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mariadb/storage/innodb_plugin/include/mtr0mtr.h
Marko Mäkelä ae309bd336 Bug#13721257 RACE CONDITION IN UPDATES OR INSERTS OF WIDE RECORDS 
This bug was originally filed and fixed as Bug#12612184. The original
fix was buggy, and it was patched by Bug#12704861. Also that patch was
buggy (potentially breaking crash recovery), and both fixes were
reverted.

This fix was not ported to the built-in InnoDB of MySQL 5.1, because
the function signatures of many core functions are different from
InnoDB Plugin and later versions. The block allocation routines and
their callers would have to changed so that they handle block
descriptors instead of page frames.

When a record is updated so that its size grows, non-updated columns
can be selected for external (off-page) storage. The bug is that the
initially inserted updated record contains an all-zero BLOB pointer to
the field that was not updated. Only after the BLOB pages have been
allocated and written, the valid pointer can be written to the record.

Between the release of the page latch in mtr_commit(mtr) after
btr_cur_pessimistic_update() and the re-latching of the page in
btr_pcur_restore_position(), other threads can see the invalid BLOB
pointer consisting of 20 zero bytes. Moreover, if the system crashes
at this point, the situation could persist after crash recovery, and
the contents of the non-updated column would be permanently lost.

The problem is amplified by the ROW_FORMAT=DYNAMIC and
ROW_FORMAT=COMPRESSED that were introduced in
innodb_file_format=barracuda in InnoDB Plugin, but the bug does exist
in all InnoDB versions.

The fix is as follows. After a pessimistic B-tree operation that needs
to write out off-page columns, allocate the pages for these columns in
the mini-transaction that performed the B-tree operation (btr_mtr),
but write the pages in a separate mini-transaction (blob_mtr). Do
mtr_commit(blob_mtr) before mtr_commit(btr_mtr). A quirk: Do not reuse
pages that were previously freed in btr_mtr. Only write the off-page
columns to 'fresh' pages.

In this way, crash recovery will see redo log entries for blob_mtr
before any redo log entry for btr_mtr. It will apply the BLOB page
writes to pages that were marked free at that point. If crash recovery
fails to see all of the btr_mtr redo log, there will be some
unreachable BLOB data in free pages, but the B-tree will be in a
consistent state.

btr_page_alloc_low(): Renamed from btr_page_alloc(). Add the parameter
init_mtr. Return an allocated block, or NULL. If init_mtr!=mtr but
the page was already X-latched in mtr, do not initialize the page.

btr_page_alloc(): Wrapper for btr_page_alloc_for_ibuf() and
btr_page_alloc_low().

btr_page_free(): Add a debug assertion that the page was a B-tree page.

btr_lift_page_up(): Return the father block.

btr_compress(), btr_cur_compress_if_useful(): Add the parameter ibool
adjust, for adjusting the cursor position.

btr_cur_pessimistic_update(): Preserve the cursor position when
big_rec will be written and the new flag BTR_KEEP_POS_FLAG is defined.
Remove a duplicate rec_get_offsets() call. Keep the X-latch on
index->lock when big_rec is needed.

btr_store_big_rec_extern_fields(): Replace update_inplace with
an operation code, and local_mtr with btr_mtr. When not doing a
fresh insert and btr_mtr has freed pages, put aside any pages that
were previously X-latched in btr_mtr, and free the pages after
writing out all data. The data must be written to 'fresh' pages,
because btr_mtr will be committed and written to the redo log after
the BLOB writes have been written to the redo log.

btr_blob_op_is_update(): Check if an operation passed to
btr_store_big_rec_extern_fields() is an update or insert-by-update.

fseg_alloc_free_page_low(), fsp_alloc_free_page(),
fseg_alloc_free_extent(), fseg_alloc_free_page_general(): Add the
parameter init_mtr. Return an allocated block, or NULL. If
init_mtr!=mtr but the page was already X-latched in mtr, do not
initialize the page.

xdes_get_descriptor_with_space_hdr(): Assert that the file space
header is being X-latched.

fsp_alloc_from_free_frag(): Refactored from fsp_alloc_free_page().

fsp_page_create(): New function, for allocating, X-latching and
potentially initializing a page. If init_mtr!=mtr but the page was
already X-latched in mtr, do not initialize the page.

fsp_free_page(): Add ut_ad(0) to the error outcomes.

fsp_free_page(), fseg_free_page_low(): Increment mtr->n_freed_pages.

