iallfre.c

#include "stdio.h"
#include "filesys.h"

static struct dinode block_buf[BLOCKSIZ / DINODESIZ];

struct inode *ialloc() /*ialloc */
{
  struct inode *temp_inode;
  unsigned int cur_di;
  int i, count, block_end_flag;

  if (filsys.s_pinode == NICINOD) /*s_inode empty */
  {
    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]);  //分配内存i节点
  temp_inode->i_ino = filsys.s_inode[filsys.s_pinode]; //设置磁盘i节点号
  fseek(fd, DINODESTART + filsys.s_inode[filsys.s_pinode] * sizeof(struct dinode), SEEK_SET);
  fwrite(&temp_inode->di_number, 1, sizeof(struct dinode), fd);

  ++filsys.s_pinode;
  --filsys.s_ninode; //磁盘i结点总数-1，置超级块修改标志，返回
  filsys.s_fmod = SUPDATE;

  return temp_inode;
}

void ifree(unsigned dinodeid) /*ifree*/
{
  filsys.s_ninode++;
  if (filsys.s_pinode != NICINOD) /*not full*/
  {
    filsys.s_inode[filsys.s_pinode] = dinodeid;
    filsys.s_pinode++;
  }
  else /*full*/
      if (dinodeid < filsys.s_rinode)
  {
    filsys.s_inode[NICINOD] = dinodeid;
    filsys.s_rinode = dinodeid;
  }
}