How to rewrite sbull_request in ldd3 for current kernel?

[张云]

Thanks!
I have another question if it is possible to rewrite the data transfer function avoiding the bio complexity? 

Yun Zhang(张云)

> On Mar 20, 2016, at 8:13 AM, Dongli Zhang <dongli.zhang0129 at hotmail.com> wrote:
> 
> Please refer to https://github.com/21cnbao/training/tree/50506cf04bc5616e0c3f3285dbb006c54deb1c53/kernel/drivers/vmem_disk
> 
> Dongli Zhang (张东立)
> http://finallyjustice.github.io
> 
> 
> ________________________________
>> From: zyunone at 163.com 
>> Subject: How to rewrite sbull_request in ldd3 for current kernel? 
>> Date: Sat, 19 Mar 2016 21:22:19 +0800 
>> To: kernelnewbies at kernelnewbies.org 
>> 
>> Hi, 
>> I am reading the book, Linux Driver Development 3. 
>> In the chapter on block driver of this book, I need some help to 
>> rewriting the sbull_request since the kernel’s block API was changed. 
>> 
>> The sbull_request code: 
>> /* 
>> * The simple form of the request function. 
>> */ 
>> static void sbull_request(request_queue_t *q) 
>> { 
>> struct request *req; 
>> 
>> 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); 
>> } 
>> } 
>> 
>> I have rewritten the code above into: 
>> 
>> /* 
>> * The simple form of the request function. 
>> */ 
>> void blkplay_request(struct request_queue *q) 
>> { 
>> struct request *req; 
>> 
>> while (!blk_queue_stopped(q) && 
>> (req = blk_peek_request(q)) != NULL) { 
>> struct blkplay_dev *dev = req->rq_disk->private_data; 
>> blk_start_request(req); 
>> if (req->cmd_type != REQ_TYPE_FS) { 
>> printk (KERN_NOTICE "Skip non-fs request\n"); 
>> blk_end_request(req, -EIO, 0); 
>> continue; 
>> } 
>> 
>> /* I don’t know how to write the statement below */ 
>> blkplay_transfer(dev, req->sector, req->current_nr_sectors, 
>> req->buffer, rq_data_dir(req)); 
>> 
>> blk_end_request_cur(req, 0); 
>> } 
>> } 
>> 
>> 
>> Is the rewrite proper? 
>> 
>> 
>> 
>> The compiler can’t compile it because the request struct no longer has 
>> 
>> the field of ‘sector’ and ‘current_nr_sectors’. I have read the kernel code 
>> 
>> about the request struct, the kernel code said the __data_len and 
>> __sector field of 
>> request struct is internal so that we shouldn’t access them directly. 
>> 
>> How could I rewrite it ? Thanks. 
>> 
>> _______________________________________________ Kernelnewbies mailing 
>> list Kernelnewbies at kernelnewbies.org 
>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies 
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