diff --git a/block.c b/block.c
index fb9341c..00fe345 100644
--- a/block.c
+++ b/block.c
@@ -44,6 +44,7 @@
 #include <windows.h>
 #endif
 
+static void bdrv_dev_change_cb(BlockDriverState *bs, int reason);
 static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
         BlockDriverCompletionFunc *cb, void *opaque);
@@ -688,10 +689,8 @@
     }
 
     if (!bdrv_key_required(bs)) {
-        /* call the change callback */
         bs->media_changed = 1;
-        if (bs->change_cb)
-            bs->change_cb(bs->change_opaque, CHANGE_MEDIA);
+        bdrv_dev_change_cb(bs, CHANGE_MEDIA);
     }
 
     return 0;
@@ -727,10 +726,8 @@
             bdrv_close(bs->file);
         }
 
-        /* call the change callback */
         bs->media_changed = 1;
-        if (bs->change_cb)
-            bs->change_cb(bs->change_opaque, CHANGE_MEDIA);
+        bdrv_dev_change_cb(bs, CHANGE_MEDIA);
     }
 }
 
@@ -792,8 +789,8 @@
 {
     assert(bs->dev == dev);
     bs->dev = NULL;
-    bs->change_cb = NULL;
-    bs->change_opaque = NULL;
+    bs->dev_ops = NULL;
+    bs->dev_opaque = NULL;
 }
 
 /* TODO change to return DeviceState * when all users are qdevified */
@@ -802,6 +799,20 @@
     return bs->dev;
 }
 
+void bdrv_set_dev_ops(BlockDriverState *bs, const BlockDevOps *ops,
+                      void *opaque)
+{
+    bs->dev_ops = ops;
+    bs->dev_opaque = opaque;
+}
+
+static void bdrv_dev_change_cb(BlockDriverState *bs, int reason)
+{
+    if (bs->dev_ops && bs->dev_ops->change_cb) {
+        bs->dev_ops->change_cb(bs->dev_opaque, reason);
+    }
+}
+
 /*
  * Run consistency checks on an image
  *
@@ -1272,9 +1283,7 @@
     ret = drv->bdrv_truncate(bs, offset);
     if (ret == 0) {
         ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
-        if (bs->change_cb) {
-            bs->change_cb(bs->change_opaque, CHANGE_SIZE);
-        }
+        bdrv_dev_change_cb(bs, CHANGE_SIZE);
     }
     return ret;
 }
@@ -1612,15 +1621,6 @@
     return bs->enable_write_cache;
 }
 
-/* XXX: no longer used */
-void bdrv_set_change_cb(BlockDriverState *bs,
-                        void (*change_cb)(void *opaque, int reason),
-                        void *opaque)
-{
-    bs->change_cb = change_cb;
-    bs->change_opaque = opaque;
-}
-
 int bdrv_is_encrypted(BlockDriverState *bs)
 {
     if (bs->backing_hd && bs->backing_hd->encrypted)
@@ -1659,8 +1659,7 @@
         bs->valid_key = 1;
         /* call the change callback now, we skipped it on open */
         bs->media_changed = 1;
-        if (bs->change_cb)
-            bs->change_cb(bs->change_opaque, CHANGE_MEDIA);
+        bdrv_dev_change_cb(bs, CHANGE_MEDIA);
     }
     return ret;
 }