deffering work in requst function using workqueue

[mohanlal jangir <mohanlal@xxxxxxxxxxx>]

I have a question regarding following code from LDD v3

while ((req = elv_next_request(q)) != NULL) {
    struct sbull_dev *dev = req->rq_disk->private_data;
    if (! blk_fs_request(req)) {
       printk (KERN_NOTICE "Skip non-fs request\n");
       end_request(req, 0);
       continue;
    }
    sbull_transfer(dev, req->sector,
                req->current_nr_sectors, req->buffer, rq_data_dir(req));
    end_request(req, 1);
}

If the function sbull_transfer may sleep, can I defer it using work queue? 
Can I dequeue the request before processing as shown in following code.

struct dev_data {
  struct sbull_dev *dev;
  struct request *req;
};

void deffered_routine(void *data) {
   struct dev_data *dev_data = data;
   struct request *req = dev_data->req;
   struct sbull_dev *dev = dev_data->dev;
   sbull_transfer(dev, req->sector,
             req->current_nr_sectors, req->buffer, rq_data_dir(req));

   if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) {
       add_disk_randomness(req->rq_disk);
       //blkdev_dequeue_request(req);
       end_that_request_last(req);
   }
   return;
}

/* request function snip */
while ((req = elv_next_request(q)) != NULL) {
   struct work_struct work;
   struct dev_data device_data;
   struct sbull_dev *dev = req->rq_disk->private_data;
   if (! blk_fs_request(req)) {
        printk (KERN_NOTICE "Skip non-fs request\n");
        end_request(req, 0);
       continue;
   }

   device_data->dev = dev; device_data->req = req;
   INIT_WORK(&work, deffered_routine, &device_data);
   schedule_work(&work);
   blkdev_dequeue_request(req);
}




Regards
Mohanlal 


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