Innodb clone descriptors. More...

#include "clone0desc.h"
#include "dict0dict.h"
#include "mach0data.h"

Functions
uint	choose_desc_version (const byte *ref_loc)
	Choose lowest descriptor version between reference locator and currently supported version. More...

bool	clone_validate_locator (const byte *desc_loc, uint desc_len)
	Check if clone locator is valid. More...

bool	DESC_CHECK_FLAG (ulint flag, ulint bit)
	Check a specific bit in flag. More...

void	DESC_SET_FLAG (ulint &flag, ulint bit)
	Set a specific bit in flag. More...

Variables
static const uint	CLONE_DESC_MAX_VERSION = 100
	Maximum supported descriptor version. More...

static const uint	CLONE_DESC_VER_OFFSET = 0
	Header: Version is in first 4 bytes. More...

static const uint	CLONE_DESC_LEN_OFFSET = CLONE_DESC_VER_OFFSET + 4
	Header: Total length is stored in next 4 bytes. More...

static const uint	CLONE_DESC_TYPE_OFFSET = CLONE_DESC_LEN_OFFSET + 4
	Header: Descriptor type is in next 4 bytes. More...

static const uint	CLONE_DESC_HEADER_LEN = CLONE_DESC_TYPE_OFFSET + 4
	Header: Fixed length. More...

static const uint	CLONE_TASK_INDEX_OFFSET = CLONE_DESC_HEADER_LEN
	Task: Clone task index in 4 bytes. More...

static const uint	CLONE_TASK_CHUNK_OFFSET = CLONE_TASK_INDEX_OFFSET + 4
	Task: Task chunk number in 4 bytes. More...

static const uint	CLONE_TASK_BLOCK_OFFSET = CLONE_TASK_CHUNK_OFFSET + 4
	Task: Task block number in 4 bytes. More...

static const uint	CLONE_TASK_META_LEN = CLONE_TASK_BLOCK_OFFSET + 4
	Task: Total length. More...

static const uint	CLONE_LOC_CID_OFFSET = CLONE_DESC_HEADER_LEN
	Locator: Clone identifier in 8 bytes. More...

static const uint	CLONE_LOC_SID_OFFSET = CLONE_LOC_CID_OFFSET + 8
	Locator: Snapshot identifier in 8 bytes. More...

static const uint	CLONE_LOC_IDX_OFFSET = CLONE_LOC_SID_OFFSET + 8
	Locator: Clone array index in 4 bytes. More...

static const uint	CLONE_LOC_STATE_OFFSET = CLONE_LOC_IDX_OFFSET + 4
	Locator: Clone Snapshot state in 1 byte. More...

static const uint	CLONE_LOC_META_OFFSET = CLONE_LOC_STATE_OFFSET + 1
	Locator: Clone Snapshot sub-state in 1 byte. More...

static const uint	CLONE_DESC_LOC_BASE_LEN = CLONE_LOC_META_OFFSET + 1
	Locator: Total length. More...

static const uint	CLONE_FILE_STATE_OFFSET = CLONE_DESC_HEADER_LEN
	File Metadata: Snapshot state in 4 bytes. More...

static const uint	CLONE_FILE_SIZE_OFFSET = CLONE_FILE_STATE_OFFSET + 4
	File Metadata: File size in 8 bytes. More...

static const uint	CLONE_FILE_ALLOC_SIZE_OFFSET = CLONE_FILE_SIZE_OFFSET + 8
	File Metadata: Sparse file allocation size on disk in 8 bytes. More...

static const uint	CLONE_FILE_FSP_OFFSET = CLONE_FILE_ALLOC_SIZE_OFFSET + 8
	File Metadata: FSP flags in 4 bytes. More...

static const uint	CLONE_FILE_FSBLK_OFFSET = CLONE_FILE_FSP_OFFSET + 4
	File Metadata: File system block size for compressed tables in 4 bytes. More...

static const uint	CLONE_FILE_FLAGS_OFFSET = CLONE_FILE_FSBLK_OFFSET + 4
	File Metadata: File space flags in next 2 bytes [Maximum 16 flags]. More...

static const uint	CLONE_DESC_FILE_FLAG_ZLIB = 1
	Clone File Flag: Compression type ZLIB. More...

static const uint	CLONE_DESC_FILE_FLAG_LZ4 = 2
	Clone File Flag: Compression type LZ4. More...

