selftests: ublk: add test for checking zero copy related parameter

ublk zero copy usually requires to set dma and segment parameter correctly,
so hard-code null target's dma & segment parameter in non-default value,
and verify if they are setup correctly by ublk driver.

Signed-off-by: Ming Lei <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

tools/testing/selftests/ublk/Makefile

···
 
 TEST_PROGS := test_generic_01.sh
 TEST_PROGS += test_generic_02.sh
+TEST_PROGS += test_generic_03.sh
 
 TEST_PROGS += test_null_01.sh
 TEST_PROGS += test_null_02.sh

tools/testing/selftests/ublk/null.c

···
 
 	dev->tgt.dev_size = dev_size;
 	dev->tgt.params = (struct ublk_params) {
-		.types = UBLK_PARAM_TYPE_BASIC,
+		.types = UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DMA_ALIGN |
+			UBLK_PARAM_TYPE_SEGMENT,
 		.basic = {
 			.logical_bs_shift	= 9,
 			.physical_bs_shift	= 12,
···
 			.io_min_shift		= 9,
 			.max_sectors		= info->max_io_buf_bytes >> 9,
 			.dev_sectors		= dev_size >> 9,
+		},
+		.dma = {
+			.alignment 		= 4095,
+		},
+		.seg = {
+			.seg_boundary_mask 	= 4095,
+			.max_segment_size 	= 32 << 10,
+			.max_segments 		= 32,
 		},
 	};
 

tools/testing/selftests/ublk/test_generic_03.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh
+
+TID="generic_03"
+ERR_CODE=0
+
+_prep_test "null" "check dma & segment limits for zero copy"
+
+dev_id=$(_add_ublk_dev -t null -z)
+_check_add_dev $TID $?
+
+sysfs_path=/sys/block/ublkb"${dev_id}"
+dma_align=$(cat "$sysfs_path"/queue/dma_alignment)
+max_segments=$(cat "$sysfs_path"/queue/max_segments)
+max_segment_size=$(cat "$sysfs_path"/queue/max_segment_size)
+if [ "$dma_align" != "4095" ]; then
+	ERR_CODE=255
+fi
+if [ "$max_segments" != "32" ]; then
+	ERR_CODE=255
+fi
+if [ "$max_segment_size" != "32768" ]; then
+	ERR_CODE=255
+fi
+_cleanup_test "null"
+_show_result $TID $ERR_CODE