selftests: ublk: add integrity data support to loop target

To perform and end-to-end test of integrity information through a ublk
device, we need to actually store it somewhere and retrieve it. Add this
support to kublk's loop target. It uses a second backing file for the
integrity data corresponding to the data stored in the first file.
The integrity file is initialized with byte 0xFF, which ensures the app
and reference tags are set to the "escape" pattern to disable the
bio-integrity-auto guard and reftag checks until the blocks are written.
The integrity file is opened without O_DIRECT since it will be accessed
at sub-block granularity. Each incoming read/write results in a pair of
reads/writes, one to the data file, and one to the integrity file. If
either backing I/O fails, the error is propagated to the ublk request.
If both backing I/Os read/write some bytes, the ublk request is
completed with the smaller of the number of blocks accessed by each I/O.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: calebsander

tools/testing/selftests/ublk/file_backed.c

@@ -35,24 +35,38 @@ static int loop_queue_tgt_rw_io(struct ublk_thread *t, struct ublk_queue *q,
 	unsigned auto_zc = ublk_queue_use_auto_zc(q);
 	enum io_uring_op op = ublk_to_uring_op(iod, zc | auto_zc);
 	struct ublk_io *io = ublk_get_io(q, tag);
+	__u64 offset = iod->start_sector << 9;
+	__u32 len = iod->nr_sectors << 9;
 	struct io_uring_sqe *sqe[3];
 	void *addr = io->buf_addr;
 
+	if (iod->op_flags & UBLK_IO_F_INTEGRITY) {
+		ublk_io_alloc_sqes(t, sqe, 1);
+		/* Use second backing file for integrity data */
+		io_uring_prep_rw(op, sqe[0], ublk_get_registered_fd(q, 2),
+				 io->integrity_buf,
+				 ublk_integrity_len(q, len),
+				 ublk_integrity_len(q, offset));
+		sqe[0]->flags = IOSQE_FIXED_FILE;
+		/* tgt_data = 1 indicates integrity I/O */
+		sqe[0]->user_data = build_user_data(tag, ublk_op, 1, q->q_id, 1);
+	}
+
 	if (!zc || auto_zc) {
 		ublk_io_alloc_sqes(t, sqe, 1);
 		if (!sqe[0])
 			return -ENOMEM;
 
 		io_uring_prep_rw(op, sqe[0], ublk_get_registered_fd(q, 1) /*fds[1]*/,
 				addr,
-				iod->nr_sectors << 9,
-				iod->start_sector << 9);
+				len,
+				offset);
 		if (auto_zc)
 			sqe[0]->buf_index = tag;
 		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, q->q_id, 1);
-		return 1;
+		return !!(iod->op_flags & UBLK_IO_F_INTEGRITY) + 1;
 	}
 
 	ublk_io_alloc_sqes(t, sqe, 3);
@@ -63,16 +77,16 @@ static int loop_queue_tgt_rw_io(struct ublk_thread *t, struct ublk_queue *q,
 			ublk_cmd_op_nr(sqe[0]->cmd_op), 0, q->q_id, 1);
 
 	io_uring_prep_rw(op, sqe[1], ublk_get_registered_fd(q, 1) /*fds[1]*/, 0,
-		iod->nr_sectors << 9,
-		iod->start_sector << 9);
+			len,
+			offset);
 	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, q->q_id, 1);
 
 	io_uring_prep_buf_unregister(sqe[2], q, tag, q->q_id, io->buf_index);
 	sqe[2]->user_data = build_user_data(tag, ublk_cmd_op_nr(sqe[2]->cmd_op), 0, q->q_id, 1);
 
-	return 2;
+	return !!(iod->op_flags & UBLK_IO_F_INTEGRITY) + 2;
 }
 
 static int loop_queue_tgt_io(struct ublk_thread *t, struct ublk_queue *q, int tag)
@@ -119,12 +133,17 @@ static void ublk_loop_io_done(struct ublk_thread *t, struct ublk_queue *q,
 	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);
+	if (cqe->res < 0) {
+		io->result = cqe->res;
+		ublk_err("%s: io failed op %x user_data %lx\n",
+				__func__, op, cqe->user_data);
+	} else if (op != ublk_cmd_op_nr(UBLK_U_IO_UNREGISTER_IO_BUF)) {
+		__s32 data_len = user_data_to_tgt_data(cqe->user_data)
+			? ublk_integrity_data_len(q, cqe->res)
+			: cqe->res;
+
+		if (!io->result || data_len < io->result)
+			io->result = data_len;
 	}
 
 	/* buffer register op is IOSQE_CQE_SKIP_SUCCESS */
@@ -135,9 +154,30 @@ static void ublk_loop_io_done(struct ublk_thread *t, struct ublk_queue *q,
 		ublk_complete_io(t, q, tag, io->result);
 }
 
+static int ublk_loop_memset_file(int fd, __u8 byte, size_t len)
+{
+	off_t offset = 0;
+	__u8 buf[4096];
+
+	memset(buf, byte, sizeof(buf));
+	while (len) {
+		int ret = pwrite(fd, buf, min(len, sizeof(buf)), offset);
+
+		if (ret < 0)
+			return -errno;
+		if (!ret)
+			return -EIO;
+
+		len -= ret;
+		offset += ret;
+	}
+	return 0;
+}
+
 static int ublk_loop_tgt_init(const struct dev_ctx *ctx, struct ublk_dev *dev)
 {
 	unsigned long long bytes;
+	unsigned long blocks;
 	int ret;
 	struct ublk_params p = {
 		.types = UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DMA_ALIGN,
@@ -154,23 +194,39 @@ static int ublk_loop_tgt_init(const struct dev_ctx *ctx, struct ublk_dev *dev)
 		},
 	};
 
+	ublk_set_integrity_params(ctx, &p);
 	if (ctx->auto_zc_fallback) {
 		ublk_err("%s: not support auto_zc_fallback\n", __func__);
 		return -EINVAL;
 	}
-	if (ctx->metadata_size) {
-		ublk_err("%s: integrity not supported\n", __func__);
-		return -EINVAL;
-	}
 
+	/* Use O_DIRECT only for data file */
 	ret = backing_file_tgt_init(dev, 1);
 	if (ret)
 		return ret;
 
-	if (dev->tgt.nr_backing_files != 1)
+	/* Expect a second file for integrity data */
+	if (dev->tgt.nr_backing_files != 1 + !!ctx->metadata_size)
 		return -EINVAL;
 
-	bytes = dev->tgt.backing_file_size[0];
+	blocks = dev->tgt.backing_file_size[0] >> p.basic.logical_bs_shift;
+	if (ctx->metadata_size) {
+		unsigned long metadata_blocks =
+			dev->tgt.backing_file_size[1] / ctx->metadata_size;
+		unsigned long integrity_len;
+
+		/* Ensure both data and integrity data fit in backing files */
+		blocks = min(blocks, metadata_blocks);
+		integrity_len = blocks * ctx->metadata_size;
+		/*
+		 * Initialize PI app tag and ref tag to 0xFF
+		 * to disable bio-integrity-auto checks
+		 */
+		ret = ublk_loop_memset_file(dev->fds[2], 0xFF, integrity_len);
+		if (ret)
+			return ret;
+	}
+	bytes = blocks << p.basic.logical_bs_shift;
 	dev->tgt.dev_size = bytes;
 	p.basic.dev_sectors = bytes >> 9;
 	dev->tgt.params = p;