mm/balloon_compaction: remove balloon mapping and flag AS_BALLOON_MAP

Now ballooned pages are detected using PageBalloon().  Fake mapping is no
longer required.  This patch links ballooned pages to balloon device using
field page->private instead of page->mapping.  Also this patch embeds
balloon_dev_info directly into struct virtio_balloon.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 47 deletions

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index c3eb93fc9261..2bad7f9dd2ac 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -59,7 +59,7 @@ struct virtio_balloon
          * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE
          * to num_pages above.
          */
-        struct balloon_dev_info *vb_dev_info;
+        struct balloon_dev_info vb_dev_info;
 
         /* Synchronize access/update to this struct virtio_balloon elements */
         struct mutex balloon_lock;
@@ -127,7 +127,7 @@ static void set_page_pfns(u32 pfns[], struct page *page)
 
 static void fill_balloon(struct virtio_balloon *vb, size_t num)
 {
-        struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;
+        struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
 
         /* We can only do one array worth at a time. */
         num = min(num, ARRAY_SIZE(vb->pfns));
@@ -171,7 +171,7 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
 static void leak_balloon(struct virtio_balloon *vb, size_t num)
 {
         struct page *page;
-        struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;
+        struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
 
         /* We can only do one array worth at a time. */
         num = min(num, ARRAY_SIZE(vb->pfns));
@@ -353,12 +353,11 @@ static int init_vqs(struct virtio_balloon *vb)
         return 0;
 }
 
-static const struct address_space_operations virtio_balloon_aops;
 #ifdef CONFIG_BALLOON_COMPACTION
 /*
  * virtballoon_migratepage - perform the balloon page migration on behalf of
  *                           a compation thread.     (called under page lock)
- * @mapping: the page->mapping which will be assigned to the new migrated page.
+ * @vb_dev_info: the balloon device
  * @newpage: page that will replace the isolated page after migration finishes.
  * @page   : the isolated (old) page that is about to be migrated to newpage.
  * @mode   : compaction mode -- not used for balloon page migration.
@@ -373,17 +372,13 @@ static const struct address_space_operations virtio_balloon_aops;
  * This function preforms the balloon page migration task.
  * Called through balloon_mapping->a_ops->migratepage
  */
-static int virtballoon_migratepage(struct address_space *mapping,
+static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
                 struct page *newpage, struct page *page, enum migrate_mode mode)
 {
-        struct balloon_dev_info *vb_dev_info = balloon_page_device(page);
-        struct virtio_balloon *vb;
+        struct virtio_balloon *vb = container_of(vb_dev_info,
+                        struct virtio_balloon, vb_dev_info);
         unsigned long flags;
 
-        BUG_ON(!vb_dev_info);
-
-        vb = vb_dev_info->balloon_device;
-
         /*
          * In order to avoid lock contention while migrating pages concurrently
          * to leak_balloon() or fill_balloon() we just give up the balloon_lock
@@ -399,7 +394,7 @@ static int virtballoon_migratepage(struct address_space *mapping,
 
         /* balloon's page migration 1st step  -- inflate "newpage" */
         spin_lock_irqsave(&vb_dev_info->pages_lock, flags);
-        balloon_page_insert(newpage, mapping, &vb_dev_info->pages);
+        balloon_page_insert(vb_dev_info, newpage);
         vb_dev_info->isolated_pages--;
         spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
         vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
@@ -418,18 +413,11 @@ static int virtballoon_migratepage(struct address_space *mapping,
 
         return MIGRATEPAGE_SUCCESS;
 }
-
-/* define the balloon_mapping->a_ops callback to allow balloon page migration */
-static const struct address_space_operations virtio_balloon_aops = {
-                        .migratepage = virtballoon_migratepage,
-};
 #endif /* CONFIG_BALLOON_COMPACTION */
 
 static int virtballoon_probe(struct virtio_device *vdev)
 {
         struct virtio_balloon *vb;
-        struct address_space *vb_mapping;
-        struct balloon_dev_info *vb_devinfo;
         int err;
 
         vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
@@ -445,30 +433,14 @@ static int virtballoon_probe(struct virtio_device *vdev)
         vb->vdev = vdev;
         vb->need_stats_update = 0;
 
-        vb_devinfo = balloon_devinfo_alloc(vb);
-        if (IS_ERR(vb_devinfo)) {
-                err = PTR_ERR(vb_devinfo);
-                goto out_free_vb;
-        }
-
-        vb_mapping = balloon_mapping_alloc(vb_devinfo,
-                                           (balloon_compaction_check()) ?
-                                           &virtio_balloon_aops : NULL);
-        if (IS_ERR(vb_mapping)) {
-                /*
-                 * IS_ERR(vb_mapping) && PTR_ERR(vb_mapping) == -EOPNOTSUPP
-                 * This means !CONFIG_BALLOON_COMPACTION, otherwise we get off.
-                 */
-                err = PTR_ERR(vb_mapping);
-                if (err != -EOPNOTSUPP)
-                        goto out_free_vb_devinfo;
-        }
-
-        vb->vb_dev_info = vb_devinfo;
+        balloon_devinfo_init(&vb->vb_dev_info);
+#ifdef CONFIG_BALLOON_COMPACTION
+        vb->vb_dev_info.migratepage = virtballoon_migratepage;
+#endif
 
         err = init_vqs(vb);
         if (err)
-                goto out_free_vb_mapping;
+                goto out_free_vb;
 
         vb->thread = kthread_run(balloon, vb, "vballoon");
         if (IS_ERR(vb->thread)) {
@@ -480,10 +452,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
 
 out_del_vqs:
         vdev->config->del_vqs(vdev);
-out_free_vb_mapping:
-        balloon_mapping_free(vb_mapping);
-out_free_vb_devinfo:
-        balloon_devinfo_free(vb_devinfo);
 out_free_vb:
         kfree(vb);
 out:
@@ -509,8 +477,6 @@ static void virtballoon_remove(struct virtio_device *vdev)
 
         kthread_stop(vb->thread);
         remove_common(vb);
-        balloon_mapping_free(vb->vb_dev_info->mapping);
-        balloon_devinfo_free(vb->vb_dev_info);
         kfree(vb);
 }