RE: [PATCH 1/6] virtio-balloon: rework deflate to add page to a list

["Li, Liang Z" <liang.z.li@intel.com>]

Hi Michael,

Could you help to review this patch set and give some comments when you have time? 
My work is blocked here.

Thanks !
Liang


> -----Original Message-----
> From: Li, Liang Z
> Sent: Monday, June 13, 2016 5:47 PM
> To: kvm@vger.kernel.org
> Cc: virtio-dev@lists.oasis-open.org; qemu-devel@nongun.org; linux-
> kernel@vger.kernel.org; mst@redhat.com; Li, Liang Z; Paolo Bonzini; Cornelia
> Huck; Amit Shah
> Subject: [PATCH 1/6] virtio-balloon: rework deflate to add page to a list
> 
> will allow faster notifications using a bitmap down the road.
> Now balloon_pfn_to_page() can be removed because it is not used.
> 
> Signed-off-by: Liang Li <liang.z.li@intel.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Amit Shah <amit.shah@redhat.com>
> ---
>  drivers/virtio/virtio_balloon.c | 22 ++++++++--------------
>  1 file changed, 8 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 476c0e3..8d649a2 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -98,12 +98,6 @@ static u32 page_to_balloon_pfn(struct page *page)
>  	return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE;  }
> 
> -static struct page *balloon_pfn_to_page(u32 pfn) -{
> -	BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE);
> -	return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE);
> -}
> -
>  static void balloon_ack(struct virtqueue *vq)  {
>  	struct virtio_balloon *vb = vq->vdev->priv; @@ -176,18 +170,16 @@
> static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
>  	return num_allocated_pages;
>  }
> 
> -static void release_pages_balloon(struct virtio_balloon *vb)
> +static void release_pages_balloon(struct virtio_balloon *vb,
> +				 struct list_head *pages)
>  {
> -	unsigned int i;
> -	struct page *page;
> +	struct page *page, *next;
> 
> -	/* Find pfns pointing at start of each page, get pages and free them.
> */
> -	for (i = 0; i < vb->num_pfns; i +=
> VIRTIO_BALLOON_PAGES_PER_PAGE) {
> -		page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev,
> -							   vb->pfns[i]));
> +	list_for_each_entry_safe(page, next, pages, lru) {
>  		if (!virtio_has_feature(vb->vdev,
> 
> 	VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
>  			adjust_managed_page_count(page, 1);
> +		list_del(&page->lru);
>  		put_page(page); /* balloon reference */
>  	}
>  }
> @@ -197,6 +189,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb,
> size_t num)
>  	unsigned num_freed_pages;
>  	struct page *page;
>  	struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
> +	LIST_HEAD(pages);
> 
>  	/* We can only do one array worth at a time. */
>  	num = min(num, ARRAY_SIZE(vb->pfns));
> @@ -208,6 +201,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb,
> size_t num)
>  		if (!page)
>  			break;
>  		set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
> +		list_add(&page->lru, &pages);
>  		vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
>  	}
> 
> @@ -219,7 +213,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb,
> size_t num)
>  	 */
>  	if (vb->num_pfns != 0)
>  		tell_host(vb, vb->deflate_vq);
> -	release_pages_balloon(vb);
> +	release_pages_balloon(vb, &pages);
>  	mutex_unlock(&vb->balloon_lock);
>  	return num_freed_pages;
>  }
> --
> 1.9.1