【Tiny6410 And Linux】—（5.2）—RamDisk 驱动实现（自己绑定 make_request_fn() ）——代码

直接来吧！

 

1、驱动程序

 

①、blk.c

#include <linux/module.h>#include <linux/moduleparam.h>#include <linux/init.h>#include <linux/sched.h>#include <linux/kernel.h>/* printk() */#include <linux/slab.h>/* kmalloc() */#include <linux/fs.h>/* everything... */#include <linux/errno.h>/* error codes */#include <linux/timer.h>#include <linux/types.h>/* size_t */#include <linux/fcntl.h>/* O_ACCMODE */#include <linux/hdreg.h>/* HDIO_GETGEO */#include <linux/kdev_t.h>#include <linux/vmalloc.h>#include <linux/genhd.h>#include <linux/blkdev.h>#include <linux/buffer_head.h>/* invalidate_bdev */#include <linux/bio.h>#include <linux/major.h>#include <linux/version.h>#define SIMP_BLKDEV_DEVICEMAJORCOMPAQ_SMART2_MAJOR#define SIMP_BLKDEV_DISKNAME        "_Justin"#define SIMP_BLKDEV_BYTES        (16 * 1024 * 1024)static struct request_queue *simp_blkdev_queue;static struct gendisk *simp_blkdev_disk;unsigned char simp_blkdev_data[SIMP_BLKDEV_BYTES];/* * simp_blkdev_make_request */static int simp_blkdev_make_request(struct request_queue *q, struct bio *bio){        struct bio_vec *bvec;        int i;        void *dsk_mem;/* 判断 IO 请求是否超出实际 RanDisk 大小 */        if((bio->bi_sector << 9) + bio->bi_size > SIMP_BLKDEV_BYTES) {                printk(KERN_ERR SIMP_BLKDEV_DISKNAME                        ": bad request: block=%llu, count=%u\n",                        (unsigned long long)bio->bi_sector, bio->bi_size);/* 条件编译，对于 2.4 内核之后的变量多了一个，伤不起阿！ */#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 24)                /* 返回这个对 bio 请求的处理结果，－EIO 表示出错 */                bio_endio(bio, 0, -EIO);#else                bio_endio(bio, -EIO);#endif                return 0;        }        dsk_mem = simp_blkdev_data + (bio->bi_sector << 9);        /* 遍历 bio 中所有的 bvec */        bio_for_each_segment(bvec, bio, i)        {                void *iovec_mem;                switch(bio_rw(bio))                {                        case READ:                        case READA:             /* 读和预读都进行同样的处理 */                                /* 用 kmalloc 将请求页映射到非线性映射区域进行                                 * 访问，这种方法主要是为了兼容高端内存，                                 * (bvec->bv_page 可能源于高端内存） */                                iovec_mem = kmap(bvec->bv_page) + bvec->bv_offset;                                memcpy(iovec_mem, dsk_mem, bvec->bv_len);                                kunmap(bvec->bv_page);                                break;                        case WRITE:                                iovec_mem = kmap(bvec->bv_page) + bvec->bv_offset;                                memcpy(dsk_mem, iovec_mem, bvec->bv_len);                                kunmap(bvec->bv_page);                                break;                        default:                                printk(KERN_ERR SIMP_BLKDEV_DISKNAME                                        ":Unknown value of bio_rw: %lu\n",                                        bio_rw(bio));#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 24)                                bio_endio(bio, 0, -EIO);#else                                bio_endio(bio, -EIO);#endif                                return 0;                }                dsk_mem += bvec->bv_len;        }/* 返回这个对 bio 请求的处理结果，0 表示正常 */#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 24)        bio_endio(bio, 0, 0);#else        bio_endio(bio, 0);#endif        return 0;}/*  * block_device_operations */struct block_device_operations simp_blkdev_fops = {        .owner = THIS_MODULE,};/*  * simp_blkdev_init */static int __init simp_blkdev_init(void){        int ret;/* 分配一个请求队列 */        simp_blkdev_queue = blk_alloc_queue(GFP_KERNEL);        if(!simp_blkdev_queue) {                ret = -ENOMEM;                goto err_alloc_queue;        }/* 为请求队列绑定 make_request_fn 方法 */        blk_queue_make_request(simp_blkdev_queue, simp_blkdev_make_request);/* 分配一个 gendisk 结构 */        simp_blkdev_disk = alloc_disk(1);        if(!simp_blkdev_disk) {                ret = -ENOMEM;                goto err_alloc_disk;        }/* 填充 gendisk 主要结构成员 */        strcpy(simp_blkdev_disk->disk_name, SIMP_BLKDEV_DISKNAME);        simp_blkdev_disk->major = SIMP_BLKDEV_DEVICEMAJOR;        simp_blkdev_disk->first_minor = 0;        simp_blkdev_disk->fops = &simp_blkdev_fops;        simp_blkdev_disk->queue = simp_blkdev_queue;        set_capacity(simp_blkdev_disk, SIMP_BLKDEV_BYTES >> 9);/* 向内核注册块设备驱动 */        add_disk(simp_blkdev_disk);        return 0;err_alloc_disk:        blk_cleanup_queue(simp_blkdev_queue);err_alloc_queue:        return ret;}/*  * simp_blkdev_exit */static void __exit simp_blkdev_exit(void){        del_gendisk(simp_blkdev_disk);/* 删除 gendisk 结构 */        put_disk(simp_blkdev_disk);/* 释放一个该对象的引用 */        blk_cleanup_queue(simp_blkdev_queue);/* 清理请求队列 */}module_init(simp_blkdev_init);module_exit(simp_blkdev_exit);

 

②、Makefile

ifneq ($(KERNELRELEASE),)obj-m := blk.oelseKDIR := /lib/modules/2.6.27.62/buildall:make -C $(KDIR) M=$(PWD) modules clean:rm -f *.ko *.o *.mod.o *.mod.c *.symvers  modul*endif

 

2、实验结果