virtio-balloon: deflate via a page list

This patch saves the deflated pages to a list, instead of the PFN array.
Accordingly, the balloon_pfn_to_page() function is removed.

Signed-off-by: Liang Li <liang.z.li@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 22caf808bfaba97e45662de0f4150632bcb85d2f..7f38ae687b0866fcc47fb4602e5cc341711cc077 100644 (file)
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -104,12 +104,6 @@ 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;
@@ -182,18 +176,16 @@ 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 */
        }
 }
@@ -203,6 +195,7 @@ 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));
@@ -216,6 +209,7 @@ 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;
        }
 
@@ -227,7 +221,7 @@ 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;
 }