/*
* Copyright (c) 2020 Red Hat, Inc.
*
* 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; either version 2
* of the License, or (at your option) any later version.
*
* 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, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* $Id: //eng/vdo-releases/aluminum/src/c++/vdo/base/referenceBlock.h#1 $
*/
#ifndef REFERENCE_BLOCK_H
#define REFERENCE_BLOCK_H
#include "constants.h"
#include "journalPoint.h"
#include "types.h"
#include "waitQueue.h"
/**
* A type representing a reference count.
**/
typedef uint8_t ReferenceCount;
/**
* Special ReferenceCount values.
**/
enum {
EMPTY_REFERENCE_COUNT = 0,
MAXIMUM_REFERENCE_COUNT = 254,
PROVISIONAL_REFERENCE_COUNT = 255,
};
enum {
COUNTS_PER_SECTOR = ((VDO_SECTOR_SIZE - sizeof(PackedJournalPoint))
/ sizeof(ReferenceCount)),
COUNTS_PER_BLOCK = COUNTS_PER_SECTOR * SECTORS_PER_BLOCK,
};
/**
* The format of a ReferenceSector on disk.
**/
typedef struct {
PackedJournalPoint commitPoint;
ReferenceCount counts[COUNTS_PER_SECTOR];
} __attribute__((packed)) PackedReferenceSector;
typedef struct {
PackedReferenceSector sectors[SECTORS_PER_BLOCK];
} PackedReferenceBlock;
/*
* ReferenceBlock structure
*
* Blocks are used as a proxy, permitting saves of partial refcounts.
**/
typedef struct {
/** This block waits on the refCounts to tell it to write */
Waiter waiter;
/** The parent RefCount structure */
RefCounts *refCounts;
/** The number of references in this block that represent allocations */
BlockSize allocatedCount;
/** The slab journal block on which this block must hold a lock */
SequenceNumber slabJournalLock;
/**
* The slab journal block which should be released when this block
* is committed
**/
SequenceNumber slabJournalLockToRelease;
/** The point up to which each sector is accurate on disk */
JournalPoint commitPoints[SECTORS_PER_BLOCK];
/** Whether this block has been modified since it was written to disk */
bool isDirty;
/** Whether this block is currently writing */
bool isWriting;
} ReferenceBlock;
#endif // REFERENCE_BLOCK_H