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SubjectRe: [Regression x2, 3.13-git] virtio block mq hang, iostat busted on virtio devices
> Just stumbled on that too. You need one more, btw, for the sg failure
> case:
>
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 588479d58f52..6a680d4de7f1 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -199,15 +199,16 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
>
> spin_lock_irqsave(&vblk->vq_lock, flags);
> if (__virtblk_add_req(vblk->vq, vbr, vbr->sg, num) < 0) {
> + virtqueue_kick(vblk->vq);
> spin_unlock_irqrestore(&vblk->vq_lock, flags);
> blk_mq_stop_hw_queue(hctx);
> - virtqueue_kick(vblk->vq);
> return BLK_MQ_RQ_QUEUE_BUSY;
> }
> - spin_unlock_irqrestore(&vblk->vq_lock, flags);
>
> if (last)
> virtqueue_kick(vblk->vq);
> +
> + spin_unlock_irqrestore(&vblk->vq_lock, flags);

Note that virtqueue_kick can be split into a virtqueue_prepare_split
that needs the lock, and a virtqueue_notify that doesn't, but it might
not be nessecary to do that optimization right now.

Btw, how much do I need to bribe you to send mails where I don't have
step over 500 lines of dead quotes to find the actual patch?



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