Re: [PATCH V2 3/3] selftests: ublk: add ublk zero copy test

On Wed, Feb 26, 2025 at 11:58:38PM +0800, Ming Lei wrote:

• struct io_uring_sqe *reg;
• struct io_uring_sqe *rw;
• struct io_uring_sqe *ureg;
• if (!zc) {

• rw = ublk_queue_alloc_sqe(q);
  

• if (!rw)
  

• 	return -ENOMEM;
  

• io_uring_prep_rw(op, rw, 1 /*fds[1]*/,
  

• 		(void *)iod->addr,
  

• 		iod->nr_sectors << 9,
  

• 		iod->start_sector << 9);
  

• io_uring_sqe_set_flags(rw, IOSQE_FIXED_FILE);
  

• q->io_inflight++;
  

• /* bit63 marks us as tgt io */
  

• rw->user_data = build_user_data(tag, op, UBLK_IO_TGT_NORMAL, 1);
  

• return 0;
  

• }
• ublk_queue_alloc_sqe3(q, &reg, &rw, &ureg);
• io_uring_prep_buf_register(reg, 0, tag, q->q_id, tag);
• reg->user_data = build_user_data(tag, 0xfe, 1, 1);
• reg->flags |= IOSQE_CQE_SKIP_SUCCESS;
• reg->flags |= IOSQE_IO_LINK;
• io_uring_prep_rw(op, rw, 1 /*fds[1]*/, 0,

• iod->nr_sectors << 9,
  

• iod->start_sector << 9);
  

• rw->buf_index = tag;
• rw->flags |= IOSQE_FIXED_FILE;
• rw->flags |= IOSQE_IO_LINK;
• rw->user_data = build_user_data(tag, op, UBLK_IO_TGT_ZC_OP, 1);
• q->io_inflight++;
• io_uring_prep_buf_unregister(ureg, 0, tag, q->q_id, tag);
• ureg->user_data = build_user_data(tag, 0xff, UBLK_IO_TGT_ZC_BUF, 1);

You don't have anything handling the unregister command's completion so I think you want the IOSQE_CQE_SKIP_SUCCESS flag on it otherwise you get an unexpected CQE for it.