[原创] 写一个块设备驱动

ChiyuT

楼主能做成一个pdf不？实在是上网没时间。只能下载了看。

blindkey

看完了两遍...今天自己动手就悲剧了...

毕竟是时间过去一段时间了  块设备部分也有了变化，自己查了查，

然后编译通过了  但是加载就悲剧····还是第一章····这不是打击我积极性么····

楼主能给看看不....

1. #include <linux/init.h>
   
2. #include <linux/module.h>
   
3. #include <linux/blkdev.h>
   
4. 
   
5. MODULE_LICENSE("Dual BSD/GPL");
   
6. 
   
7. #define MY_BLKDEV_DEVICEMAJOR COMPAQ_SMART2_MAJOR
   
8. #define MY_BLKDEV_DISKNAME "mydisk"
   
9. #define MY_BLKDEV_SIZE (16*1024*1024)
   
10. 
    
11. static struct request_queue *my_blkdev_queue;
    
12. static struct gendisk *my_blkdev_disk;
    
13. unsigned char my_blkdev_data[MY_BLKDEV_SIZE];
    
14. 
    
15. static void my_blkdev_do_request(struct request_queue *q);
    
16. 
    
17. struct block_device_operations my_blkdev_fops ={ .owner = THIS_MODULE,};
    
18. 
    
19. static int __init my_blkdev_init(void )
    
20. {
    
21.    
    
22.     int ret;
    
23.     printk(KERN_ALERT MY_BLKDEV_DISKNAME"init!");
    
24.     my_blkdev_queue = blk_init_queue(my_blkdev_do_request,NULL);
    
25.     if(!my_blkdev_queue){
    
26.         ret = -ENOMEM;
    
27.         goto err_init_queue;
    
28.     }
    
29.     my_blkdev_disk = alloc_disk(1);
    
30.     if(!my_blkdev_disk){
    
31.         ret = -ENOMEM;
    
32.         goto err_alloc_disk;
    
33.     }
    
34.     strcpy(my_blkdev_disk->disk_name,MY_BLKDEV_DISKNAME);
    
35.     my_blkdev_disk->major = MY_BLKDEV_DEVICEMAJOR;
    
36.     my_blkdev_disk->fops = & my_blkdev_fops;
    
37.     my_blkdev_disk->queue = my_blkdev_queue;
    
38.     set_capacity(my_blkdev_disk,MY_BLKDEV_SIZE>>9);
    
39.     add_disk(my_blkdev_disk);
    
40.     return 0;
    
41. 
    
42. err_alloc_disk:
    
43.     blk_cleanup_queue(my_blkdev_queue);
    
44. 
    
45. err_init_queue:
    
46.     return ret;
    
47. 
    
48. }
    
49. 
    
50. static void my_blkdev_exit(void)
    
51. {
    
52. 
    
53.         printk(KERN_ALERT"exit modules blk!");
    
54.     del_gendisk(my_blkdev_disk);
    
55.     blk_cleanup_queue(my_blkdev_queue);
    
56. }
    
57. 
    
58. static void my_blkdev_do_request(struct request_queue *q)
    
59. {
    
60.     struct request *req;
    
61.     while((req=blk_fetch_request(q))!=NULL){
    
62.         if((blk_rq_pos(req)+blk_rq_sectors(req))<<9 >MY_BLKDEV_SIZE){
    
63.             printk(KERN_ERR MY_BLKDEV_DISKNAME"bad request :block =%llu,count=%u\n",(u64) blk_rq_pos(req),blk_rq_sectors( req));
    
64.             __blk_end_request_all(req,-EIO);
    
65.             continue;
    
66.         }
    
67.         switch( rq_data_dir(req)){
    
68.             case READ:
    
69.                 printk(KERN_ALERT "read\n");
    
70.                 memcpy(req->buffer,my_blkdev_data+(blk_rq_pos(req)<<9),blk_rq_sectors(req)<<9);
    
71.                 __blk_end_request_all(req,1);
    
72.                 break;
    
73.             case WRITE:
    
74.                 printk(KERN_ALERT "write\n");
    
75.                 memcpy(my_blkdev_data+(blk_rq_pos(req)<<9),req->buffer,blk_rq_sectors(req)<<9);
    
76.                 __blk_end_request_all(req,1);                break;
    
77.             default:
    
78.                 printk(KERN_ALERT "this should not happen");
    
79.                 break;
    
80.         }
    
81.     }
    
82. }
    
83. module_init(my_blkdev_init);
    
84. module_exit(my_blkdev_exit);
    
85. 
    

复制代码

blindkey

环境：ubuntu 10.04tls
内核 :2.6.36.2
gcc:4.4.3

lilikoo

lz，我拿你第一章的代码在我电脑上编译，出现以下错误：
make -C /lib/modules/2.6.37.2+/build SUBDIRS=/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01 modules
make[1]: Entering directory `/usr/src/linux-2.6.37.2'
  CC [M]  /data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.o
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c: In function 'simp_blkdev_do_request':
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:43: error: implicit declaration of function 'elv_next_request'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:43: warning: assignment makes pointer from integer without a cast
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:44: error: 'struct request' has no member named 'sector'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:44: error: 'struct request' has no member named 'current_nr_sectors'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:48: error: 'struct request' has no member named 'sector'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:49: error: 'struct request' has no member named 'current_nr_sectors'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:50: error: implicit declaration of function 'end_request'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:57: error: 'struct request' has no member named 'sector'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:58: error: 'struct request' has no member named 'current_nr_sectors'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:62: error: 'struct request' has no member named 'sector'
/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.c:63: error: 'struct request' has no member named 'current_nr_sectors'
make[2]: *** [/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01/simp_blkdev.o] Error 1
make[1]: *** [_module_/data/home/likuo/blockdrive/simp_blkdev/simp_blkdev_step01] Error 2
make[1]: Leaving directory `/usr/src/linux-2.6.37.2'
make: *** [default] Error 2