static const uint	CLONE_DESC_FILE_FLAG_AES = 3
	Clone File Flag: Encryption type AES. More...

static const uint	CLONE_DESC_FILE_FLAG_RENAMED = 4
	Clone File Flag: File is renamed. More...

static const uint	CLONE_DESC_FILE_FLAG_DELETED = 5
	Clone File Flag: File is deleted. More...

static const uint	CLONE_DESC_FILE_HAS_KEY = 6
	Clone File Flag: File metadata has encryption key. More...

static const uint	CLONE_FILE_SPACE_ID_OFFSET = CLONE_FILE_FLAGS_OFFSET + 2
	File Metadata: Tablespace ID in 4 bytes. More...

static const uint	CLONE_FILE_IDX_OFFSET = CLONE_FILE_SPACE_ID_OFFSET + 4
	File Metadata: File index in 4 bytes. More...

static const uint	CLONE_FILE_BCHUNK_OFFSET = CLONE_FILE_IDX_OFFSET + 4
	File Metadata: First chunk number in 4 bytes. More...

static const uint	CLONE_FILE_ECHUNK_OFFSET = CLONE_FILE_BCHUNK_OFFSET + 4
	File Metadata: Last chunk number in 4 bytes. More...

static const uint	CLONE_FILE_FNAMEL_OFFSET = CLONE_FILE_ECHUNK_OFFSET + 4
	File Metadata: File name length in 4 bytes. More...

static const uint	CLONE_FILE_FNAME_OFFSET = CLONE_FILE_FNAMEL_OFFSET + 4
	File Metadata: File name. More...

static const uint	CLONE_FILE_BASE_LEN = CLONE_FILE_FNAME_OFFSET
	File Metadata: Length excluding the file name. More...

static const uint	CLONE_DESC_STATE_OFFSET = CLONE_DESC_HEADER_LEN
	Clone State: Snapshot state in 4 bytes. More...

static const uint	CLONE_DESC_TASK_OFFSET = CLONE_DESC_STATE_OFFSET + 4
	Clone State: Task index in 4 bytes. More...

static const uint	CLONE_DESC_STATE_NUM_CHUNKS = CLONE_DESC_TASK_OFFSET + 4
	Clone State: Number of chunks in 4 bytes. More...

static const uint	CLONE_DESC_STATE_NUM_FILES = CLONE_DESC_STATE_NUM_CHUNKS + 4
	Clone State: Number of files in 4 bytes. More...

static const uint	CLONE_DESC_STATE_EST_BYTES = CLONE_DESC_STATE_NUM_FILES + 4
	Clone State: Estimated number of bytes in 8 bytes. More...

static const uint	CLONE_DESC_STATE_EST_DISK = CLONE_DESC_STATE_EST_BYTES + 8
	Clone State: Estimated number of bytes in 8 bytes. More...

static const uint	CLONE_DESC_STATE_FLAGS = CLONE_DESC_STATE_EST_DISK + 8
	Clone State: flags in 2 byte [max 16 flags]. More...

static const uint	CLONE_DESC_STATE_LEN = CLONE_DESC_STATE_FLAGS + 2
	Clone State: Total length. More...

static const uint	CLONE_DESC_STATE_FLAG_START = 1
	Clone State Flag: Start processing state. More...

static const uint	CLONE_DESC_STATE_FLAG_ACK = 2
	Clone State Flag: Acknowledge processing state. More...

static const uint	CLONE_DATA_STATE_OFFSET = CLONE_DESC_HEADER_LEN
	Clone Data: Snapshot state in 4 bytes. More...

static const uint	CLONE_DATA_TASK_INDEX_OFFSET = CLONE_DATA_STATE_OFFSET + 4
	Clone Data: Task index in 4 bytes. More...

static const uint	CLONE_DATA_TASK_CHUNK_OFFSET
	Clone Data: Current chunk number in 4 bytes. More...

static const uint	CLONE_DATA_TASK_BLOCK_OFFSET
	Clone Data: Current block number in 4 bytes. More...

static const uint	CLONE_DATA_FILE_IDX_OFFSET = CLONE_DATA_TASK_BLOCK_OFFSET + 4
	Clone Data: Data file index in 4 bytes. More...

