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Bug #11764779 (former 57649)

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FLUSH TABLES under FLUSH TABLES <list> WITH READ LOCK leads 
to assert failure.

This assert was triggered if a statement tried up upgrade a metadata
lock with an active FLUSH TABLE <list> WITH READ LOCK. The assert 
checks that the connection already holds a global intention exclusive
metadata lock. However, FLUSH TABLE <list> WITH READ LOCK does not
acquire this lock in order to be compatible with FLUSH TABLES WITH
READ LOCK. Therefore any metadata lock upgrade caused the assert to
be triggered.

This patch fixes the problem by preventing metadata lock upgrade
if the connection has an active FLUSH TABLE <list> WITH READ LOCK.
ER_TABLE_NOT_LOCKED_FOR_WRITE will instead be reported to the client.

Test case added to flush.test.
This commit is contained in:
Jon Olav Hauglid
2011-03-07 10:08:10 +01:00
parent b326b9a3a0
commit bafe24035d
8 changed files with 95 additions and 30 deletions
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51
sql/sql_base.cc
View File

@@ -1026,7 +1026,7 @@ bool close_cached_tables(THD *thd, TABLE_LIST *tables,
table_list= table_list->next_global)
{
/* A check that the table was locked for write is done by the caller. */
TABLE *table= find_table_for_mdl_upgrade(thd->open_tables, table_list->db,
TABLE *table= find_table_for_mdl_upgrade(thd, table_list->db,
table_list->table_name, TRUE);
/* May return NULL if this table has already been closed via an alias. */
@@ -3120,22 +3120,26 @@ TABLE *find_locked_table(TABLE *list, const char *db, const char *table_name)
lock from the list of open tables, emit error if no such table
found.
@param list List of TABLE objects to be searched
@param thd Thread context
@param db Database name.
@param table_name Name of table.
@param no_error Don't emit error if no suitable TABLE
instance were found.
@note This function checks if the connection holds a global IX
metadata lock. If no such lock is found, it is not safe to
upgrade the lock and ER_TABLE_NOT_LOCKED_FOR_WRITE will be
reported.
@return Pointer to TABLE instance with MDL_SHARED_NO_WRITE,
MDL_SHARED_NO_READ_WRITE, or MDL_EXCLUSIVE metadata
lock, NULL otherwise.
*/
TABLE *find_table_for_mdl_upgrade(TABLE *list, const char *db,
const char *table_name,
bool no_error)
TABLE *find_table_for_mdl_upgrade(THD *thd, const char *db,
const char *table_name, bool no_error)
{
TABLE *tab= find_locked_table(list, db, table_name);
TABLE *tab= find_locked_table(thd->open_tables, db, table_name);
if (!tab)
{
@@ -3143,19 +3147,29 @@ TABLE *find_table_for_mdl_upgrade(TABLE *list, const char *db,
my_error(ER_TABLE_NOT_LOCKED, MYF(0), table_name);
return NULL;
}
else
/*
It is not safe to upgrade the metadata lock without a global IX lock.
This can happen with FLUSH TABLES <list> WITH READ LOCK as we in these
cases don't take a global IX lock in order to be compatible with
global read lock.
*/
if (!thd->mdl_context.is_lock_owner(MDL_key::GLOBAL, "", "",
MDL_INTENTION_EXCLUSIVE))
{
while (tab->mdl_ticket != NULL &&
!tab->mdl_ticket->is_upgradable_or_exclusive() &&
(tab= find_locked_table(tab->next, db, table_name)))
continue;
if (!tab)
{
if (!no_error)
my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0), table_name);
return 0;
}
if (!no_error)
my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0), table_name);
return NULL;
}
while (tab->mdl_ticket != NULL &&
!tab->mdl_ticket->is_upgradable_or_exclusive() &&
(tab= find_locked_table(tab->next, db, table_name)))
continue;
if (!tab && !no_error)
my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0), table_name);
return tab;
}
@@ -4653,8 +4667,7 @@ open_tables_check_upgradable_mdl(THD *thd, TABLE_LIST *tables_start,
Note that find_table_for_mdl_upgrade() will report an error if
no suitable ticket is found.
*/
if (!find_table_for_mdl_upgrade(thd->open_tables, table->db,
table->table_name, FALSE))
if (!find_table_for_mdl_upgrade(thd, table->db, table->table_name, false))
return TRUE;
}
}