我的内核是Linux－2.6.37.2
我于是在内核里找相应结构，发现struct request里没有sector和current_nr_sectors成员，也没发现elv_next_reques和end_request函数；
是不是它们改名字了，还是在哪地方弄错了；
我是菜鸟，上网上也没找到答案，请lz帮帮忙，谢谢

blindkey

回复 194# lilikoo


    改名字了   


具体看linux/include/blkdev.h

sectors    ------------- >   blk_rq_pos

nr_sectros   --------------- > blk_rq_sectors

__elv_next_request              -------------------->       blk_peek_request

lilikoo

谢谢blinkkey，我改了一些地方：
sectors调用blk_rq_pos得到
current_nr_sectors调用blk_rq_sectors得到
elv_next_request换成blk_peek_request
end_request换成blk_end_request_cur
终于编译成功了，太高兴了；
于是我insmod simp_blkdev.ko;
悲剧了，机器宕了，自动重启

loover217

我也碰到楼上的问题，哪位大牛解释一下原因啊，谢谢。。。

wibnmo

一加载模块就死机，什么原因？哪位给分析下，谢谢了。

1. 
   
2. #include <linux/init.h>
   
3. #include <linux/module.h>
   
4. #include <linux/blkdev.h>
   
5. 
   
6. #define KERNEL_SECTOR_SIZE        512
   
7. 
   
8. static int sbull_major = 0;
   
9. static struct request_queue *request;
   
10. static struct gendisk *gd;
    
11. 
    
12. static int nsectors = (16*1024*1024) >> 9;
    
13. static int hardsect_size = 512;
    
14. 
    
15. unsigned char sbull_data[16*1024*1024];
    
16. 
    
17. static struct block_device_operations sbull_fops = {
    
18.         .owner        =        THIS_MODULE,
    
19. };
    
20. 
    
21. static void sbull_request(struct request_queue *q)
    
22. {
    
23.         int err;
    
24.         struct request *req;
    
25.         unsigned int sector, current_nr_sectors;
    
26.        
    
27.         req = blk_peek_request(q);
    
28.         sector = blk_rq_pos(req);
    
29.         current_nr_sectors = blk_rq_sectors(req);
    
30. 
    
31.         switch (rq_data_dir(req)) {
    
32. 
    
33.         case READ:
    
34.                 memcpy(req->buffer, sbull_data + (sector << 9), current_nr_sectors << 9);
    
35.                 blk_end_request_cur(req, err);
    
36.                 break;
    
37. 
    
38.         case WRITE:
    
39.                 memcpy(sbull_data + (sector << 9), req->buffer, current_nr_sectors << 9);
    
40.                 blk_end_request_cur(req, err);
    
41.                 break;
    
42. 
    
43.         default:
    
44.                 break;
    
45.         }
    
46. }
    
47. 
    
48. static int __init sbull_init(void)
    
49. {
    
50.         int ret;
    
51.         sbull_major = register_blkdev(sbull_major, "sbull");
    
52.         if (sbull_major <= 0) {               
    
53.                 printk(KERN_WARNING "sbull: unable to get major number\n");                                                                                                      
    
54.                 return -EBUSY;
    
55.         }
    
56. 
    
57.         /* I/O scheduler passes ordered requests to device driver through struct request_queue */
    
58.         request = blk_init_queue(sbull_request, NULL);
    
59.         if (!request) {
    
60.                 ret = -ENOMEM;
    
61.                 printk (KERN_NOTICE "blk_init_queue failure\n");
    
62.                 goto err_init_queue;
    
63.         }       
    
64. 
    
65.         gd = alloc_disk(1);
    
66.         if (!gd) {
    
67.                 ret = -ENOMEM;
    
68.                 printk (KERN_NOTICE "alloc_disk failure\n");
    
69.                 goto err_alloc_disk;
    
70.         }
    
71.        
    
72.         strcpy(gd->disk_name, "sbull");
    
73.         gd->major = sbull_major;
    
74.         gd->first_minor = 0;
    
75.         gd->fops = &sbull_fops;
    
76.         gd->queue = request;
    
77.         set_capacity(gd, nsectors*(hardsect_size/KERNEL_SECTOR_SIZE));
    
78.         add_disk(gd);
    
79.        
    
80.         return 0;
    
81. 
    
82. err_alloc_disk:
    
83.         blk_cleanup_queue(request);
    
84. err_init_queue:
    
85.         return ret;
    
86. }
    
87. 
    
88. static void __exit sbull_exit(void)
    
89. {
    
90.         del_gendisk(gd);
    
91.         put_disk(gd);
    
92.         blk_cleanup_queue(request);
    
93. }
    
94. 
    
95. module_init(sbull_init);
    
96. module_exit(sbull_exit);
    

复制代码

c04n05

看到了第3章了。觉得非常不错。
感谢LZ分享

我在fedora 9下面碰到了和193楼类似的问题。。悲剧。
BTW:给大家分享一个基树的资料http://www.360doc.com/content/09/1017/08/313373_7396041.shtml

yanghao

把blk_end_request_cur 换成__blk_end_request_cur