diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 3010adb909bf17b702428fe84eeb40e851da1045..6e93ec43e117e661c067f4a97df5a9f39c119624 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1004,7 +1004,8 @@ fail:
     return false;
 }
 
-int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)
+int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,
+                                 Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
     Qcow2BitmapList *bm_list;
@@ -1012,6 +1013,10 @@ int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)
     GSList *ro_dirty_bitmaps = NULL;
     int ret = 0;
 
+    if (header_updated != NULL) {
+        *header_updated = false;
+    }
+
     if (s->nb_bitmaps == 0) {
         /* No bitmaps - nothing to do */
         return 0;
@@ -1055,6 +1060,9 @@ int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)
             error_setg_errno(errp, -ret, "Can't update bitmap directory");
             goto out;
         }
+        if (header_updated != NULL) {
+            *header_updated = true;
+        }
         g_slist_foreach(ro_dirty_bitmaps, set_readonly_helper, false);
     }
 
@@ -1065,6 +1073,11 @@ out:
     return ret;
 }
 
+int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)
+{
+    return qcow2_reopen_bitmaps_rw_hint(bs, NULL, errp);
+}
+
 /* store_bitmap_data()
  * Store bitmap to image, filling bitmap table accordingly.
  */
diff --git a/block/qcow2.c b/block/qcow2.c
index cf4f3becae636fdaa266e70567a73be7167b7d7c..486f3e83b779c99099d307365aa41152ea99daa8 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1480,7 +1480,22 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
         s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
     }
 
-    if (qcow2_load_dirty_bitmaps(bs, &local_err)) {
+    if (bdrv_dirty_bitmap_next(bs, NULL)) {
+        /* It's some kind of reopen with already existing dirty bitmaps. There
+         * are no known cases where we need loading bitmaps in such situation,
+         * so it's safer don't load them.
+         *
+         * Moreover, if we have some readonly bitmaps and we are reopening for
+         * rw we should reopen bitmaps correspondingly.
+         */
+        if (bdrv_has_readonly_bitmaps(bs) &&
+            !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE))
+        {
+            bool header_updated = false;
+            qcow2_reopen_bitmaps_rw_hint(bs, &header_updated, &local_err);
+            update_header = update_header && !header_updated;
+        }
+    } else if (qcow2_load_dirty_bitmaps(bs, &local_err)) {
         update_header = false;
     }
     if (local_err != NULL) {
diff --git a/block/qcow2.h b/block/qcow2.h
index ccb92a9696d8a0205aaa59b011ab954cbd2b0a4a..d301f77cea57d305b4a18bf861b38a7fb68c2f3e 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -671,6 +671,8 @@ int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
                                   void **refcount_table,
                                   int64_t *refcount_table_size);
 bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp);
+int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,
+                                 Error **errp);
 int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp);
 void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp);
 int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp);
diff --git a/block/vmdk.c b/block/vmdk.c
index f94c49a9c0d8e734289fc4e61d72df813cbe4bcf..84f8bbe480cbf944e87145af0b3bbd0617d52a80 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -47,6 +47,8 @@
 #define VMDK4_FLAG_MARKER (1 << 17)
 #define VMDK4_GD_AT_END 0xffffffffffffffffULL
 
+#define VMDK_EXTENT_MAX_SECTORS (1ULL << 32)
+
 #define VMDK_GTE_ZEROED 0x1
 
 /* VMDK internal error codes */
@@ -1250,6 +1252,10 @@ static int get_cluster_offset(BlockDriverState *bs,
             return zeroed ? VMDK_ZEROED : VMDK_UNALLOC;
         }
 
+        if (extent->next_cluster_sector >= VMDK_EXTENT_MAX_SECTORS) {
+            return VMDK_ERROR;
+        }
+
         cluster_sector = extent->next_cluster_sector;
         extent->next_cluster_sector += extent->cluster_sectors;
 
diff --git a/tests/qemu-iotests/169 b/tests/qemu-iotests/169
index 3a8db91f6f9337d1024a653984388187e388f710..153b10b6e75844f897621c3f11c8263020c1e875 100755
--- a/tests/qemu-iotests/169
+++ b/tests/qemu-iotests/169
@@ -140,16 +140,14 @@ def inject_test_case(klass, name, method, *args, **kwargs):
     mc = operator.methodcaller(method, *args, **kwargs)
     setattr(klass, 'test_' + name, new.instancemethod(mc, None, klass))
 
-for cmb in list(itertools.product((True, False), repeat=3)):
+for cmb in list(itertools.product((True, False), repeat=4)):
     name = ('_' if cmb[0] else '_not_') + 'persistent_'
     name += ('_' if cmb[1] else '_not_') + 'migbitmap_'
     name += '_online' if cmb[2] else '_offline'
-
-    # TODO fix shared-storage bitmap migration and enable cases for it
-    args = list(cmb) + [False]
+    name += '_shared' if cmb[3] else '_nonshared'
 
     inject_test_case(TestDirtyBitmapMigration, name, 'do_test_migration',
-                     *args)
+                     *list(cmb))
 
 
 if __name__ == '__main__':
diff --git a/tests/qemu-iotests/169.out b/tests/qemu-iotests/169.out
index 594c16f49f2732b12af4f63193319d38be583876..b6f257674e9122cb4721d30059ded516bcdc6786 100644
--- a/tests/qemu-iotests/169.out
+++ b/tests/qemu-iotests/169.out
@@ -1,5 +1,5 @@
-........
+................
 ----------------------------------------------------------------------
-Ran 8 tests
+Ran 16 tests
 
 OK