162 lines
3.4 KiB
C
Executable File
162 lines
3.4 KiB
C
Executable File
#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/genhd.h>
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#include <linux/blkdev.h>
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#include <linux/hdreg.h>
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#include <linux/vmalloc.h>
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#define VDSK_MINORS 4
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#define VDSK_HEADS 4
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#define VDSK_SECTORS 16
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#define VDSK_CYLINDERS 256
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#define VDSK_SECTOR_SIZE 512
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#define VDSK_SECTOR_TOTAL (VDSK_HEADS * VDSK_SECTORS * VDSK_CYLINDERS)
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#define VDSK_SIZE (VDSK_SECTOR_TOTAL * VDSK_SECTOR_SIZE)
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static int vdsk_major = 0;
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static char vdsk_name[] = "vdsk";
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struct vdsk_dev
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{
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u8 *data;
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int size;
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spinlock_t lock;
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struct gendisk *gd;
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struct request_queue *queue;
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};
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struct vdsk_dev *vdsk = NULL;
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static int vdsk_open(struct block_device *bdev, fmode_t mode)
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{
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return 0;
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}
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static void vdsk_release(struct gendisk *gd, fmode_t mode)
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{
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}
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static int vdsk_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, unsigned long arg)
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{
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return 0;
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}
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static int vdsk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
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{
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geo->cylinders = VDSK_CYLINDERS;
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geo->heads = VDSK_HEADS;
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geo->sectors = VDSK_SECTORS;
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geo->start = 0;
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return 0;
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}
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static void vdsk_make_request(struct request_queue *q, struct bio *bio)
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{
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struct vdsk_dev *vdsk;
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struct bio_vec bvec;
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struct bvec_iter iter;
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unsigned long offset;
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unsigned long nbytes;
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char *buffer;
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vdsk = q->queuedata;
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bio_for_each_segment(bvec, bio, iter) {
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buffer = __bio_kmap_atomic(bio, iter);
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offset = iter.bi_sector * VDSK_SECTOR_SIZE;
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nbytes = bvec.bv_len;
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if ((offset + nbytes) > get_capacity(vdsk->gd) * VDSK_SECTOR_SIZE) {
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bio_endio(bio, -EINVAL);
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return;
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}
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if (bio_data_dir(bio) == WRITE)
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memcpy(vdsk->data + offset, buffer, nbytes);
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else
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memcpy(buffer, vdsk->data + offset, nbytes);
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__bio_kunmap_atomic(bio);
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}
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bio_endio(bio, 0);
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}
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static struct block_device_operations vdsk_fops = {
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.owner = THIS_MODULE,
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.open = vdsk_open,
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.release = vdsk_release,
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.ioctl = vdsk_ioctl,
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.getgeo = vdsk_getgeo,
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};
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static int __init vdsk_init(void)
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{
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vdsk_major = register_blkdev(vdsk_major, vdsk_name);
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if (vdsk_major <= 0)
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return -EBUSY;
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vdsk = kzalloc(sizeof(struct vdsk_dev), GFP_KERNEL);
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if (!vdsk)
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goto unreg_dev;
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vdsk->size = VDSK_SIZE;
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vdsk->data = vmalloc(vdsk->size);
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if (!vdsk->data)
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goto free_dev;
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spin_lock_init(&vdsk->lock);
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vdsk->queue = blk_alloc_queue(GFP_KERNEL);
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if (vdsk->queue == NULL)
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goto free_data;
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blk_queue_make_request(vdsk->queue, vdsk_make_request);
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blk_queue_logical_block_size(vdsk->queue, VDSK_SECTOR_SIZE);
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vdsk->queue->queuedata = vdsk;
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vdsk->gd = alloc_disk(VDSK_MINORS);
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if (!vdsk->gd)
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goto free_queue;
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vdsk->gd->major = vdsk_major;
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vdsk->gd->first_minor = 0;
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vdsk->gd->fops = &vdsk_fops;
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vdsk->gd->queue = vdsk->queue;
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vdsk->gd->private_data = vdsk;
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snprintf(vdsk->gd->disk_name, 32, "vdsk%c", 'a');
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set_capacity(vdsk->gd, VDSK_SECTOR_TOTAL);
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add_disk(vdsk->gd);
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return 0;
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free_queue:
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blk_cleanup_queue(vdsk->queue);
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free_data:
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vfree(vdsk->data);
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free_dev:
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kfree(vdsk);
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unreg_dev:
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unregister_blkdev(vdsk_major, vdsk_name);
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return -ENOMEM;
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}
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static void __exit vdsk_exit(void)
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{
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del_gendisk(vdsk->gd);
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put_disk(vdsk->gd);
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blk_cleanup_queue(vdsk->queue);
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vfree(vdsk->data);
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kfree(vdsk);
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unregister_blkdev(vdsk_major, vdsk_name);
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}
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module_init(vdsk_init);
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module_exit(vdsk_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Kevin Jiang <jiangxg@farsight.com.cn>");
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MODULE_DESCRIPTION("This is an example for Linux block device driver");
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