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@xxxxxxxxxxx> 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@xxxxxxx > >> Subject: How to rewrite sbull_request in ldd3 for current kernel? > >> Date: Sat, 19 Mar 2016 21:22:19 +0800 > >> To: kernelnewbies@xxxxxxxxxxxxxxxxx > >> > >> 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@xxxxxxxxxxxxxxxxx > >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > _______________________________________________ > > Kernelnewbies mailing list > > Kernelnewbies@xxxxxxxxxxxxxxxxx > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies -- So many immigrant groups have swept through our town that Brooklyn, like Atlantis, reaches mythological proportions in the mind of the world - RI Safir 1998 http://www.mrbrklyn.com DRM is THEFT - We are the STAKEHOLDERS - RI Safir 2002 http://www.nylxs.com - Leadership Development in Free Software http://www2.mrbrklyn.com/resources - Unpublished Archive http://www.coinhangout.com - coins! http://www.brooklyn-living.com Being so tracked is for FARM ANIMALS and and extermination camps, but incompatible with living as a free human being. -RI Safir 2013 _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