fsp_alloc_seg_inode_page(), fseg_create_general(): Assert that the
page was not previously X-latched in the mini-transaction. A file
segment or inode page should never be allocated in the middle of an
mini-transaction that frees pages, such as btr_cur_pessimistic_delete().

fseg_alloc_free_page_low(): If the hinted page was allocated, skip the
check if the tablespace should be extended. Return NULL instead of
FIL_NULL on failure. Remove the flag frag_page_allocated. Instead,
return directly, because the page would already have been initialized.

fseg_find_free_frag_page_slot() would return ULINT_UNDEFINED on error,
not FIL_NULL. Correct a bogus assertion.

fseg_alloc_free_page(): Redefine as a wrapper macro around
fseg_alloc_free_page_general().

buf_block_buf_fix_inc(): Move the definition from the buf0buf.ic to
buf0buf.h, so that it can be called from other modules.

mtr_t: Add n_freed_pages (number of pages that have been freed).

page_rec_get_nth_const(), page_rec_get_nth(): The inverse function of
page_rec_get_n_recs_before(), get the nth record of the record
list. This is faster than iterating the linked list. Refactored from
page_get_middle_rec().

trx_undo_rec_copy(): Add a debug assertion for the length.

trx_undo_add_page(): Return a block descriptor or NULL instead of a
page number or FIL_NULL.

trx_undo_report_row_operation(): Add debug assertions.

trx_sys_create_doublewrite_buf(): Assert that each page was not
previously X-latched.

page_cur_insert_rec_zip_reorg(): Make use of page_rec_get_nth().

row_ins_clust_index_entry_by_modify(): Pass BTR_KEEP_POS_FLAG, so that
the repositioning of the cursor can be avoided.

row_ins_index_entry_low(): Add DEBUG_SYNC points before and after
writing off-page columns. If inserting by updating a delete-marked
record, do not reposition the cursor or commit the mini-transaction
before writing the off-page columns.

row_build(): Tighten a debug assertion about null BLOB pointers.

row_upd_clust_rec(): Add DEBUG_SYNC points before and after writing
off-page columns. Do not reposition the cursor or commit the
mini-transaction before writing the off-page columns.