static const uint	CLONE_DATA_LEN_OFFSET = CLONE_DATA_FILE_IDX_OFFSET + 4
	Clone Data: Data length in 4 bytes. More...

static const uint	CLONE_DATA_FOFF_OFFSET = CLONE_DATA_LEN_OFFSET + 4
	Clone Data: Data file offset in 8 bytes. More...

static const uint	CLONE_DATA_FILE_SIZE_OFFSET = CLONE_DATA_FOFF_OFFSET + 8
	Clone Data: Updated file size in 8 bytes. More...

static const uint	CLONE_DESC_DATA_LEN = CLONE_DATA_FILE_SIZE_OFFSET + 8
	Clone Data: Total length. More...

Detailed Description

Innodb clone descriptors.

Function Documentation

◆ choose_desc_version()

uint choose_desc_version ( const byte * ref_loc )

Choose lowest descriptor version between reference locator and currently supported version.

Parameters

[in] ref_loc reference locator

Returns: chosen version

◆ clone_validate_locator()

bool clone_validate_locator	(	const byte *	desc_loc,
		uint	desc_len
	)

Check if clone locator is valid.

Parameters

[in]	desc_loc	serialized descriptor
[in]	desc_len	descriptor length

Returns: true, if valid locator

◆ DESC_CHECK_FLAG()

bool DESC_CHECK_FLAG	(	ulint	flag,
		ulint	bit
	)

inline

Check a specific bit in flag.

Parameters

[in]	flag	bit flag
[in]	bit	check bit

Returns: true, iff bit is set in flag.

◆ DESC_SET_FLAG()

void DESC_SET_FLAG	(	ulint &	flag,
		ulint	bit
	)

inline

Set a specific bit in flag.

Parameters

[in]	flag	bit flag
[in]	bit	set bit

Variable Documentation

◆ CLONE_DATA_FILE_IDX_OFFSET

const uint CLONE_DATA_FILE_IDX_OFFSET = CLONE_DATA_TASK_BLOCK_OFFSET + 4

static

Clone Data: Data file index in 4 bytes.

◆ CLONE_DATA_FILE_SIZE_OFFSET

const uint CLONE_DATA_FILE_SIZE_OFFSET = CLONE_DATA_FOFF_OFFSET + 8

static

Clone Data: Updated file size in 8 bytes.

◆ CLONE_DATA_FOFF_OFFSET

const uint CLONE_DATA_FOFF_OFFSET = CLONE_DATA_LEN_OFFSET + 4

static

Clone Data: Data file offset in 8 bytes.

◆ CLONE_DATA_LEN_OFFSET

const uint CLONE_DATA_LEN_OFFSET = CLONE_DATA_FILE_IDX_OFFSET + 4

static

Clone Data: Data length in 4 bytes.

◆ CLONE_DATA_STATE_OFFSET

const uint CLONE_DATA_STATE_OFFSET = CLONE_DESC_HEADER_LEN

static

Clone Data: Snapshot state in 4 bytes.

◆ CLONE_DATA_TASK_BLOCK_OFFSET

const uint CLONE_DATA_TASK_BLOCK_OFFSET

static

Initial value:

=

CLONE_DATA_TASK_CHUNK_OFFSET + 4

CLONE_DATA_TASK_CHUNK_OFFSET

static const uint CLONE_DATA_TASK_CHUNK_OFFSET

Clone Data: Current chunk number in 4 bytes.

Definition: clone0desc.cc:985

Clone Data: Current block number in 4 bytes.

◆ CLONE_DATA_TASK_CHUNK_OFFSET

const uint CLONE_DATA_TASK_CHUNK_OFFSET

static

Initial value:

=

CLONE_DATA_TASK_INDEX_OFFSET + 4

CLONE_DATA_TASK_INDEX_OFFSET

static const uint CLONE_DATA_TASK_INDEX_OFFSET

Clone Data: Task index in 4 bytes.

Definition: clone0desc.cc:982

Clone Data: Current chunk number in 4 bytes.

◆ CLONE_DATA_TASK_INDEX_OFFSET

const uint CLONE_DATA_TASK_INDEX_OFFSET = CLONE_DATA_STATE_OFFSET + 4

static

Clone Data: Task index in 4 bytes.

