Hi Boaz,
On Thu, 08 Nov 2007 19:03:18 +0200, Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
> At the block level bidi request uses req->next_rq pointer for a second
> bidi_read request.
> At Scsi-midlayer a second scsi_data_buffer structure is used for the
> bidi_read part. This bidi scsi_data_buffer is put on
> request->next_rq->special. Struct scsi_cmnd is not changed.
>
> - Define scsi_bidi_cmnd() to return true if it is a bidi request and a
> second sgtable was allocated.
>
> - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer
> from this command This API is to isolate users from the mechanics of
> bidi.
>
> - Define scsi_end_bidi_request() to do what scsi_end_request() does but
> for a bidi request. This is necessary because bidi commands are a bit
> tricky here. (See comments in body)
<snip>
> /*
> + * Bidi commands Must be complete as a whole, both sides at once.
> + * If part of the bytes were written and lld returned
> + * scsi_in()->resid and/or scsi_out()->resid this information will be left
> + * in req->data_len and req->next_rq->data_len. The upper-layer driver can
> + * decide what to do with this information.
> + */
> +void scsi_end_bidi_request(struct scsi_cmnd *cmd)
> +{
> + struct request *req = cmd->request;
> +
> + end_that_request_chunk(req, 1, req->data_len);
> + req->data_len = scsi_out(cmd)->resid;
> +
> + end_that_request_chunk(req->next_rq, 1, req->next_rq->data_len);
> + req->next_rq->data_len = scsi_in(cmd)->resid;
> +
> + scsi_release_buffers(cmd);
> +
> + /*
> + *FIXME: If ll_rw_blk.c is changed to also put_request(req->next_rq)
> + * in end_that_request_last() then this WARN_ON must be removed.
> + * for now, upper-driver must have registered an end_io.
> + */
> + WARN_ON(!req->end_io);
> +
> + scsi_finalize_request(cmd, 1);
> +}
I'm trying to refine the request completion interface between
device drivers and the block-layer.
(http://marc.info/?l=linux-kernel&m=118953696504819&w=2)
For that work, I wish to keep the space between
end_that_request_chunk() and end_that_request_last() simpler
as much as possible so that they can be converted to the interface
easily.
So I'd like to ask you whether 3 reorderings below cause problem
for you.
1. reorder end_that_request_chunk() calls for req and req->next_rq
2. set data_len before end_that_request_chunk() calls
3. call scsi_release_buffer() after scsi_finalize_request()
void scsi_end_bidi_request(struct scsi_cmnd *cmd)
{
struct request *req = cmd->request;
unsigned int dlen = req->data_len;
unsigned int next_dlen = req->next_rq->data_len;
req->data_len = scsi_out(cmd)->resid;
req->next_rq->data_len = scsi_in(cmd)->resid;
end_that_request_chunk(req->next_rq, 1, next_dlen);
end_that_request_chunk(req, 1, dlen);
scsi_finalize_request(cmd, 1);
scsi_release_buffers(cmd);
}
If they are no problem, I could easily convert it to the new interface.
Thanks,
Kiyoshi Ueda
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