rb:939 approved by Jimmy Yang
2012-02-17 11:42:04 +02:00

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/*****************************************************************************
Copyright (c) 1995, 2012, Oracle and/or its affiliates. All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file include/mtr0mtr.h
Mini-transaction buffer
Created 11/26/1995 Heikki Tuuri
*******************************************************/
#ifndef mtr0mtr_h
#define mtr0mtr_h
#include "univ.i"
#include "mem0mem.h"
#include "dyn0dyn.h"
#include "buf0types.h"
#include "sync0rw.h"
#include "ut0byte.h"
#include "mtr0types.h"
#include "page0types.h"
/* Logging modes for a mini-transaction */
#define MTR_LOG_ALL 21 /* default mode: log all operations
modifying disk-based data */
#define MTR_LOG_NONE 22 /* log no operations */
/*#define MTR_LOG_SPACE 23 */ /* log only operations modifying
file space page allocation data
(operations in fsp0fsp.* ) */
#define MTR_LOG_SHORT_INSERTS 24 /* inserts are logged in a shorter
form */
/* Types for the mlock objects to store in the mtr memo; NOTE that the
first 3 values must be RW_S_LATCH, RW_X_LATCH, RW_NO_LATCH */
#define MTR_MEMO_PAGE_S_FIX RW_S_LATCH
#define MTR_MEMO_PAGE_X_FIX RW_X_LATCH
#define MTR_MEMO_BUF_FIX RW_NO_LATCH
#ifdef UNIV_DEBUG
# define MTR_MEMO_MODIFY 54
#endif /* UNIV_DEBUG */
#define MTR_MEMO_S_LOCK 55
#define MTR_MEMO_X_LOCK 56
/** @name Log item types
The log items are declared 'byte' so that the compiler can warn if val
and type parameters are switched in a call to mlog_write_ulint. NOTE!
For 1 - 8 bytes, the flag value must give the length also! @{ */
#define MLOG_SINGLE_REC_FLAG 128 /*!< if the mtr contains only
one log record for one page,
i.e., write_initial_log_record
has been called only once,
this flag is ORed to the type
of that first log record */
#define MLOG_1BYTE (1) /*!< one byte is written */
#define MLOG_2BYTES (2) /*!< 2 bytes ... */
#define MLOG_4BYTES (4) /*!< 4 bytes ... */
#define MLOG_8BYTES (8) /*!< 8 bytes ... */
#define MLOG_REC_INSERT ((byte)9) /*!< record insert */
#define MLOG_REC_CLUST_DELETE_MARK ((byte)10) /*!< mark clustered index record
deleted */
#define MLOG_REC_SEC_DELETE_MARK ((byte)11) /*!< mark secondary index record
deleted */
#define MLOG_REC_UPDATE_IN_PLACE ((byte)13) /*!< update of a record,
preserves record field sizes */
#define MLOG_REC_DELETE ((byte)14) /*!< delete a record from a
page */
#define MLOG_LIST_END_DELETE ((byte)15) /*!< delete record list end on
index page */
#define MLOG_LIST_START_DELETE ((byte)16) /*!< delete record list start on
index page */
#define MLOG_LIST_END_COPY_CREATED ((byte)17) /*!< copy record list end to a
new created index page */
#define MLOG_PAGE_REORGANIZE ((byte)18) /*!< reorganize an
index page in
ROW_FORMAT=REDUNDANT */
#define MLOG_PAGE_CREATE ((byte)19) /*!< create an index page */
#define MLOG_UNDO_INSERT ((byte)20) /*!< insert entry in an undo
log */
#define MLOG_UNDO_ERASE_END ((byte)21) /*!< erase an undo log
page end */
#define MLOG_UNDO_INIT ((byte)22) /*!< initialize a page in an
undo log */
#define MLOG_UNDO_HDR_DISCARD ((byte)23) /*!< discard an update undo log
header */
#define MLOG_UNDO_HDR_REUSE ((byte)24) /*!< reuse an insert undo log
header */
#define MLOG_UNDO_HDR_CREATE ((byte)25) /*!< create an undo
log header */
#define MLOG_REC_MIN_MARK ((byte)26) /*!< mark an index
record as the
predefined minimum
record */
#define MLOG_IBUF_BITMAP_INIT ((byte)27) /*!< initialize an
ibuf bitmap page */
/*#define MLOG_FULL_PAGE ((byte)28) full contents of a page */
#ifdef UNIV_LOG_LSN_DEBUG
# define MLOG_LSN ((byte)28) /* current LSN */
#endif
#define MLOG_INIT_FILE_PAGE ((byte)29) /*!< this means that a
file page is taken
into use and the prior
contents of the page
should be ignored: in
recovery we must not
trust the lsn values
stored to the file
page */
#define MLOG_WRITE_STRING ((byte)30) /*!< write a string to
a page */
#define MLOG_MULTI_REC_END ((byte)31) /*!< if a single mtr writes
several log records,
this log record ends the
sequence of these records */
#define MLOG_DUMMY_RECORD ((byte)32) /*!< dummy log record used to
pad a log block full */
#define MLOG_FILE_CREATE ((byte)33) /*!< log record about an .ibd
file creation */
#define MLOG_FILE_RENAME ((byte)34) /*!< log record about an .ibd
file rename */
#define MLOG_FILE_DELETE ((byte)35) /*!< log record about an .ibd
