Messages in this thread | | | Subject | Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued | From | "jianchao.wang" <> | Date | Wed, 13 Sep 2017 09:01:25 +0800 |
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Hi ming
On 09/12/2017 06:23 PM, Ming Lei wrote: >> @@ -1029,14 +1029,20 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list) >> if (list_empty(list)) >> bd.last = true; >> else { >> - struct request *nxt; >> - >> nxt = list_first_entry(list, struct request, queuelist); >> bd.last = !blk_mq_get_driver_tag(nxt, NULL, false); >> } >> >> ret = q->mq_ops->queue_rq(hctx, &bd); >> if (ret == BLK_STS_RESOURCE) { >> + /* >> + * If an I/O scheduler has been configured and we got a >> + * driver tag for the next request already, free it again. >> + */ >> + if (!list_empty(list)) { >> + nxt = list_first_entry(list, struct request, queuelist); >> + blk_mq_put_driver_tag(nxt); >> + } > The following way might be more simple and clean: > > if (nxt) > blk_mq_put_driver_tag(nxt); > > meantime 'nxt' need to be cleared inside the 'if (list_empty(list))' > before .queue_rq().
I had ever thought about that, but to avoid add extra command in the fast path, I made the patch above.
Thanks Jianchao
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