On 10/6/19 4:45 AM, Ming Lei wrote:
> If hctx becomes dead, all in-queue IO requests aimed at this hctx have to
> be re-submitted, so cover requests queued in scheduler queue.
> 
> Cc: Bart Van Assche <[email protected]>
> Cc: Hannes Reinecke <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Keith Busch <[email protected]>
> Signed-off-by: Ming Lei <[email protected]>
> ---
>  block/blk-mq.c | 30 +++++++++++++++++++++++++-----
>  1 file changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 0b35fdbd1f17..94fd47cef1bc 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2313,6 +2313,7 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, 
> struct hlist_node *node)
>       enum hctx_type type;
>       bool hctx_dead;
>       struct request *rq;
> +     struct elevator_queue *e;
>  
>       hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
>       ctx = __blk_mq_get_ctx(hctx->queue, cpu);
> @@ -2323,12 +2324,31 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, 
> struct hlist_node *node)
>       hctx_dead = cpumask_first_and(hctx->cpumask, cpu_online_mask) >=
>               nr_cpu_ids;
>  
> -     spin_lock(&ctx->lock);
> -     if (!list_empty(&ctx->rq_lists[type])) {
> -             list_splice_init(&ctx->rq_lists[type], &tmp);
> -             blk_mq_hctx_clear_pending(hctx, ctx);
> +     e = hctx->queue->elevator;
> +     if (!e) {
> +             spin_lock(&ctx->lock);
> +             if (!list_empty(&ctx->rq_lists[type])) {
> +                     list_splice_init(&ctx->rq_lists[type], &tmp);
> +                     blk_mq_hctx_clear_pending(hctx, ctx);
> +             }
> +             spin_unlock(&ctx->lock);
> +     } else if (hctx_dead) {
> +             LIST_HEAD(sched_tmp);
> +
> +             while ((rq = e->type->ops.dispatch_request(hctx))) {
> +                     if (rq->mq_hctx != hctx)
> +                             list_add(&rq->queuelist, &sched_tmp);
> +                     else
> +                             list_add(&rq->queuelist, &tmp);
> +             }
> +
> +             while (!list_empty(&sched_tmp)) {
> +                     rq = list_entry(sched_tmp.next, struct request,
> +                                     queuelist);
> +                     list_del_init(&rq->queuelist);
> +                     blk_mq_sched_insert_request(rq, true, true, true);
> +             }
>       }
> -     spin_unlock(&ctx->lock);
>  
>       if (list_empty(&tmp))
>               return 0;
> 
Reviewed-by: Hannes Reinecke <[email protected]>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                   Teamlead Storage & Networking
[email protected]                                      +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 247165 (AG München), GF: Felix Imendörffer

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