file deletion */
#define MLOG_COMP_REC_MIN_MARK ((byte)36) /*!< mark a compact
index record as the
predefined minimum
record */
#define MLOG_COMP_PAGE_CREATE ((byte)37) /*!< create a compact
index page */
#define MLOG_COMP_REC_INSERT ((byte)38) /*!< compact record insert */
#define MLOG_COMP_REC_CLUST_DELETE_MARK ((byte)39)
/*!< mark compact
clustered index record
deleted */
#define MLOG_COMP_REC_SEC_DELETE_MARK ((byte)40)/*!< mark compact
secondary index record
deleted; this log
record type is
redundant, as
MLOG_REC_SEC_DELETE_MARK
is independent of the
record format. */
#define MLOG_COMP_REC_UPDATE_IN_PLACE ((byte)41)/*!< update of a
compact record,
preserves record field
sizes */
#define MLOG_COMP_REC_DELETE ((byte)42) /*!< delete a compact record
from a page */
#define MLOG_COMP_LIST_END_DELETE ((byte)43) /*!< delete compact record list
end on index page */
#define MLOG_COMP_LIST_START_DELETE ((byte)44) /*!< delete compact record list
start on index page */
#define MLOG_COMP_LIST_END_COPY_CREATED ((byte)45)
/*!< copy compact
record list end to a
new created index
page */
#define MLOG_COMP_PAGE_REORGANIZE ((byte)46) /*!< reorganize an index page */
#define MLOG_FILE_CREATE2 ((byte)47) /*!< log record about creating
an .ibd file, with format */
#define MLOG_ZIP_WRITE_NODE_PTR ((byte)48) /*!< write the node pointer of
a record on a compressed
non-leaf B-tree page */
#define MLOG_ZIP_WRITE_BLOB_PTR ((byte)49) /*!< write the BLOB pointer
of an externally stored column
on a compressed page */
#define MLOG_ZIP_WRITE_HEADER ((byte)50) /*!< write to compressed page
header */
#define MLOG_ZIP_PAGE_COMPRESS ((byte)51) /*!< compress an index page */
#define MLOG_BIGGEST_TYPE ((byte)51) /*!< biggest value (used in
assertions) */
/* @} */
/** @name Flags for MLOG_FILE operations
(stored in the page number parameter, called log_flags in the
functions). The page number parameter was originally written as 0. @{ */
#define MLOG_FILE_FLAG_TEMP 1 /*!< identifies TEMPORARY TABLE in
MLOG_FILE_CREATE, MLOG_FILE_CREATE2 */
/* @} */
/***************************************************************//**
Starts a mini-transaction and creates a mini-transaction handle
and buffer in the memory buffer given by the caller.
@return mtr buffer which also acts as the mtr handle */
UNIV_INLINE
mtr_t*
mtr_start(
/*======*/
mtr_t* mtr); /*!< in: memory buffer for the mtr buffer */
/***************************************************************//**
Commits a mini-transaction. */
UNIV_INTERN
void
mtr_commit(
/*=======*/
mtr_t* mtr); /*!< in: mini-transaction */
/**********************************************************//**
Sets and returns a savepoint in mtr.
@return savepoint */
UNIV_INLINE
ulint
mtr_set_savepoint(
/*==============*/
mtr_t* mtr); /*!< in: mtr */
#ifndef UNIV_HOTBACKUP
/**********************************************************//**
Releases the (index tree) s-latch stored in an mtr memo after a
savepoint. */
UNIV_INLINE
void
mtr_release_s_latch_at_savepoint(
/*=============================*/
mtr_t* mtr, /*!< in: mtr */
ulint savepoint, /*!< in: savepoint */
rw_lock_t* lock); /*!< in: latch to release */
#else /* !UNIV_HOTBACKUP */
# define mtr_release_s_latch_at_savepoint(mtr,savepoint,lock) ((void) 0)
#endif /* !UNIV_HOTBACKUP */
/***************************************************************//**
Gets the logging mode of a mini-transaction.
@return logging mode: MTR_LOG_NONE, ... */
UNIV_INLINE
ulint
mtr_get_log_mode(
/*=============*/
mtr_t* mtr); /*!< in: mtr */
/***************************************************************//**
Changes the logging mode of a mini-transaction.
@return old mode */
UNIV_INLINE
ulint
mtr_set_log_mode(
/*=============*/
mtr_t* mtr, /*!< in: mtr */
ulint mode); /*!< in: logging mode: MTR_LOG_NONE, ... */
/********************************************************//**
Reads 1 - 4 bytes from a file page buffered in the buffer pool.
@return value read */
UNIV_INTERN
ulint
mtr_read_ulint(
/*===========*/
const byte* ptr, /*!< in: pointer from where to read */
ulint type, /*!< in: MLOG_1BYTE, MLOG_2BYTES, MLOG_4BYTES */
mtr_t* mtr); /*!< in: mini-transaction handle */
/********************************************************//**
Reads 8 bytes from a file page buffered in the buffer pool.
@return value read */
UNIV_INTERN
dulint
mtr_read_dulint(
/*============*/
const byte* ptr, /*!< in: pointer from where to read */
