Like bdrv_next()  - bdrv_next_dirty_bitmap() is a function to provide
access to private dirty bitmaps list.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c         | 10 ++++++++++
 include/block/dirty-bitmap.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 519737c..7547c78 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -533,3 +533,13 @@ int64_t bdrv_get_meta_dirty_count(BdrvDirtyBitmap *bitmap)
 {
     return hbitmap_count(bitmap->meta);
 }
+
+BdrvDirtyBitmap *bdrv_next_dirty_bitmap(BlockDriverState *bs,
+                                        BdrvDirtyBitmap *bitmap)
+{
+    if (bitmap == NULL) {
+        return QLIST_FIRST(&bs->dirty_bitmaps);
+    }
+
+    return QLIST_NEXT(bitmap, list);
+}
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index 9dea14b..1a457d5 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -72,4 +72,7 @@ void bdrv_dirty_bitmap_deserialize_zeroes(BdrvDirtyBitmap *bitmap,
                                           bool finish);
 void bdrv_dirty_bitmap_deserialize_finish(BdrvDirtyBitmap *bitmap);
 
+BdrvDirtyBitmap *bdrv_next_dirty_bitmap(BlockDriverState *bs,
+                                        BdrvDirtyBitmap *bitmap);
+
 #endif
-- 
1.8.3.1