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Bug#50561: ALTER PARTITIONS does not have adequate lock, breaks with

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concurrent I_S query

There were two problem:
1) MYSQL_LOCK_IGNORE_FLUSH also ignored name locks
2) there was a race between abort_and_upgrade_locks and
   alter_close_tables
   (i.e. remove_table_from_cache and
    close_data_files_and_morph_locks)

Which allowed the table to be opened with MYSQL_LOCK_IGNORE_FLUSH flag
resulting in renaming a partition that was already in use,
which could cause the table to be unusable.

Solution was to not allow IGNORE_FLUSH to skip waiting for
a named locked table.

And to not release the LOCK_open mutex between the
calls to remove_table_from_cache and
close_data_files_and_morph_locks by merging the functions
abort_and_upgrade_locks and alter_close_tables.
This commit is contained in:
Mattias Jonsson
2010-03-17 15:10:41 +01:00
parent 8d514f2145
commit 3b897f2bc5
9 changed files with 140 additions and 47 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
sql/sql_base.cc
View File

@ -1244,6 +1244,7 @@ void close_thread_tables(THD *thd)
table->s->table_name.str, (long) table));
#endif
DEBUG_SYNC(thd, "before_close_thread_tables");
/*
We are assuming here that thd->derived_tables contains ONLY derived
tables for this substatement. i.e. instead of approach which uses
@ -2502,7 +2503,7 @@ bool check_if_table_exists(THD *thd, TABLE_LIST *table, bool *exists)
put in the thread-open-list.
flags Bitmap of flags to modify how open works:
MYSQL_LOCK_IGNORE_FLUSH - Open table even if
someone has done a flush or namelock on it.
someone has done a flush on it.
No version number checking is done.
MYSQL_OPEN_TEMPORARY_ONLY - Open only temporary
table not the base table or view.
@ -2792,8 +2793,10 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
("Found table '%s.%s' with different refresh version",
table_list->db, table_list->table_name));
if (flags & MYSQL_LOCK_IGNORE_FLUSH)
/* Ignore FLUSH, but not name locks! */
if (flags & MYSQL_LOCK_IGNORE_FLUSH && !table->open_placeholder)
{
DBUG_ASSERT(table->db_stat);
/* Force close at once after usage */
thd->version= table->s->version;
continue;
@ -4448,7 +4451,7 @@ thr_lock_type read_lock_type_for_table(THD *thd, TABLE *table)
counter - number of opened tables will be return using this parameter
flags - bitmap of flags to modify how the tables will be open:
MYSQL_LOCK_IGNORE_FLUSH - open table even if someone has
done a flush or namelock on it.
done a flush on it.
NOTE
Unless we are already in prelocked mode, this function will also precache
@ -5047,7 +5050,7 @@ int open_and_lock_tables_derived(THD *thd, TABLE_LIST *tables, bool derived)
tables - list of tables for open
flags - bitmap of flags to modify how the tables will be open:
MYSQL_LOCK_IGNORE_FLUSH - open table even if someone has
done a flush or namelock on it.
done a flush on it.
RETURN
FALSE - ok
@ -8708,7 +8711,7 @@ bool is_equal(const LEX_STRING *a, const LEX_STRING *b)
/*
SYNOPSIS
abort_and_upgrade_lock()
abort_and_upgrade_lock_and_close_table()
lpt Parameter passing struct
All parameters passed through the ALTER_PARTITION_PARAM_TYPE object
RETURN VALUE
@ -8717,7 +8720,7 @@ bool is_equal(const LEX_STRING *a, const LEX_STRING *b)
Remember old lock level (for possible downgrade later on), abort all
waiting threads and ensure that all keeping locks currently are
completed such that we own the lock exclusively and no other interaction
is ongoing.
is ongoing. Close the table and hold the name lock.
thd Thread object
table Table object
@ -8726,17 +8729,26 @@ bool is_equal(const LEX_STRING *a, const LEX_STRING *b)
old_lock_level Old lock level
*/
int abort_and_upgrade_lock(ALTER_PARTITION_PARAM_TYPE *lpt)
int abort_and_upgrade_lock_and_close_table(ALTER_PARTITION_PARAM_TYPE *lpt)
{
uint flags= RTFC_WAIT_OTHER_THREAD_FLAG | RTFC_CHECK_KILLED_FLAG;
DBUG_ENTER("abort_and_upgrade_locks");
const char *db= lpt->db;
const char *table_name= lpt->table_name;
THD *thd= lpt->thd;
DBUG_ENTER("abort_and_upgrade_lock_and_close_table");
lpt->old_lock_type= lpt->table->reginfo.lock_type;
safe_mutex_assert_not_owner(&LOCK_open);
VOID(pthread_mutex_lock(&LOCK_open));
/* If MERGE child, forward lock handling to parent. */
mysql_lock_abort(lpt->thd, lpt->table->parent ? lpt->table->parent :
lpt->table, TRUE);
VOID(remove_table_from_cache(lpt->thd, lpt->db, lpt->table_name, flags));
mysql_lock_abort(thd, lpt->table->parent ? lpt->table->parent : lpt->table,
TRUE);
if (remove_table_from_cache(thd, db, table_name, flags))
{
VOID(pthread_mutex_unlock(&LOCK_open));
DBUG_RETURN(1);
}
close_data_files_and_morph_locks(thd, db, table_name);
VOID(pthread_mutex_unlock(&LOCK_open));
DBUG_RETURN(0);
}