block: Use common req handling in copy offloading

This brings the request handling logic inline with write and discard,
fixing write_gen, resize_cb, dirty bitmaps and image size refreshing.
The last of these issues broke iotest case 222, which is now fixed.
Signed-off-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/io.c

@@ -3030,20 +3030,16 @@ static int coroutine_fn bdrv_co_copy_range_internal(
         bdrv_inc_in_flight(dst->bs);
         tracked_request_begin(&req, dst->bs, dst_offset, bytes,
                               BDRV_TRACKED_WRITE);
-
-        /* BDRV_REQ_NO_SERIALISING is only for read operation */
-        assert(!(write_flags & BDRV_REQ_NO_SERIALISING));
-        if (write_flags & BDRV_REQ_SERIALISING) {
-            mark_request_serialising(&req, bdrv_get_cluster_size(dst->bs));
-        }
-        wait_serialising_requests(&req);
-
+        ret = bdrv_co_write_req_prepare(dst, dst_offset, bytes, &req,
+                                        write_flags);
+        if (!ret) {
             ret = dst->bs->drv->bdrv_co_copy_range_to(dst->bs,
                                                       src, src_offset,
                                                       dst, dst_offset,
                                                       bytes,
                                                       read_flags, write_flags);
-
+        }
+        bdrv_co_write_req_finish(dst, dst_offset, bytes, &req, ret);
         tracked_request_end(&req);
         bdrv_dec_in_flight(dst->bs);
     }