igetput.c

来自「操作系统实验,文件系统,c语言实现的」· C语言 代码 · 共 191 行

#include <stdio.h>

#include "filesys.h"

struct inode * iget(dinodeid)    /*  iget()  */

unsigned int dinodeid;

{

   int existed=0,inodeid;

   long addr;

   struct inode *temp, *newinode;

   inodeid=dinodeid % NHINO;

  

   if(hinode[inodeid].i_forw==NULL)  existed=0;

   else

   {

    temp=hinode[inodeid].i_forw;

  

    while(temp)

    {

        if(temp->i_ino==inodeid)

       /*existed */

        {    existed=1;

            temp->i_count++;

            return temp;

        }

        /*not existed*/

        else

            temp=temp->i_forw;

   };

    }

    /*  not existed  */

   /*  1.  calculate the addr of the dinode in the file sys column  */

       addr=DINODESTART+dinodeid*DINODESIZ;

   /*  2.  malloc the new inode  */

       newinode=(struct inode *)malloc (sizeof (struct inode));

       /*  3.  read the dinode to the inode  */

       fseek(fd,addr,SEEK_SET);

       fread(&(newinode->di_number),DINODESIZ,1,fd);

   /*  4.  put it into hinode [inodeid]queue  */

    newinode->i_forw=hinode[inodeid].i_forw;

       newinode->i_back=newinode;

if(newinode->i_forw!=NULL)

       newinode->i_forw->i_back=newinode;

        hinode[inodeid].i_forw=newinode;

   /*   5.  initialize the inode  */

       newinode->i_count=1;

       newinode->i_flag=0;  /*f1ag for not update */

       newinode->i_ino=dinodeid;

        newinode->di_size=3*(DIRSIZ+2);

 if(dinodeid == 3) newinode->di_size=BLOCKSIZ;

   return newinode;

   }

  

   iput(pinode)    /*iput()*/

   struct inode * pinode;

   {

     long addr;

     unsigned int block_num;

     int i;

       

     if(pinode->i_count>1)

     {

       pinode->i_count--;

        return;

     }

     else

     {

  

          if(pinode->di_number!=0)

       {

             /*  write back the inode  */

           addr=DINODESTART+pinode->i_ino*DINODESIZ;

           fseek(fd,addr,SEEK_SET);

           fwrite(&pinode->di_number,DINODESIZ,1,fd);

        }

        else  

        {

         /*  rm the inode & the block of the file in the disk  */

         block_num=pinode->di_size/BLOCKSIZ;

         for(i=0;i<block_num;i++)

         {

            bfree(pinode->di_addr[i]);

         }

         ifree(pinode->i_ino);

       };

  

       /*  free the inode in the memory  */

       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;

        };

       ifree(pinode);

    };

 }