On 30/05/19 17:36, Bart Van Assche wrote:
> On 5/30/19 4:28 AM, Paolo Bonzini wrote:
>> +static const struct blk_mq_ops scsi_mq_ops_no_commit = {
>> + .get_budget = scsi_mq_get_budget,
>> + .put_budget = scsi_mq_put_budget,
>> + .queue_rq = scsi_queue_rq,
>> + .complete = scsi_softirq_done,
>> + .timeout = scsi_timeout,
>> +#ifdef CONFIG_BLK_DEBUG_FS
>> + .show_rq = scsi_show_rq,
>> +#endif
>> + .init_request = scsi_mq_init_request,
>> + .exit_request = scsi_mq_exit_request,
>> + .initialize_rq_fn = scsi_initialize_rq,
>> + .busy = scsi_mq_lld_busy,
>> + .map_queues = scsi_map_queues,
>> +};
>> +
>> +static void scsi_commit_rqs(struct blk_mq_hw_ctx *hctx)
>> +{
>> + struct request_queue *q = hctx->queue;
>> + struct scsi_device *sdev = q->queuedata;
>> + struct Scsi_Host *shost = sdev->host;
>> +
>> + shost->hostt->commit_rqs(shost, hctx->queue_num);
>> +}
>> +
>> static const struct blk_mq_ops scsi_mq_ops = {
>> .get_budget = scsi_mq_get_budget,
>> .put_budget = scsi_mq_put_budget,
>> .queue_rq = scsi_queue_rq,
>> + .commit_rqs = scsi_commit_rqs,
>> .complete = scsi_softirq_done,
>> .timeout = scsi_timeout,
>> #ifdef CONFIG_BLK_DEBUG_FS
>
> Hi Paolo,
>
> Have you considered to modify the block layer such that a single
> scsi_mq_ops structure can be used for all SCSI LLD types?
Yes, but I don't think it's possible to do it in a nice way.
Any adjustment we make to the block layer to fit the SCSI subsystem's
desires would make all other block drivers uglier, so I chose to confine
the ugliness here.
The root issue is that the SCSI subsystem is unique in how it sits on
top of the block layer; this is the famous "adapter" (or "midlayer",
though that is confusing when talking about SCSI) design that Linux
usually tries to avoid.
Paolo