◆ CLONE_DESC_DATA_LEN

const uint CLONE_DESC_DATA_LEN = CLONE_DATA_FILE_SIZE_OFFSET + 8

static

Clone Data: Total length.

◆ CLONE_DESC_FILE_FLAG_AES

const uint CLONE_DESC_FILE_FLAG_AES = 3

static

Clone File Flag: Encryption type AES.

◆ CLONE_DESC_FILE_FLAG_DELETED

const uint CLONE_DESC_FILE_FLAG_DELETED = 5

static

Clone File Flag: File is deleted.

◆ CLONE_DESC_FILE_FLAG_LZ4

const uint CLONE_DESC_FILE_FLAG_LZ4 = 2

static

Clone File Flag: Compression type LZ4.

◆ CLONE_DESC_FILE_FLAG_RENAMED

const uint CLONE_DESC_FILE_FLAG_RENAMED = 4

static

Clone File Flag: File is renamed.

◆ CLONE_DESC_FILE_FLAG_ZLIB

const uint CLONE_DESC_FILE_FLAG_ZLIB = 1

static

Clone File Flag: Compression type ZLIB.

◆ CLONE_DESC_FILE_HAS_KEY

const uint CLONE_DESC_FILE_HAS_KEY = 6

static

Clone File Flag: File metadata has encryption key.

◆ CLONE_DESC_HEADER_LEN

const uint CLONE_DESC_HEADER_LEN = CLONE_DESC_TYPE_OFFSET + 4

static

Header: Fixed length.

◆ CLONE_DESC_LEN_OFFSET

const uint CLONE_DESC_LEN_OFFSET = CLONE_DESC_VER_OFFSET + 4

static

Header: Total length is stored in next 4 bytes.

◆ CLONE_DESC_LOC_BASE_LEN

const uint CLONE_DESC_LOC_BASE_LEN = CLONE_LOC_META_OFFSET + 1

static

Locator: Total length.

◆ CLONE_DESC_MAX_VERSION

const uint CLONE_DESC_MAX_VERSION = 100

static

Maximum supported descriptor version.

The version represents the current set of descriptors and its elements.

◆ CLONE_DESC_STATE_EST_BYTES

const uint CLONE_DESC_STATE_EST_BYTES = CLONE_DESC_STATE_NUM_FILES + 4

static

Clone State: Estimated number of bytes in 8 bytes.

◆ CLONE_DESC_STATE_EST_DISK

const uint CLONE_DESC_STATE_EST_DISK = CLONE_DESC_STATE_EST_BYTES + 8

static

Clone State: Estimated number of bytes in 8 bytes.

◆ CLONE_DESC_STATE_FLAG_ACK

const uint CLONE_DESC_STATE_FLAG_ACK = 2

static

Clone State Flag: Acknowledge processing state.

◆ CLONE_DESC_STATE_FLAG_START

const uint CLONE_DESC_STATE_FLAG_START = 1

static

Clone State Flag: Start processing state.

◆ CLONE_DESC_STATE_FLAGS

const uint CLONE_DESC_STATE_FLAGS = CLONE_DESC_STATE_EST_DISK + 8

static

Clone State: flags in 2 byte [max 16 flags].

◆ CLONE_DESC_STATE_LEN

const uint CLONE_DESC_STATE_LEN = CLONE_DESC_STATE_FLAGS + 2

static

Clone State: Total length.

◆ CLONE_DESC_STATE_NUM_CHUNKS

const uint CLONE_DESC_STATE_NUM_CHUNKS = CLONE_DESC_TASK_OFFSET + 4

static

Clone State: Number of chunks in 4 bytes.

◆ CLONE_DESC_STATE_NUM_FILES

const uint CLONE_DESC_STATE_NUM_FILES = CLONE_DESC_STATE_NUM_CHUNKS + 4

static

Clone State: Number of files in 4 bytes.

◆ CLONE_DESC_STATE_OFFSET

const uint CLONE_DESC_STATE_OFFSET = CLONE_DESC_HEADER_LEN

static

Clone State: Snapshot state in 4 bytes.

◆ CLONE_DESC_TASK_OFFSET

const uint CLONE_DESC_TASK_OFFSET = CLONE_DESC_STATE_OFFSET + 4

static

Clone State: Task index in 4 bytes.

◆ CLONE_DESC_TYPE_OFFSET

const uint CLONE_DESC_TYPE_OFFSET = CLONE_DESC_LEN_OFFSET + 4

static

Header: Descriptor type is in next 4 bytes.

