How to rewrite sbull_request in ldd3 for current kernel?

[Ruben Safir]

On Sun, Mar 20, 2016 at 01:58:47PM +0800, 张云 wrote:
> Thanks!
> I have another question if it is possible to rewrite the data transfer function avoiding the bio complexity? 


what is the bio complexity that you are refering to?

> 
> 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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> 
> 
> 
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