mtr_t* mtr); /*!< in: mini-transaction handle */
#ifndef UNIV_HOTBACKUP
/*********************************************************************//**
This macro locks an rw-lock in s-mode. */
#define mtr_s_lock(B, MTR) mtr_s_lock_func((B), __FILE__, __LINE__,\
(MTR))
/*********************************************************************//**
This macro locks an rw-lock in x-mode. */
#define mtr_x_lock(B, MTR) mtr_x_lock_func((B), __FILE__, __LINE__,\
(MTR))
/*********************************************************************//**
NOTE! Use the macro above!
Locks a lock in s-mode. */
UNIV_INLINE
void
mtr_s_lock_func(
/*============*/
rw_lock_t* lock, /*!< in: rw-lock */
const char* file, /*!< in: file name */
ulint line, /*!< in: line number */
mtr_t* mtr); /*!< in: mtr */
/*********************************************************************//**
NOTE! Use the macro above!
Locks a lock in x-mode. */
UNIV_INLINE
void
mtr_x_lock_func(
/*============*/
rw_lock_t* lock, /*!< in: rw-lock */
const char* file, /*!< in: file name */
ulint line, /*!< in: line number */
mtr_t* mtr); /*!< in: mtr */
#endif /* !UNIV_HOTBACKUP */
/***************************************************//**
Releases an object in the memo stack. */
UNIV_INTERN
void
mtr_memo_release(
/*=============*/
mtr_t* mtr, /*!< in: mtr */
void* object, /*!< in: object */
ulint type); /*!< in: object type: MTR_MEMO_S_LOCK, ... */
#ifdef UNIV_DEBUG
# ifndef UNIV_HOTBACKUP
/**********************************************************//**
Checks if memo contains the given item.
@return TRUE if contains */
UNIV_INLINE
ibool
mtr_memo_contains(
/*==============*/
mtr_t* mtr, /*!< in: mtr */
const void* object, /*!< in: object to search */
ulint type); /*!< in: type of object */
/**********************************************************//**
Checks if memo contains the given page.
@return TRUE if contains */
UNIV_INTERN
ibool
mtr_memo_contains_page(
/*===================*/
mtr_t* mtr, /*!< in: mtr */
const byte* ptr, /*!< in: pointer to buffer frame */
ulint type); /*!< in: type of object */
/*********************************************************//**
Prints info of an mtr handle. */
UNIV_INTERN
void
mtr_print(
/*======*/
mtr_t* mtr); /*!< in: mtr */
# else /* !UNIV_HOTBACKUP */
# define mtr_memo_contains(mtr, object, type) TRUE
# define mtr_memo_contains_page(mtr, ptr, type) TRUE
# endif /* !UNIV_HOTBACKUP */
#endif /* UNIV_DEBUG */
/*######################################################################*/
#define MTR_BUF_MEMO_SIZE 200 /* number of slots in memo */
/***************************************************************//**
Returns the log object of a mini-transaction buffer.
@return log */
UNIV_INLINE
dyn_array_t*
mtr_get_log(
/*========*/
mtr_t* mtr); /*!< in: mini-transaction */
/***************************************************//**
Pushes an object to an mtr memo stack. */
UNIV_INLINE
void
mtr_memo_push(
/*==========*/
mtr_t* mtr, /*!< in: mtr */
void* object, /*!< in: object */
ulint type); /*!< in: object type: MTR_MEMO_S_LOCK, ... */
/* Type definition of a mini-transaction memo stack slot. */
typedef struct mtr_memo_slot_struct mtr_memo_slot_t;
struct mtr_memo_slot_struct{
ulint type; /*!< type of the stored object (MTR_MEMO_S_LOCK, ...) */
void* object; /*!< pointer to the object */
};
/* Mini-transaction handle and buffer */
struct mtr_struct{
#ifdef UNIV_DEBUG
ulint state; /*!< MTR_ACTIVE, MTR_COMMITTING, MTR_COMMITTED */
#endif
dyn_array_t memo; /*!< memo stack for locks etc. */
dyn_array_t log; /*!< mini-transaction log */
ibool modifications;
/*!< TRUE if the mini-transaction
modified buffer pool pages */
ulint n_log_recs;
/* count of how many page initial log records
have been written to the mtr log */
ulint n_freed_pages;
/* number of pages that have been freed in
this mini-transaction */
ulint log_mode; /* specifies which operations should be
logged; default value MTR_LOG_ALL */
ib_uint64_t start_lsn;/* start lsn of the possible log entry for
this mtr */
ib_uint64_t end_lsn;/* end lsn of the possible log entry for
this mtr */
#ifdef UNIV_DEBUG
ulint magic_n;
#endif /* UNIV_DEBUG */
};
#ifdef UNIV_DEBUG
# define MTR_MAGIC_N 54551
#endif /* UNIV_DEBUG */
#define MTR_ACTIVE 12231
#define MTR_COMMITTING 56456
#define MTR_COMMITTED 34676
#ifndef UNIV_NONINL
#include "mtr0mtr.ic"
#endif
#endif
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