とりあえず動作するlinuxのブロックデバイスドライバ

blkdevtest.c

#include<linux/module.h>
#include<linux/kernel.h>
#include<linux/blkdev.h>

//ブロックデバイスを作ってみたくて試行錯誤しながら書いた
//とりあえず動作することを目標にしたので中身はいい加減

#define MODNAME "blkdevtest"

#define CAPACITY_SECTOR 1024

static int blktest_major;
static spinlock_t blktest_lock;
static struct request_queue *blktest_queue;
struct gendisk *blktest_gd;

static void blktest_request(struct request_queue * queue)
{
  struct request *req;
	struct bio_vec *bv;
	struct req_iterator iter;
	while((req = blk_fetch_request(queue)) != NULL){
		if(req->cmd_type != REQ_TYPE_FS){
			printk(KERN_INFO "req->cmd_type != REQ_TYPE_FS\n");
			__blk_end_request_all(req, -1);
			continue;
		}
		
		rq_for_each_segment(bv, req, iter){
			int len = bv->bv_len;
			unsigned char *buf = page_address(bv->bv_page) + bv->bv_offset;
			int i;
			printk(KERN_INFO "addr = %p, len = %d\n", buf, len);
			if(rq_data_dir(req) == WRITE){
				printk(KERN_INFO "WRITE: %s\n", buf);
			}
			else if(rq_data_dir(req) == READ){
				for(i=0;i<blk_rq_cur_sectors(req);i++){
					int sector = iter.bio->bi_sector + i;
					printk(KERN_INFO "READ: sector = %d\n", sector);
					memset(buf + 512 * i, sector, 512);
				}
			}
		}
		printk(KERN_INFO "sector = %d, cur_bytes = %d, cur_sectors = %d\n", (int)blk_rq_pos(req), blk_rq_cur_bytes(req), blk_rq_cur_sectors(req));
		__blk_end_request_all(req, 0);
	}
}

static struct block_device_operations blktest_fops = {
	.owner = THIS_MODULE,
};

static int __init blktest_init(void)
{
	blktest_major = register_blkdev(0, MODNAME);
	printk(KERN_INFO "[blkdevtest]: major = %d\n", blktest_major);
	if(blktest_major <= 0){
		printk(KERN_WARNING "register_blkdev");
		return blktest_major;
	}
	spin_lock_init(&blktest_lock);
	blktest_queue = blk_init_queue(blktest_request, &blktest_lock);
	if(!blktest_queue){
		printk(KERN_WARNING "blk_init_queue");
		unregister_blkdev(blktest_major, MODNAME);
		return -ENOMEM;
	}
	blktest_gd = alloc_disk(4);
	if(!blktest_gd){
		printk(KERN_WARNING "alloc_disk\n");
		blk_cleanup_queue(blktest_queue);
		unregister_blkdev(blktest_major, MODNAME);
		return -ENOMEM;
	}
	sprintf(blktest_gd->disk_name, "%s", MODNAME);
	blktest_gd->queue = blktest_queue;
	blktest_gd->major = blktest_major;
	blktest_gd->first_minor = 0;
	blktest_gd->fops = &blktest_fops;
	set_capacity(blktest_gd, CAPACITY_SECTOR);
	add_disk(blktest_gd);
	printk(KERN_INFO "module loaded\n");

	return 0;
}

static void __exit blktest_exit(void)
{
	del_gendisk(blktest_gd);
	put_disk(blktest_gd);
	blk_cleanup_queue(blktest_queue);
	unregister_blkdev(blktest_major, MODNAME);
	printk(KERN_INFO "module unloaded");
}

module_init(blktest_init)
module_exit(blktest_exit)

MODULE_DESCRIPTION(MODNAME);