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?
I don’t think request’s bio is much complex. I want to rewrite the data transfer function as simple as possible for getting my driver working even without the knowledges of bio, like the sbull_request.
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.
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