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>

1 files changed, 8 insertions, 14 deletions

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 22caf808bfab..7f38ae687b08 100644
--- 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;
 }