On Wed, 2017-01-04 at 17:41 -0500, Keith Busch wrote:
> +static void blk_mq_abandon_stopped_requests(struct request_queue *q)
> +{
> + int i;
> + struct request *rq, *next;
> + struct blk_mq_hw_ctx *hctx;
> + LIST_HEAD(rq_list);
> +
> + blk_mq_sync_queue(q);
> +
> + spin_lock(&q->requeue_lock);
> + list_for_each_entry_safe(rq, next, &q->requeue_list, queuelist) {
> + struct blk_mq_ctx *ctx;
> +
> + ctx = rq->mq_ctx;
> + hctx = blk_mq_map_queue(q, ctx->cpu);
> + if (blk_mq_hctx_stopped(hctx)) {
> + list_del_init(&rq->queuelist);
> +
> + spin_lock(&hctx->lock);
> + list_add_tail(&rq->queuelist, &rq_list);
> + spin_unlock(&hctx->lock);
> + }
> + }
> +
> + queue_for_each_hw_ctx(q, hctx, i) {
> + if (!blk_mq_hctx_stopped(hctx))
> + continue;
> +
> + flush_busy_ctxs(hctx, &rq_list);
> +
> + spin_lock(&hctx->lock);
> + if (!list_empty(&hctx->dispatch))
> + list_splice_init(&hctx->dispatch, &rq_list);
> + spin_unlock(&hctx->lock);
> + }
> + spin_unlock(&q->requeue_lock);
> +
> + while (!list_empty(&rq_list)) {
> + rq = list_first_entry(&rq_list, struct request, queuelist);
> + list_del_init(&rq->queuelist);
> + rq->errors = -EAGAIN;
> + blk_mq_end_request(rq, rq->errors);
> + }
> +}
Hello Keith,
This patch adds a second code path to the blk-mq core for running queues and
hence will make the blk-mq core harder to maintain. Have you considered to
implement this functionality by introducing a new "fail all requests" flag
for hctx queues such that blk_mq_abandon_stopped_requests() can reuse the
existing mechanism for running a queue?
Bart.
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