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| #include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/genhd.h>
#include <linux/hdreg.h>
#include <linux/vmalloc.h>
#include <linux/bio.h>
#define RAMDISK_SECTOR_SIZE 512
#define RAMDISK_SIZE (1024 * 1024 * 10) // 10MB
static int major_num = 0;
static struct request_queue *queue;
static struct gendisk *disk;
static unsigned char *ramdisk_data;
#if 0
static void
ramdisk_transfer(struct request *req)
{
struct bio_vec bvec;
struct req_iterator iter;
sector_t pos = blk_rq_pos(req);
unsigned int num_sectors = blk_rq_sectors(req);
unsigned int offset = pos * RAMDISK_SECTOR_SIZE;
///< unsigned int nbytes = num_sectors * RAMDISK_SECTOR_SIZE;
rq_for_each_segment(bvec, req, iter)
{
void *buffer = page_address(bvec.bv_page) + bvec.bv_offset;
if (rq_data_dir(req) == READ)
{
memcpy(buffer, ramdisk_data + offset, bvec.bv_len);
}
else
{
memcpy(ramdisk_data + offset, buffer, bvec.bv_len);
}
offset += bvec.bv_len;
}
}
#endif
static blk_qc_t
ramdisk_make_request(struct request_queue *q, struct bio *bio)
{
bio_endio(bio);
return BLK_QC_T_NONE;
}
static int
ramdisk_open(struct block_device *bdev, fmode_t mode)
{
printk("open ramdisk ...");
return 0;
}
static void
ramdisk_release(struct gendisk *gd, fmode_t mode)
{
printk("close ramdisk ...");
}
static struct block_device_operations fops =
{
.owner = THIS_MODULE,
.open = ramdisk_open,
.release = ramdisk_release,
};
static int __init ramdisk_init(void)
{
ramdisk_data = vmalloc(RAMDISK_SIZE);
if (!ramdisk_data)
{
return -ENOMEM;
}
major_num = register_blkdev(0, "ramdisk");
if (major_num <= 0)
{
vfree(ramdisk_data);
return -EBUSY;
}
queue = blk_alloc_queue(GFP_KERNEL);
if (!queue)
{
unregister_blkdev(major_num, "ramdisk");
vfree(ramdisk_data);
return -ENOMEM;
}
blk_queue_make_request(queue, ramdisk_make_request);
disk = alloc_disk(1);
if (!disk)
{
blk_cleanup_queue(queue);
unregister_blkdev(major_num, "ramdisk");
vfree(ramdisk_data);
return -ENOMEM;
}
strcpy(disk->disk_name, "ramdisk0");
disk->major = major_num;
disk->first_minor = 0;
disk->fops = &fops;
disk->queue = queue;
set_capacity(disk, RAMDISK_SIZE / RAMDISK_SECTOR_SIZE);
add_disk(disk);
return 0;
}
static void __exit ramdisk_exit(void)
{
del_gendisk(disk);
put_disk(disk);
blk_cleanup_queue(queue);
unregister_blkdev(major_num, "ramdisk");
vfree(ramdisk_data);
}
module_init(ramdisk_init);
module_exit(ramdisk_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("lpyuan");
MODULE_DESCRIPTION("RAM Disk Block Device Driver");
|
