[PATCH blktests] tests/block/031: Add a test for sharing a tag set across hardware queues

[Bart Van Assche <bvanassche@acm.org>]

Support for sharing a tag set across hardware queues has been added
recently to the Linux kernel. See also the BLK_MQ_F_TAG_HCTX_SHARED flag,
Linux kernel commit 32bc15afed04 ("blk-mq: Facilitate a shared sbitmap per
tagset"; v5.10) and commit 0905053bdb5b ("null_blk: Support shared tag
bitmap"; v5.10). Add a test that triggers the shared tag set code in the
block layer core.

Cc: John Garry <john.garry@huawei.com>
Cc: Don Brace<don.brace@microsemi.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 tests/block/031     | 43 +++++++++++++++++++++++++++++++++++++++++++
 tests/block/031.out |  1 +
 2 files changed, 44 insertions(+)
 create mode 100755 tests/block/031
 create mode 100644 tests/block/031.out

diff --git a/tests/block/031 b/tests/block/031
new file mode 100755
index 000000000000..7940f9fa1114
--- /dev/null
+++ b/tests/block/031
@@ -0,0 +1,43 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2021 Google LLC
+#
+# Test support for sharing a tag set across hardware queues ("host tag set").
+
+. tests/block/rc
+. common/null_blk
+
+DESCRIPTION="test host tagset support"
+TIMED=1
+
+requires() {
+	_have_null_blk && _have_module_param null_blk shared_tag_bitmap
+}
+
+test() {
+	local fio_status bs=512
+
+	: "${TIMEOUT:=30}"
+	if ! _init_null_blk nr_devices=0 queue_mode=2 shared_tag_bitmap=1; then
+		echo "Loading null_blk failed"
+		return 1
+	fi
+	if ! _configure_null_blk nullb0 completion_nsec=0 blocksize=$bs size=1\
+	     submit_queues="$(nproc)" memory_backed=1 power=1; then
+		echo "Configuring null_blk failed"
+		return 1
+	fi
+	fio --verify=md5 --rw=randwrite --bs=$bs --loops=$((10**6)) \
+		--iodepth=64 --group_reporting --sync=1 --direct=1 \
+		--ioengine=libaio --runtime="${TIMEOUT}" --thread \
+		--name=block-031 --filename=/dev/nullb0 \
+		--output="${RESULTS_DIR}/block/fio-output-031.txt" \
+		>>"$FULL"
+	fio_status=$?
+	rmdir /sys/kernel/config/nullb/nullb0
+	_exit_null_blk
+	case $fio_status in
+		0) echo "Passed";;
+		*) echo "Failed (fio status = $fio_status)";;
+	esac
+}
diff --git a/tests/block/031.out b/tests/block/031.out
new file mode 100644
index 000000000000..863339fb8ced
--- /dev/null
+++ b/tests/block/031.out
@@ -0,0 +1 @@
+Passed