下面的程序可以在linux2.6内核直接读写硬盘的指定扇区，也是根据网上一个朋友的做法做了修改的；

有两个不是很明白的地方就是：1、bd_claim函数的使用，这个是个递归函数，像是匹配内存指针和设备，但是调用会返回错误；2、bdev = open_by_devnum(0x00800000, FMODE_READ | FMODE_WRITE); 中0x00800000数字的确认，不知从何而来：

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/msdos_fs.h>
#include <linux/fcntl.h>
#include <linux/delay.h>

static int set_size = 512;
static int nr = 0;

static char pages_addr[PAGE_SIZE];
static char pages_write_addr[PAGE_SIZE];

module_param(set_size,int,S_IRUGO);
MODULE_PARM_DESC(set_size,"how many bytes you want to read,not more than 4096");

module_param(nr,long,S_IRUGO);
MODULE_PARM_DESC(nr,"which sectors you want to read");

MODULE_LICENSE("GPL");

static struct block_device *bdev;
static char *usage = "You can change the value:set_size nr devn";

int bdev_write_one_page(struct block_device *bdev, unsigned long blocknr, void *page_addr)
{
 int ret = -1;
 struct buffer_head *bh;
 if (!bdev || !page_addr)
 {
  printk("%s error ", __func__);
  return -1;
 }
 bh = __getblk(bdev, blocknr, PAGE_SIZE);
 if (!bh)
 {
  printk("get blk failed ");
  return -1;
 }
 memcpy(bh->b_data, page_addr, PAGE_SIZE);
 mark_buffer_dirty(bh);
 ll_rw_block(WRITE, 1, &bh);
 
 brelse(bh);
 ret = 0;
 return ret;
}

int bdev_read_one_page(struct block_device *bdev, unsigned long blocknr, void *page_addr)
{
 int ret = -1;
 struct buffer_head *bh;
 if (!bdev || !page_addr)
 {
  printk("%s error ", __func__);
  return -1;
 }

bh = __getblk(bdev, blocknr, PAGE_SIZE);
 if (!bh)
 {
  printk("get blk failed ");
  return -1;
 }

if (!buffer_uptodate(bh))
 {
  ll_rw_block(READ, 1, &bh);
  wait_on_buffer(bh);
  if (!buffer_uptodate(bh))
  {
   ret = -1;
   goto out;
  }
 }
 memcpy(page_addr, bh->b_data, PAGE_SIZE);
 ret = 0;

out:
 brelse(bh);

return ret;
}

void block_test(void)
{
 struct block_device *bdev;
// void *pages_addr = (void *)kmalloc(2048,GFP_KERNEL);
 void *holder = (void *)pages_addr;
 int cnt, ret;
 int blocknr;
 //bdev = bdget(MKDEV(16, 0));
 int i = 0;
 
 printk("block_test:IN ---------2010-03-22\n");
 //memset(pages_addr,0x00,sizeof(pages_addr));
 printk("pages_addr:%x\n",pages_addr);
 printk("holder:%x\n",holder);
#if 1

bdev = open_by_devnum(0x00800000, FMODE_READ | FMODE_WRITE);
    //    bdev=0x800;
 if (IS_ERR(bdev))
 {
  printk("bdget error, bdev=%08lx \n", (unsigned long)bdev);
  return;
 }
 printk("bdev:%x\n",bdev);
 bdev->bd_holder = holder;
#if 0
 if (bd_claim(bdev, holder))
 {
  printk("claim failed \n");
  goto out_bdev;
 } 
 printk("after bd_claim\n");
#endif 
#if 0
// blocknr = *(unsigned long *)(pages_addr + 0x100000);
 //for (cnt = 0; cnt < 10 * 1024; cnt++, blocknr++)
 {
  printk("nr=%d\n",nr);
  memset(pages_addr,0xff,PAGE_SIZE);
  ret = bdev_read_one_page(bdev,nr, (void *)pages_addr);
  if (ret)
   printk("blk read failed ");

}
 printk("after bdev_read_one_page\n");
// printk("get data:%0x,%0x\n,",pages_addr[510],pages_addr[511]);
 for( i = 0; i < 512; i++ )   
 {       
  printk( "%02x ",(unsigned char)pages_addr[ i ] );       
  if(( i % 16  ) == 15)       
  {           
   printk( "  \n" );       
  }   
 }   
 printk( "  \n" );

printk("nr=%d\n",nr);
 memset(pages_write_addr,0xe7,PAGE_SIZE);
 ret = bdev_write_one_page(bdev,nr, (void *)pages_write_addr);
 if (ret)
  printk("blk write failed ");
#endif
 {
  printk("nr=%d\n",nr);
  ret = bdev_read_one_page(bdev,nr, (void *)pages_addr);
  if (ret)
   printk("blk read failed ");

}
 printk("after bdev_read_one_page\n");
// printk("get data:%0x,%0x\n,",pages_addr[510],pages_addr[511]);
 for( i = 0; i < 512; i++ )   
 {       
  printk( "%02x ",(unsigned char)pages_addr[ i ] );       
  if(( i % 16  ) == 15)       
  {           
   printk( "  \n" );       
  }   
 }   
 printk( "  \n" );

out_bdev:
// bd_release(bdev);
 
// blkdev_put(bdev,FMODE_READ | FMODE_WRITE);
 blkdev_put(bdev);
#endif
 return;
}
static int __init disk_rw_init(void)
{
// nr = 0;
// set_size = PAGE_SIZE;

block_test();

return 0;
}
static void __exit disk_rw_exit(void)
{
 printk("disk_rw_exit\n");
 
}

module_init(disk_rw_init);
module_exit(disk_rw_exit);

Makefile:

ifneq ($(KERNELRELEASE),)
 obj-m:=hw_disk_rw26.o
else
 KDIR =/usr/src/linux-2.6.33
#       KDIR = /usr/src/kernels/2.6.9-5.EL-i686
 PWD:=$(shell pwd)
default:
 $(MAKE) -C $(KDIR) M=$(PWD) modules
install:
 insmod hw_disk_rw26.ko
uninstall:
 rmmod hw_disk_rw26.ko
clean:
 $(MAKE) -C $(KDIR) M=$(PWD) clean

endif