On 12/5/18 12:44 AM, Jianchao Wang wrote:
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index fe92e52..0dfa269 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1899,32 +1899,23 @@ blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
> void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
> struct list_head *list)
> {
> + blk_qc_t cookie = BLK_QC_T_INVALID;
> +
I'm fine with adding this, but I think we need some sort of check for
that not being a valid cookie. That isn't new, we really should have
already.
> while (!list_empty(list)) {
> - blk_status_t ret;
> struct request *rq = list_first_entry(list, struct request,
> queuelist);
>
> - if (!blk_rq_can_direct_dispatch(rq))
> - break;
> -
> list_del_init(&rq->queuelist);
> - ret = blk_mq_request_issue_directly(rq, list_empty(list));
> - if (ret != BLK_STS_OK) {
> - if (ret == BLK_STS_RESOURCE ||
> - ret == BLK_STS_DEV_RESOURCE) {
> - list_add(&rq->queuelist, list);
> - break;
> - }
> - blk_mq_end_request(rq, ret);
> - }
> + blk_mq_try_issue_directly(hctx, rq, &cookie, false,
> + list_empty(list));
Indent the list_empty() one more tab, should be after the ( if possible.
> - * If we didn't flush the entire list, we could have told
> - * the driver there was more coming, but that turned out to
> - * be a lie.
> + * cookie is set to a valid value only when reqeust is issued successfully.
> + * We only need to care about the last request's result, if it is inserted,
> + * kick the hardware with commit_rqs hook.
reqeust -> request
Also lines are too long, limit to 80 chars please.
And why aren't we just using the list_empty() check like before, and not
having to add the inval cookie value?
> - if (!list_empty(list) && hctx->queue->mq_ops->commit_rqs)
> + if ((cookie == BLK_QC_T_INVALID) && hctx->queue->mq_ops->commit_rqs)
> hctx->queue->mq_ops->commit_rqs(hctx);
Redundant parens around the cookie check.
--
Jens Axboe
