Question

Implement a Linux Block Driver which simulates a block device with a region of memory init, exit, and IO functionalities must be included.

Please use either C or C++ Programming for this

Thank You!

Answer 1

#include <linux/genhd.h>
#include <linux/fs.h>
#include <linux/blkdev.h>

#define NR_SECTORS                   1024

#define KERNEL_SECTOR_SIZE           512

static struct my_block_dev {
    //...
    spinlock_t lock;                /* For mutual exclusion */
    struct request_queue *queue;    /* The device request queue */
    struct gendisk *gd;             /* The gendisk structure */
    //...
} dev;

static int create_block_device(struct my_block_dev *dev)
{
    ...
    /* Initialize the gendisk structure */
    dev->gd = alloc_disk(MY_BLOCK_MINORS);
    if (!dev->gd) {
        printk (KERN_NOTICE "alloc_disk failure\n");
        return -ENOMEM;
    }

    dev->gd->major = MY_BLOCK_MAJOR;
    dev->gd->first_minor = 0;
    dev->gd->fops = &my_block_ops;
    dev->gd->queue = dev->queue;
    dev->gd->private_data = dev;
    snprintf (dev->gd->disk_name, 32, "myblock");
    set_capacity(dev->gd, NR_SECTORS);

    add_disk(dev->gd);

    return 0;
}

static int my_block_init(void)
{
    int status;
    //...
    status = create_block_device(&dev);
    if (status < 0)
        return status;
    //...
}

static void delete_block_device(struct my_block_dev *dev)
{
    if (dev->gd) {
        del_gendisk(dev->gd);
    }
    //...
}

static void my_block_exit(void)
{
    delete_block_device(&dev);
    //...
}