On Wed, Dec 12, 2018 at 10:38:13PM -0800, Sagi Grimberg wrote:
> Used forsynchronous requests that needs polling. If we are knowingly
> sending a request down to a poll queue, we need a synchronous interface
> to poll for its completion.
>
> Signed-off-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
> ---
> block/blk-exec.c | 29 +++++++++++++++++++++++++++++
> block/blk-mq.c | 8 --------
> include/linux/blk-mq.h | 8 ++++++++
> include/linux/blkdev.h | 2 ++
> 4 files changed, 39 insertions(+), 8 deletions(-)
>
> diff --git a/block/blk-exec.c b/block/blk-exec.c
> index a34b7d918742..572032d60001 100644
> --- a/block/blk-exec.c
> +++ b/block/blk-exec.c
> @@ -90,3 +90,32 @@ void blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
> wait_for_completion_io(&wait);
> }
> EXPORT_SYMBOL(blk_execute_rq);
> +
> +/**
> + * blk_execute_rq_polled - execute a request and poll for its completion
> + * @q: queue to insert the request in
> + * @bd_disk: matching gendisk
> + * @rq: request to insert
> + * @at_head: insert request at head or tail of queue
> + *
> + * Description:
> + * Insert a fully prepared request at the back of the I/O scheduler queue
> + * for execution and wait for completion.
> + */
> +void blk_execute_rq_polled(struct request_queue *q, struct gendisk *bd_disk,
> + struct request *rq, int at_head)
> +{
> + DECLARE_COMPLETION_ONSTACK(wait);
> +
> + WARN_ON_ONCE(!test_bit(QUEUE_FLAG_POLL, &q->queue_flags));
> +
> + rq->cmd_flags |= REQ_HIPRI;
> + rq->end_io_data = &wait;
> + blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
> +
> + while (!completion_done(&wait)) {
> + blk_poll(q, request_to_qc_t(rq->mq_hctx, rq), true);
> + cond_resched();
> + }
Can we just open code this in nvme for now?
> +static inline blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
Too long line.
> +{
> + if (rq->tag != -1)
> + return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
> +
> + return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
> +}
Also these are only two users of blk_tag_to_qc_t, it might be worth
to fold it into request_to_qc_t:
static inline blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
if (rq->tag != -1)
return rq->tag | (hctx->queue_num << BLK_QC_T_SHIFT);
return rq->internal_tag | (hctx->queue_num << BLK_QC_T_SHIFT) |
BLK_QC_T_INTERNAL;
}
