奇怪的ext3文件组织结构显示

gxqing

我通过如下方式取得了/分区的supper_block及group_desc 块的内容,结果显示好奇怪啊!


open /dev/hda3!
inode_per_group is 16096
s_inodes_count is 595552
s_free_inodes_count is 386527
s_free_blocks_count is 221056
block size is 4096 byte
blocks_count is 1188810
first_data_block is 0
blocks_per_group is 32768
total group is 37
inode_per_block is 32
inode_bit_blocks is 503
volume name is /

bg_block_bitmap is 2
bg_inode_bitmap is 3
bg_inode_table is 4
bg_free_blocks_count is 0
bg_free_inodes_count is 10424
group_count=0
bg_block_bitmap is 32770
bg_inode_bitmap is 32771
bg_inode_table is 32772
bg_free_blocks_count is 2
bg_free_inodes_count is 10449
group_count=1

bg_block_bitmap is 65536  //????
bg_inode_bitmap is 65537 //????
bg_inode_table is 65540  
bg_free_blocks_count is 0
bg_free_inodes_count is 10443
group_count=2
bg_block_bitmap is 98306
bg_inode_bitmap is 98307
bg_inode_table is 98308
bg_free_blocks_count is 0
bg_free_inodes_count is 10438
group_count=3
bg_block_bitmap is 131072  //????
bg_inode_bitmap is 131073 //????
bg_inode_table is 131076   
bg_free_blocks_count is 0
bg_free_inodes_count is 8243
group_count=4

.......
打问号的地方感觉不对呀?每个组的第一个应该是supper_block,然后是group_desc,然后才是block_bitmap和inode_bitmap,为什么在这里显示的会有这种奇怪的情况呢?


我的读取程序如下,感觉没有问题?

FILE  *fp;              /*定义文件指针*/  
  char info[1024];
  if((fp=fopen("/dev/hda2","rb"))==NULL){
    printf("open /dev/hda2 failure!\n");
    exit(1);
  }else
    printf("open /dev/hda2!\n");
  fseek(fp,1024,0);  
  fread(info,sizeof(s_block),1,fp);  
  p_block=info;

//超级块的内容分解
  printf("inode_per_group is %d \n",p_block->s_inodes_per_group);
  printf("s_inodes_count is %d \n",p_block->s_inodes_count);
  printf("s_free_inodes_count is %d \n",p_block->s_free_inodes_count);
  printf("s_free_blocks_count is %d \n",p_block->s_free_blocks_count);
  printf("block size is %d byte\n",1<<(p_block->s_log_block_size+10));//一个数据块的大小
  printf("blocks_count is %d \n",p_block->s_blocks_count);//分区总块数
  printf("first_data_block is %d \n",p_block->s_first_data_block);//第一个数据块号
  printf("blocks_per_group is %d \n",p_block->s_blocks_per_group);//每个块组的块数
  printf("total group is %d \n",(p_block->s_blocks_count-p_block->s_first_data_block-1)/p_block->s_blocks_per_group+1);//这个分区的块组数
  
  //每个块可以存放的索引节点数
  unsigned long inode_per_block=(1<<(p_block->s_log_block_size+10))/128;
  printf("inode_per_block is %d \n",inode_per_block);
  
  //索引节点表占用空间的计算
  printf("inode_bit_blocks is %d \n",p_block->s_inodes_per_group/inode_per_block);
  printf("volume name is %s \n",p_block->s_volume_name);//卷标名
  printf("last mounted directory is %s \n",p_block->s_last_mounted);


  char info1[2048];
  fseek(fp,4096,0);  
  fread(info1,2048,1,fp);
  int group_count;
  
  for(group_count=0;group_count<37;group_count++)
  {      
       p_dec=info1+group_count*32;
      
       //块描述结构的内容分解
       printf("bg_block_bitmap is %d \n",p_dec->bg_block_bitmap);//节点总数
       printf("bg_inode_bitmap is %d \n",p_dec->bg_inode_bitmap);
       printf("bg_inode_table is %d \n",p_dec->bg_inode_table);
       printf("bg_free_blocks_count is %d \n",p_dec->bg_free_blocks_count);
       printf("bg_free_inodes_count is %d \n",p_dec->bg_free_inodes_count);  
       printf("group_count=%d \n",group_count);
  }