On Mon, Nov 26, 2018 at 09:35:55AM -0700, Jens Axboe wrote:
> If we are issuing a list of requests, we know if we're at the last one.
> If we fail issuing, ensure that we call ->commits_rqs() to flush any
> potential previous requests.
>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
> ---
> block/blk-core.c | 2 +-
> block/blk-mq.c | 32 ++++++++++++++++++++++++--------
> block/blk-mq.h | 2 +-
> 3 files changed, 26 insertions(+), 10 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index c9758d185357..808a65d23f1a 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1334,7 +1334,7 @@ blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *
> * bypass a potential scheduler on the bottom device for
> * insert.
> */
> - return blk_mq_request_issue_directly(rq);
> + return blk_mq_request_issue_directly(rq, true);
> }
> EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 6a249bf6ed00..0a12cec0b426 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1260,6 +1260,14 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
> if (!list_empty(list)) {
> bool needs_restart;
>
> + /*
> + * 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.
> + */
> + if (q->mq_ops->commit_rqs)
> + q->mq_ops->commit_rqs(hctx);
> +
Looks you miss to do it for blk_mq_do_dispatch_sched() and
blk_mq_do_dispatch_ctx(), in which only one request is added to
the rq_list.
Maybe we can call the .commit_rqs(hctx) just at the end of
blk_mq_sched_dispatch_requests() for cover all non-direct-issue
cases.
Thanks,
Ming
