igetput.h

Linux 的最重要的特徵之一是它的为许多不同的文件系统的支持。这使其非常灵活从而与许多另外的操作系统可以很好的共存。linux采用的是树型结构。最上层是根目录

struct inode *iget(unsigned int dinodeid)
{
	int existed=0,inodeid;
	long addr;
	struct inode *temp,*newinode;

	
	inodeid=dinodeid%NHINO;
	if(hinode[inodeid].i_forw==NULL) temp=&hinode[inodeid];
	else
	{
		temp=hinode[inodeid].i_forw;
		while(temp->i_forw)
		{
			if((int)temp->i_ino==inodeid)
			{
				existed=1;
				temp->i_count++;
				return temp;
			}
			else
				temp=temp->i_forw;
		};
	}
	addr=DINODESTART+dinodeid*DINODESIZ;
	newinode=(struct inode*)malloc(sizeof(struct inode));
	fseek(fd,addr,SEEK_SET);
	fread(newinode,DINODESIZ,1,fd);

	if(hinode[inodeid].i_forw==NULL)
	{
		newinode->i_forw=hinode[inodeid].i_forw;	
		hinode[inodeid].i_forw=newinode;
		newinode->i_back=&(hinode[inodeid]);
	}
	else
	{
		newinode->i_forw=hinode[inodeid].i_forw;	
		hinode[inodeid].i_forw=newinode;
		newinode->i_back=newinode->i_forw->i_back;
		newinode->i_forw->i_back=newinode;
	}
	
	newinode->i_count=1;
	newinode->i_flag=0;
	newinode->i_ino=dinodeid;
	fseek(fd,addr,SEEK_SET);
	fwrite(newinode,DINODESIZ,1,fd);
	
	return newinode;
}
iput(struct inode *pinode)
{
	long addr;
	unsigned int block_num;
	int i;

	if(pinode->i_count>1)
	{
		pinode->i_count--;
	}
	else
	{
		if(pinode->di_number!=0)
		{
			addr=DINODESTART+pinode->i_ino*DINODESIZ;
			fseek(fd,addr,SEEK_SET);
			fwrite(pinode,DINODESIZ,1,fd);
		}
		else
		{
			block_num=pinode->di_size/BLOCKSIZ;
			for(i=0;i<(int)block_num;i++)
			{
				balloc(pinode->di_addr[i]);
			}
			ifree(pinode->i_ino);
		};
		if(pinode->i_forw==NULL)
			pinode->i_back->i_forw=NULL;
		else
		{
			pinode->i_forw->i_back=pinode->i_back;
			pinode->i_back->i_forw=pinode->i_forw;
		};
		free(pinode);
	};
}