Kernel block block

Question

I'm currently trying to implement a simple (wrong?) Simple kernel block driver.

I was inspired mainly from the book "Linux Device Drivers", 3rd Edition , which is not completely updated since it was published in 2005.

In any case, logic still exists, and I learned a lot from it. However, the examples are not very effective, as many things have changed since 2005.

I found the github repository where the examples should be updated to work with the latest kernels, but I think there is something else to update as I cannot adapt the examples to make it work with the 4.9.0 kernel

This is how my module was created:

Upon initialization:

• Register the module as a block device with register_blkdev
• Highlight device data buffer
• Spin Lock Initialization
• Initialize the request queue
• Request Queue Setting
• Select structure gendisk
• Fill in the structure gendisk
• Create a disk using add_disk

Then I implemented the function of processing request events from the request queue and processing read and write events on the block device.

Here is the function: (it was very inspired by LLD-3rd with some changes in line with the current kernel functions)

static void block_mod_request(struct request_queue *queue)
{
    printk(KERN_NOTICE "Entering request function\n");
    struct request *request;

    while(NULL != (request = blk_fetch_request(queue)))
    {
        blk_mod_t *self = request->rq_disk->private_data;
        // Check if request is a filesystem request (i.e. moves block of data)
        if(REQ_TYPE_FS != request->cmd_type)
        {
            // Close request with unsuccessful status
            printk(KERN_WARNING "Skip non-fs request\n");
            __blk_end_request_cur(request, -EIO);
            continue;
        }
        // Treat request
        block_mod_transfer(self, blk_rq_pos(request), blk_rq_cur_sectors(request), request->buffer, rq_data_dir(request));
        // Close request with successful status
        __blk_end_request_cur(request, 0);
    }
    return;
}

However, when compiling, I received the following error:

block_mod.c:82:91: error: ‘struct request’ has no member named ‘buffer’
         block_mod_transfer(self, blk_rq_pos(request), blk_rq_cur_sectors(request), request->buffer, rq_data_dir(request));

After checking the file blkdev.hin the v4.9.0 kernel headers, it seems that the field bufferno longer exists in struct request.
However, I can’t find any information on how everything turned out and how to change the code to make it work.

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Answer 1

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