Linux 块设备驱动 (1)

链接：http://m.blog.csdn.net/article/details?id=51585490

刚接触一下,发现作者的代码写错了,改一点点,总之受益匪浅

#include <linux/module.h>#include <linux/version.h>#include <linux/fs.h>#include <linux/slab.h>#include <linux/vmalloc.h>#include <linux/blkdev.h>static int sampleblk_major;#define SAMPLEBLK_MINOR1static int sampleblk_sect_size = 512;static int sampleblk_nsects = 10 * 1024;struct sampleblk_dev {int minor;spinlock_t lock;struct request_queue *queue;struct gendisk *disk;ssize_t size;void *data;};struct sampleblk_dev *sampleblk_dev = NULL;/* *  * Do an I/O operation for each segment *   */static int sampleblk_handle_io(struct sampleblk_dev *sampleblk_dev,uint64_t pos, ssize_t size, void *buffer, int write){if (write)memcpy(sampleblk_dev->data + pos, buffer, size);elsememcpy(buffer, sampleblk_dev->data + pos, size);return 0;}static void sampleblk_request(struct request_queue *q){struct request *rq = NULL;int rv = 0;uint64_t pos = 0;ssize_t size = 0;struct bio_vec* bvec;struct req_iterator iter;void *kaddr = NULL;while ((rq = blk_fetch_request(q)) != NULL) {spin_unlock_irq(q->queue_lock);if (rq->cmd_type != REQ_TYPE_FS) {rv = -EIO;goto skip;}BUG_ON(sampleblk_dev != rq->rq_disk->private_data);pos = blk_rq_pos(rq) * sampleblk_sect_size;size = blk_rq_bytes(rq);if ((pos + size > sampleblk_dev->size)) {pr_crit("sampleblk: Beyond-end write (%llu %zx)\n",pos, size);rv = -EIO;goto skip;}rq_for_each_segment(bvec, rq, iter) {kaddr = kmap(bvec->bv_page);rv = sampleblk_handle_io(sampleblk_dev, pos,bvec->bv_len, kaddr + bvec->bv_offset,rq_data_dir(rq));if (rv < 0)goto skip;pos += bvec->bv_len;kunmap(bvec->bv_page);}skip:blk_end_request_all(rq, rv);spin_lock_irq(q->queue_lock);}}static int sampleblk_ioctl(struct block_device *bdev, fmode_t mode,unsigned command, unsigned long argument){return 0;}static int sampleblk_open(struct block_device *bdev, fmode_t mode){return 0;}static void sampleblk_release(struct gendisk *disk, fmode_t mode){}static const struct block_device_operations sampleblk_fops = {.owner = THIS_MODULE,.open = sampleblk_open,.release = sampleblk_release,.ioctl = sampleblk_ioctl,};static int sampleblk_alloc(int minor){struct gendisk *disk;int rv = 0;sampleblk_dev = kzalloc(sizeof(struct sampleblk_dev), GFP_KERNEL);if (!sampleblk_dev) {rv = -ENOMEM;goto fail;}sampleblk_dev->size = sampleblk_sect_size * sampleblk_nsects;sampleblk_dev->data = vmalloc(sampleblk_dev->size);if (!sampleblk_dev->data) {rv = -ENOMEM;goto fail_dev;}sampleblk_dev->minor = minor;spin_lock_init(&sampleblk_dev->lock);sampleblk_dev->queue = blk_init_queue(sampleblk_request,    &sampleblk_dev->lock);if (!sampleblk_dev->queue) {rv = -ENOMEM;goto fail_data;}disk = alloc_disk(minor);if (!disk) {rv = -ENOMEM;goto fail_queue;}sampleblk_dev->disk = disk;disk->major = sampleblk_major;disk->first_minor = minor;disk->fops = &sampleblk_fops;disk->private_data = sampleblk_dev;disk->queue = sampleblk_dev->queue;sprintf(disk->disk_name, "sampleblk%d", minor);set_capacity(disk, sampleblk_nsects);add_disk(disk);return 0;fail_queue:blk_cleanup_queue(sampleblk_dev->queue);fail_data:vfree(sampleblk_dev->data);fail_dev:kfree(sampleblk_dev);fail:return rv;}static void sampleblk_free(struct sampleblk_dev *sampleblk_dev){del_gendisk(sampleblk_dev->disk);blk_cleanup_queue(sampleblk_dev->queue);put_disk(sampleblk_dev->disk);vfree(sampleblk_dev->data);kfree(sampleblk_dev);}static int __init sampleblk_init(void){int rv = 0;sampleblk_major = register_blkdev(0, "sampleblk");if (sampleblk_major < 0)return sampleblk_major;rv = sampleblk_alloc(SAMPLEBLK_MINOR);if (rv < 0)pr_info("sampleblk: disk allocation failed with %d\n", rv);pr_info("sampleblk: module loaded\n");return 0;}static void __exit sampleblk_exit(void){sampleblk_free(sampleblk_dev);unregister_blkdev(sampleblk_major, "sampleblk");pr_info("sampleblk: module unloaded\n");}module_init(sampleblk_init);module_exit(sampleblk_exit);MODULE_LICENSE("GPL");