 #ifdef WITH_PARTITION_STORAGE_ENGINE
   if (prep_alter_part_table(thd, table, alter_info, create_info, old_db_type,
-                            &partition_changed, &fast_alter_partition))
+                            &partition_changed,
+                            db, table_name, path,
+                            &table_for_fast_alter_partition))
     goto err;
 #endif
   /*
@@ -6201,12 +6201,12 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
     create_info->frm_only= 1;
 
 #ifdef WITH_PARTITION_STORAGE_ENGINE
-  if (fast_alter_partition)
+  if (table_for_fast_alter_partition)
   {
     DBUG_RETURN(fast_alter_partition_table(thd, table, alter_info,
                                            create_info, table_list,
                                            db, table_name,
-                                           fast_alter_partition));
+                                           table_for_fast_alter_partition));
   }
 #endif
 
@@ -6686,6 +6686,11 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
                           create_info->frm_only ? FN_IS_TMP | FRM_ONLY : FN_IS_TMP);
 
 err:
+#ifdef WITH_PARTITION_STORAGE_ENGINE
+  /* If prep_alter_part_table created an intermediate table, destroy it. */
+  if (table_for_fast_alter_partition)
+    close_temporary(table_for_fast_alter_partition, 1, 0);
+#endif /* WITH_PARTITION_STORAGE_ENGINE */
   /*
     No default value was provided for a DATE/DATETIME field, the
     current sql_mode doesn't allow the '0000-00-00' value and