块设备驱动2.6.32内核，解决挂载后死机hang住

应该注意版本更新函数的变化。

内核版本：2.6.32-24-generic

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/genhd.h>
#include <linux/blkdev.h>

#define BLKDEV_DISKNAME "blkdev"
/*
 使用的一个并不常用的设备号，也可动态申请
 dev_major = register_blkdev(0, BLKDEV_DISKNAME); //在/proc/devices/下面的名称
 需检查申请是否成功
*/
#define BLKDEV_DEVICEMAJOR COMPAQ_SMART2_MAJOR
#define BLKDEV_BYTES (16*1024*1024) //16M

unsigned char blkdev_data[BLKDEV_BYTES];

static struct gendisk *blkdev_disk;
static struct request_queue *blkdev_queue;

struct block_device_operations blkdev_fops = {
 .owner = THIS_MODULE,
};

static void blkdev_do_request(struct request_queue *q)
{
 struct request *req;
 req = blk_fetch_request(q); //函数链blk_fetch_request()->blk_peek_request()->__elv_next_request()->...

 while(req) {
  unsigned long start = blk_rq_pos(req) << 9;
  unsigned long len = blk_rq_cur_sectors(req) << 9; //此处等同于len = blk_rq_cur_bytes(req);
  int err = 0;

  if(start + len > BLKDEV_BYTES) {
   printk(KERN_ERR BLKDEV_DISKNAME ":bad access:block=%lu,count=%un",blk_rq_pos(req), blk_rq_cur_sectors(req));
   err = -EIO;
   goto done;
  }
  if(rq_data_dir(req) == READ)
   memcpy(req->buffer, blkdev_data+start,len);
  else
   memcpy(blkdev_data+start, req->buffer, len);
 done:
  if(!__blk_end_request_cur(req, err))
   req = blk_fetch_request(q);
 }
}

static int __init blkdev_init(void)
{
 int ret;

 blkdev_queue = blk_init_queue(blkdev_do_request, NULL); //每个块设备关联请求处理函数
 if(!blkdev_queue) {
  ret = -ENOMEM;
  goto err_init_queue;
 }

 blkdev_disk = alloc_disk(1);
 if(!blkdev_disk) {
  goto err_alloc_disk;
 }
 strcpy(blkdev_disk->disk_name, BLKDEV_DISKNAME); //在/dev/下面的名称
 blkdev_disk->major = BLKDEV_DEVICEMAJOR; //如果是动态申请的话就是dev_major
 blkdev_disk->first_minor = 0;
 blkdev_disk->fops = &blkdev_fops;
 blkdev_disk->queue = blkdev_queue;
 set_capacity(blkdev_disk, BLKDEV_BYTES>>9); //扇区大小512B
 add_disk(blkdev_disk);

 return 0;

err_alloc_disk:
 blk_cleanup_queue(blkdev_queue);
err_init_queue:
 return ret;

}

static void __exit blkdev_exit(void)
{
 blk_cleanup_queue(blkdev_queue);
 del_gendisk(blkdev_disk);
 put_disk(blkdev_disk);
}

module_init(blkdev_init);
module_exit(blkdev_exit);

2012-02-18 23:15 发表于百度空间，今搬至CU。