On 04/26/2017 01:25 AM, lixiubo@xxxxxxxxxxxxxxxxxxxx wrote: > for_each_sg(data_sg, sg, data_nents, i) { > @@ -275,22 +371,26 @@ static void alloc_and_scatter_data_area(struct tcmu_dev *udev, > from = kmap_atomic(sg_page(sg)) + sg->offset; > while (sg_remaining > 0) { > if (block_remaining == 0) { > - block = find_first_zero_bit(udev->data_bitmap, > - DATA_BLOCK_BITS); > block_remaining = DATA_BLOCK_SIZE; > - set_bit(block, udev->data_bitmap); > + dbi = tcmu_get_empty_block(udev, &to); > + if (dbi < 0) I know it you fixed the missing kunmap_atomic here and missing unlock in tcmu_queue_cmd_ring in the next patch, but I think normally people prefer that one patch does not add a bug, then the next patch fixes it.