On Mon, Jan 15 2018 at 11:58am -0500,
Ming Lei <ming....@redhat.com> wrote:
> No functional change, just to clean up code a bit, so that the following
> change of using direct issue for blk_mq_request_bypass_insert() which is
> needed by DM can be easier to do.
>
> Signed-off-by: Ming Lei <ming....@redhat.com>
> ---
> block/blk-mq.c | 39 +++++++++++++++++++++++++++------------
> 1 file changed, 27 insertions(+), 12 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index edb1291a42c5..bf8d6651f40e 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1696,15 +1696,37 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx
> *hctx, struct request *rq)
> return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
> }
>
> -static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
> - struct request *rq,
> - blk_qc_t *cookie)
> +static blk_status_t __blk_mq_issue_req(struct blk_mq_hw_ctx *hctx,
> + struct request *rq,
> + blk_qc_t *new_cookie)
> {
> + blk_status_t ret;
> struct request_queue *q = rq->q;
> struct blk_mq_queue_data bd = {
> .rq = rq,
> .last = true,
> };
> +
> + if (!blk_mq_get_driver_tag(rq, NULL, false))
> + return BLK_STS_AGAIN;
> +
> + if (!blk_mq_get_dispatch_budget(hctx)) {
> + blk_mq_put_driver_tag(rq);
> + return BLK_STS_AGAIN;
> + }
> +
> + *new_cookie = request_to_qc_t(hctx, rq);
> +
> + ret = q->mq_ops->queue_rq(hctx, &bd);
> +
> + return ret;
> +}
> +
> +static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
> + struct request *rq,
> + blk_qc_t *cookie)
> +{
> + struct request_queue *q = rq->q;
> blk_qc_t new_cookie;
> blk_status_t ret;
> bool run_queue = true;
> @@ -1718,22 +1740,15 @@ static void __blk_mq_try_issue_directly(struct
> blk_mq_hw_ctx *hctx,
> if (q->elevator)
> goto insert;
>
> - if (!blk_mq_get_driver_tag(rq, NULL, false))
> + ret = __blk_mq_issue_req(hctx, rq, &new_cookie);
> + if (ret == BLK_STS_AGAIN)
> goto insert;
You're (ab)using BLK_STS_AGAIN as a means to an end...
But what if in the future q->mq_ops->queue_rq() returns BLK_STS_AGAIN?
Mike
