iallfre.c

操作系统课程设计

/* i节点分配与释放函数*/

#include <stdio.h>
#include "filesys.h"

static struct dinode block_buf[BLOCKSIZ/DINODESIZ];

struct inode * ialloc()
{

	struct inode * temp_inode;
	unsigned int cur_di;
	int i, count, block_end_flag;
	
	if (filsys. s_pinode== NICINOD)
	{
			i=0;
			count = 0;
			block_end_flag= 1;
			filsys.s_pinode=NICINOD-1;
			cur_di=filsys.s_rinode;
		while ((count <NICINOD)||(count <=filsys.s_ninode))
		{
			if (block_end_flag)
			{
				fseek(fd,DINODESTART+cur_di*DINODESIZ,SEEK_SET);
				fread(block_buf, 1,BLOCKSIZ,fd);
				block_end_flag=0;
				i=0;
			}
			while (block_buf[i].di_mode != DIEMPTY)
			{
				cur_di++;
				i++;
			}
			if (i==NICINOD)
				block_end_flag=1;
			else
			{
				filsys.s_inode[filsys.s_pinode--]= cur_di;
				count++;
			}
		}
		filsys.s_rinode=cur_di;
	}
	temp_inode=iget(filsys.s_inode[filsys.s_pinode]);
	fseek (fd, DINODESTART+filsys.s_inode[filsys.s_pinode]* DINODESIZ,SEEK_SET);
	fwrite (&temp_inode->di_number,1,sizeof (struct dinode), fd);
	filsys.s_pinode++;
	filsys.s_ninode--;
	filsys.s_fmod =SUPDATE;
	return temp_inode;
}


ifree(dinodeid)	 /* ifree */
unsigned dinodeid;
{
filsys.s_ninode++;
if (filsys.s_pinode != NICINOD)    /* notfull */
{    
	filsys.s_pinode --;
	filsys.s_inode[filsys.s_pinode]=dinodeid;
	
}
else /* full */
{
	if (dinodeid <filsys.s_rinode)
	{
		filsys.s_inode[NICINOD] =dinodeid;
		filsys.s_rinode=dinodeid;
	}
}

}