◆ CLONE_DESC_VER_OFFSET

const uint CLONE_DESC_VER_OFFSET = 0

static

Header: Version is in first 4 bytes.

◆ CLONE_FILE_ALLOC_SIZE_OFFSET

const uint CLONE_FILE_ALLOC_SIZE_OFFSET = CLONE_FILE_SIZE_OFFSET + 8

static

File Metadata: Sparse file allocation size on disk in 8 bytes.

◆ CLONE_FILE_BASE_LEN

const uint CLONE_FILE_BASE_LEN = CLONE_FILE_FNAME_OFFSET

static

File Metadata: Length excluding the file name.

◆ CLONE_FILE_BCHUNK_OFFSET

const uint CLONE_FILE_BCHUNK_OFFSET = CLONE_FILE_IDX_OFFSET + 4

static

File Metadata: First chunk number in 4 bytes.

◆ CLONE_FILE_ECHUNK_OFFSET

const uint CLONE_FILE_ECHUNK_OFFSET = CLONE_FILE_BCHUNK_OFFSET + 4

static

File Metadata: Last chunk number in 4 bytes.

◆ CLONE_FILE_FLAGS_OFFSET

const uint CLONE_FILE_FLAGS_OFFSET = CLONE_FILE_FSBLK_OFFSET + 4

static

File Metadata: File space flags in next 2 bytes [Maximum 16 flags].

◆ CLONE_FILE_FNAME_OFFSET

const uint CLONE_FILE_FNAME_OFFSET = CLONE_FILE_FNAMEL_OFFSET + 4

static

File Metadata: File name.

◆ CLONE_FILE_FNAMEL_OFFSET

const uint CLONE_FILE_FNAMEL_OFFSET = CLONE_FILE_ECHUNK_OFFSET + 4

static

File Metadata: File name length in 4 bytes.

◆ CLONE_FILE_FSBLK_OFFSET

const uint CLONE_FILE_FSBLK_OFFSET = CLONE_FILE_FSP_OFFSET + 4

static

File Metadata: File system block size for compressed tables in 4 bytes.

◆ CLONE_FILE_FSP_OFFSET

const uint CLONE_FILE_FSP_OFFSET = CLONE_FILE_ALLOC_SIZE_OFFSET + 8

static

File Metadata: FSP flags in 4 bytes.

◆ CLONE_FILE_IDX_OFFSET

const uint CLONE_FILE_IDX_OFFSET = CLONE_FILE_SPACE_ID_OFFSET + 4

static

File Metadata: File index in 4 bytes.

◆ CLONE_FILE_SIZE_OFFSET

const uint CLONE_FILE_SIZE_OFFSET = CLONE_FILE_STATE_OFFSET + 4

static

File Metadata: File size in 8 bytes.

◆ CLONE_FILE_SPACE_ID_OFFSET

const uint CLONE_FILE_SPACE_ID_OFFSET = CLONE_FILE_FLAGS_OFFSET + 2

static

File Metadata: Tablespace ID in 4 bytes.

◆ CLONE_FILE_STATE_OFFSET

const uint CLONE_FILE_STATE_OFFSET = CLONE_DESC_HEADER_LEN

static

File Metadata: Snapshot state in 4 bytes.

◆ CLONE_LOC_CID_OFFSET

const uint CLONE_LOC_CID_OFFSET = CLONE_DESC_HEADER_LEN

static

Locator: Clone identifier in 8 bytes.

◆ CLONE_LOC_IDX_OFFSET

const uint CLONE_LOC_IDX_OFFSET = CLONE_LOC_SID_OFFSET + 8

static

Locator: Clone array index in 4 bytes.

◆ CLONE_LOC_META_OFFSET

const uint CLONE_LOC_META_OFFSET = CLONE_LOC_STATE_OFFSET + 1

static

Locator: Clone Snapshot sub-state in 1 byte.

◆ CLONE_LOC_SID_OFFSET

const uint CLONE_LOC_SID_OFFSET = CLONE_LOC_CID_OFFSET + 8

static

Locator: Snapshot identifier in 8 bytes.

◆ CLONE_LOC_STATE_OFFSET

const uint CLONE_LOC_STATE_OFFSET = CLONE_LOC_IDX_OFFSET + 4

static

Locator: Clone Snapshot state in 1 byte.

