hos/kernel/fs/ext2/Ext2BlockCache.cpp

// Ext2BlockCache.cpp
// Author: Josh Holtrop
// Date: 12/29/05
// Modified: 12/29/05

#include "fs/vfs.h"
#include "Ext2BlockCache.h"

extern "C" {
#include "display/kout.h"
}

Ext2BlockCache::Ext2BlockCache(Ext2fs *fs, u32_t inum)
{
	myFS = fs;
	myInum = inum;
	myInodeDirty = 0;
	fs->readInode(inum, &myInode);
	myBlockSize = 1024 << fs->getSuper()->s_log_block_size;
	for (int i = 0; i < 3; i++)
	{
		myCache[i] = new u8_t[myBlockSize];
		myCacheAddress[i] = 0;
		myCacheDirty[i] = 0;
	}
}

Ext2BlockCache::~Ext2BlockCache()
{
	for (int i = 0; i < 3; i++)
	{
		if (myCacheDirty[i])
			myFS->writeBlock(myCacheAddress[i], myCache[i]);
		delete[] myCache[i];
	}
	if (myInodeDirty)
		myFS->writeInode(myInum, &myInode);
}

int	Ext2BlockCache::readBlock(u32_t blockNum, void *buf)
{
	u32_t fsblock = getFSBlock(blockNum, 0);
	if (fsblock == 0)
		return -1;
	return myFS->readBlock(fsblock, buf);
}

int	Ext2BlockCache::writeBlock(u32_t blockNum, void *buf)
{
	u32_t fsblock = getFSBlock(blockNum, 1);
	if (fsblock == 0)
		return -1;
	return myFS->writeBlock(fsblock, buf);
}

void	Ext2BlockCache::setCache(u32_t level, u32_t fsblock)
{
	if (myCacheAddress[level] == fsblock)
		return;
	if (myCacheDirty[level])
		myFS->writeBlock(myCacheAddress[level], myCache[level]);
	myCacheAddress[level] = fsblock;
	myCacheDirty[level] = 0;
	myFS->readBlock(fsblock, myCache[level]);
}

u32_t	Ext2BlockCache::getFSBlock(u32_t blockNum, int create)
{
	if (blockNum < 12)				/* direct pointer */
	{
		if (create && myInode.i_block[blockNum] == 0)
		{
			myInode.i_block[blockNum] = myFS->allocBlock();
			myInodeDirty = 1;
		}
		return myInode.i_block[blockNum];
	}
	blockNum -= 12;
	if (blockNum < myBlockSize)			/* i_block[12] */
	{
		if (create && myInode.i_block[12] == 0)
		{
			myInode.i_block[12] = myFS->allocBlock();
			myInodeDirty = 1;
		}
		setCache(0, myInode.i_block[12]);
		/* blockNum indexes cache 0 */
		if (create && myCache[0][blockNum] == 0)
		{
			myCache[0][blockNum] = myFS->allocBlock();
			myCacheDirty[0] = 1;
		}
		return myCache[0][blockNum];
	}
	blockNum -= myBlockSize;
	if (blockNum < (myBlockSize * myBlockSize))	/* i_block[13] */
	{
		if (create && myInode.i_block[13] == 0)
		{
			myInode.i_block[13] = myFS->allocBlock();
			myInodeDirty = 1;
		}
		setCache(0, myInode.i_block[13]);
		/* blockNum / myBlockSize indexes cache 0 */
		if (create && myCache[0][blockNum / myBlockSize] == 0)
		{
			myCache[0][blockNum / myBlockSize] = myFS->allocBlock();
			myCacheDirty[0] = 1;
		}
		setCache(1, myCache[0][blockNum / myBlockSize]);
		/* blockNum % myBlockSize indexes cache 1 */
		if (create && myCache[1][blockNum % myBlockSize] == 0)
		{
			myCache[1][blockNum % myBlockSize] = myFS->allocBlock();
			myCacheDirty[1] = 1;
		}
		return myCache[1][blockNum % myBlockSize];
	}
	blockNum -= (myBlockSize * myBlockSize);	/* i_block[14] */
	if (create && myInode.i_block[14] == 0)
	{
		myInode.i_block[14] = myFS->allocBlock();
		myInodeDirty = 1;
	}
	setCache(0, myInode.i_block[14]);
	/* blockNum / (myBlockSize^2) indexes cache 0 */
	if (create && myCache[0][blockNum / (myBlockSize * myBlockSize)] == 0)
	{
		myCache[0][blockNum / (myBlockSize * myBlockSize)] = myFS->allocBlock();
		myCacheDirty[0] = 1;
	}
	setCache(1, myCache[0][blockNum / (myBlockSize * myBlockSize)]);
	/* blockNum / myBlockSize indexes cache 1 */
	if (create && myCache[1][blockNum / myBlockSize] == 0)
	{
		myCache[1][blockNum / myBlockSize] = myFS->allocBlock();
		myCacheDirty[1] = 1;
	}
	setCache(2, myCache[1][blockNum / myBlockSize]);
	/* blockNum % myBlockSize indexes cache 2 */
	if (create && myCache[2][blockNum % myBlockSize] == 0)
	{
		myCache[2][blockNum % myBlockSize] = myFS->allocBlock();
		myCacheDirty[2] = 1;
	}
	return myCache[2][blockNum % myBlockSize];
}