Re: [RFC] FC pass thru - Rev IV

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Thu, 2008-11-27 at 18:53 +0900, FUJITA Tomonori wrote:
> > +	blk_end_bidi_request(job->req, err, blk_rq_bytes(job->req), bytes_requested);
> > 
> > The residual count is left in req->data_len. Does bsg have a way to return the
> > residual to user-mode? It must, since Pete was using that for sure. Note that
> > you are looking for the bidi_read residual count.
> 
> Yeah, bsg has. struct sg_io_v4 has:
> 
> __s32 din_resid;	/* [o] din_xfer_len - actual_din_xfer_len */
> __s32 dout_resid;	/* [o] dout_xfer_len - actual_dout_xfer_len */
> 
> 
> > As was said by people. You must complete ALL bytes on both sides. Residual information
> > is passed through req->data_len. Other wise the request is still active.
> > 
> > (And yes blk_end_request uses blk_end_bidi_request internally)
> 
> We always complete all bytes on both sides. So why we do something
> like:
> 
> int blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
> {
> 	unsigned int bidi_bytes	= 0;
> 
> 	if (blk_bidi_rq(rq))
> 		bidi_bytes = req->next_rq->data_len;
> 
> 	return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL);
> }

That looks good ... care to patch it up (including conversion of all the
users) and send it to Jens for consideration?

> The callers can do something like:
> 
> blk_end_request(rq, err, rq->data_len);
> rq-->next_rq->data_len = resid;

Um ... I see what you're trying to do, but I don't think it works like
this.  The residual could be collected in the end_io call back which is
inline in the blk_end_request().

James