◆ CLONE_TASK_BLOCK_OFFSET

const uint CLONE_TASK_BLOCK_OFFSET = CLONE_TASK_CHUNK_OFFSET + 4

static

Task: Task block number in 4 bytes.

◆ CLONE_TASK_CHUNK_OFFSET

const uint CLONE_TASK_CHUNK_OFFSET = CLONE_TASK_INDEX_OFFSET + 4

static

Task: Task chunk number in 4 bytes.

◆ CLONE_TASK_INDEX_OFFSET

const uint CLONE_TASK_INDEX_OFFSET = CLONE_DESC_HEADER_LEN

static

Task: Clone task index in 4 bytes.

◆ CLONE_TASK_META_LEN

const uint CLONE_TASK_META_LEN = CLONE_TASK_BLOCK_OFFSET + 4

static

Task: Total length.

Functions

Variables

Detailed Description

Function Documentation

◆ choose_desc_version()

◆ clone_validate_locator()

◆ DESC_CHECK_FLAG()

◆ DESC_SET_FLAG()

Variable Documentation

◆ CLONE_DATA_FILE_IDX_OFFSET

◆ CLONE_DATA_FILE_SIZE_OFFSET

◆ CLONE_DATA_FOFF_OFFSET

◆ CLONE_DATA_LEN_OFFSET

◆ CLONE_DATA_STATE_OFFSET

◆ CLONE_DATA_TASK_BLOCK_OFFSET

◆ CLONE_DATA_TASK_CHUNK_OFFSET

◆ CLONE_DATA_TASK_INDEX_OFFSET

◆ CLONE_DESC_DATA_LEN

◆ CLONE_DESC_FILE_FLAG_AES

◆ CLONE_DESC_FILE_FLAG_DELETED

◆ CLONE_DESC_FILE_FLAG_LZ4

◆ CLONE_DESC_FILE_FLAG_RENAMED

◆ CLONE_DESC_FILE_FLAG_ZLIB

◆ CLONE_DESC_FILE_HAS_KEY

◆ CLONE_DESC_HEADER_LEN

◆ CLONE_DESC_LEN_OFFSET

◆ CLONE_DESC_LOC_BASE_LEN

◆ CLONE_DESC_MAX_VERSION

◆ CLONE_DESC_STATE_EST_BYTES

◆ CLONE_DESC_STATE_EST_DISK

◆ CLONE_DESC_STATE_FLAG_ACK

◆ CLONE_DESC_STATE_FLAG_START

◆ CLONE_DESC_STATE_FLAGS

◆ CLONE_DESC_STATE_LEN

◆ CLONE_DESC_STATE_NUM_CHUNKS

◆ CLONE_DESC_STATE_NUM_FILES

◆ CLONE_DESC_STATE_OFFSET

◆ CLONE_DESC_TASK_OFFSET

◆ CLONE_DESC_TYPE_OFFSET

◆ CLONE_DESC_VER_OFFSET

◆ CLONE_FILE_ALLOC_SIZE_OFFSET

◆ CLONE_FILE_BASE_LEN

◆ CLONE_FILE_BCHUNK_OFFSET

◆ CLONE_FILE_ECHUNK_OFFSET

◆ CLONE_FILE_FLAGS_OFFSET

◆ CLONE_FILE_FNAME_OFFSET

◆ CLONE_FILE_FNAMEL_OFFSET

◆ CLONE_FILE_FSBLK_OFFSET

◆ CLONE_FILE_FSP_OFFSET

◆ CLONE_FILE_IDX_OFFSET

◆ CLONE_FILE_SIZE_OFFSET

◆ CLONE_FILE_SPACE_ID_OFFSET

◆ CLONE_FILE_STATE_OFFSET

◆ CLONE_LOC_CID_OFFSET

◆ CLONE_LOC_IDX_OFFSET

◆ CLONE_LOC_META_OFFSET

◆ CLONE_LOC_SID_OFFSET

◆ CLONE_LOC_STATE_OFFSET

◆ CLONE_TASK_BLOCK_OFFSET

◆ CLONE_TASK_CHUNK_OFFSET

◆ CLONE_TASK_INDEX_OFFSET

◆ CLONE_TASK_META_LEN