1 files changed, 169 insertions, 0 deletions
diff --git a/tools/testing/selftests/ublk/file_backed.c b/tools/testing/selftests/ublk/file_backed.c
new file mode 100644
index 000000000000..6f34eabfae97
--- /dev/null
+++ b/tools/testing/selftests/ublk/file_backed.c
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "kublk.h"
+
+static enum io_uring_op ublk_to_uring_op(const struct ublksrv_io_desc *iod, int zc)
+{
+	unsigned ublk_op = ublksrv_get_op(iod);
+
+	if (ublk_op == UBLK_IO_OP_READ)
+		return zc ? IORING_OP_READ_FIXED : IORING_OP_READ;
+	else if (ublk_op == UBLK_IO_OP_WRITE)
+		return zc ? IORING_OP_WRITE_FIXED : IORING_OP_WRITE;
+	assert(0);
+}
+
+static int loop_queue_flush_io(struct ublk_queue *q, const struct ublksrv_io_desc *iod, int tag)
+{
+	unsigned ublk_op = ublksrv_get_op(iod);
+	struct io_uring_sqe *sqe[1];
+
+	ublk_queue_alloc_sqes(q, sqe, 1);
+	io_uring_prep_fsync(sqe[0], 1 /*fds[1]*/, IORING_FSYNC_DATASYNC);
+	io_uring_sqe_set_flags(sqe[0], IOSQE_FIXED_FILE);
+	/* bit63 marks us as tgt io */
+	sqe[0]->user_data = build_user_data(tag, ublk_op, 0, 1);
+	return 1;
+}
+
+static int loop_queue_tgt_rw_io(struct ublk_queue *q, const struct ublksrv_io_desc *iod, int tag)
+{
+	unsigned ublk_op = ublksrv_get_op(iod);
+	int zc = ublk_queue_use_zc(q);
+	enum io_uring_op op = ublk_to_uring_op(iod, zc);
+	struct io_uring_sqe *sqe[3];
+
+	if (!zc) {
+		ublk_queue_alloc_sqes(q, sqe, 1);
+		if (!sqe[0])
+			return -ENOMEM;
+
+		io_uring_prep_rw(op, sqe[0], 1 /*fds[1]*/,
+				(void *)iod->addr,
+				iod->nr_sectors << 9,
+				iod->start_sector << 9);
+		io_uring_sqe_set_flags(sqe[0], IOSQE_FIXED_FILE);
+		/* bit63 marks us as tgt io */
+		sqe[0]->user_data = build_user_data(tag, ublk_op, 0, 1);
+		return 1;
+	}
+
+	ublk_queue_alloc_sqes(q, sqe, 3);
+
+	io_uring_prep_buf_register(sqe[0], 0, tag, q->q_id, tag);
+	sqe[0]->flags |= IOSQE_CQE_SKIP_SUCCESS | IOSQE_IO_HARDLINK;
+	sqe[0]->user_data = build_user_data(tag,
+			ublk_cmd_op_nr(sqe[0]->cmd_op), 0, 1);
+
+	io_uring_prep_rw(op, sqe[1], 1 /*fds[1]*/, 0,
+		iod->nr_sectors << 9,
+		iod->start_sector << 9);
+	sqe[1]->buf_index = tag;
+	sqe[1]->flags |= IOSQE_FIXED_FILE | IOSQE_IO_HARDLINK;
+	sqe[1]->user_data = build_user_data(tag, ublk_op, 0, 1);
+
+	io_uring_prep_buf_unregister(sqe[2], 0, tag, q->q_id, tag);
+	sqe[2]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[2]->cmd_op), 0, 1);
+
+	return 2;
+}
+
+static int loop_queue_tgt_io(struct ublk_queue *q, int tag)
+{
+	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);
+	unsigned ublk_op = ublksrv_get_op(iod);
+	int ret;
+
+	switch (ublk_op) {
+	case UBLK_IO_OP_FLUSH:
+		ret = loop_queue_flush_io(q, iod, tag);
+		break;
+	case UBLK_IO_OP_WRITE_ZEROES:
+	case UBLK_IO_OP_DISCARD:
+		ret = -ENOTSUP;
+		break;
+	case UBLK_IO_OP_READ:
+	case UBLK_IO_OP_WRITE:
+		ret = loop_queue_tgt_rw_io(q, iod, tag);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	ublk_dbg(UBLK_DBG_IO, "%s: tag %d ublk io %x %llx %u\n", __func__, tag,
+			iod->op_flags, iod->start_sector, iod->nr_sectors << 9);
+	return ret;
+}
+
+static int ublk_loop_queue_io(struct ublk_queue *q, int tag)
+{
+	int queued = loop_queue_tgt_io(q, tag);
+
+	ublk_queued_tgt_io(q, tag, queued);
+	return 0;
+}
+
+static void ublk_loop_io_done(struct ublk_queue *q, int tag,
+		const struct io_uring_cqe *cqe)
+{
+	unsigned op = user_data_to_op(cqe->user_data);
+	struct ublk_io *io = ublk_get_io(q, tag);
+
+	if (cqe->res < 0 || op != ublk_cmd_op_nr(UBLK_U_IO_UNREGISTER_IO_BUF)) {
+		if (!io->result)
+			io->result = cqe->res;
+		if (cqe->res < 0)
+			ublk_err("%s: io failed op %x user_data %lx\n",
+					__func__, op, cqe->user_data);
+	}
+
+	/* buffer register op is IOSQE_CQE_SKIP_SUCCESS */
+	if (op == ublk_cmd_op_nr(UBLK_U_IO_REGISTER_IO_BUF))
+		io->tgt_ios += 1;
+
+	if (ublk_completed_tgt_io(q, tag))
+		ublk_complete_io(q, tag, io->result);
+}
+
+static int ublk_loop_tgt_init(const struct dev_ctx *ctx, struct ublk_dev *dev)
+{
+	unsigned long long bytes;
+	int ret;
+	struct ublk_params p = {
+		.types = UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DMA_ALIGN,
+		.basic = {
+			.attrs = UBLK_ATTR_VOLATILE_CACHE,
+			.logical_bs_shift	= 9,
+			.physical_bs_shift	= 12,
+			.io_opt_shift	= 12,
+			.io_min_shift	= 9,
+			.max_sectors = dev->dev_info.max_io_buf_bytes >> 9,
+		},
+		.dma = {
+			.alignment = 511,
+		},
+	};
+
+	ret = backing_file_tgt_init(dev);
+	if (ret)
+		return ret;
+
+	if (dev->tgt.nr_backing_files != 1)
+		return -EINVAL;
+
+	bytes = dev->tgt.backing_file_size[0];
+	dev->tgt.dev_size = bytes;
+	p.basic.dev_sectors = bytes >> 9;
+	dev->tgt.params = p;
+
+	return 0;
+}
+
+const struct ublk_tgt_ops loop_tgt_ops = {
+	.name = "loop",
+	.init_tgt = ublk_loop_tgt_init,
+	.deinit_tgt = backing_file_tgt_deinit,
+	.queue_io = ublk_loop_queue_io,
+	.tgt_io_done = ublk_loop_io_done,
+};