nvme: add test for controller rescan under I/O load

Add a test that repeatedly rescans nvme controllers while doing IO
on an nvme namespace connected to these controllers. The purpose
of the test is to make sure that no I/O errors or data corruption
occurs because of the rescan operations. The test uses sub-second
sleeps, which can't be easily accomplished in bash because of
missing floating-point arithmetic (and because usleep(1) isn't
portable). Therefore an awk program is used to trigger the
device rescans.

Link: https://lore.kernel.org/linux-nvme/[email protected]/
Signed-off-by: Martin Wilck <[email protected]>
Signed-off-by: Shin'ichiro Kawasaki <[email protected]>

tests/nvme/053

@@ -0,0 +1,76 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2024 Martin Wilck, SUSE LLC
+#
+# Repeatedly rescans nvme controllers while doing IO on an nvme namespace
+# connected to these controllers, and make sure that no I/O errors or data
+# corruption occurs.
+
+. tests/nvme/rc
+
+DESCRIPTION="test controller rescan under I/O load"
+TIMED=1
+: "${TIMEOUT:=60}"
+
+rescan_controller() {
+	local path
+	path="$1/rescan_controller"
+
+	[[ -f "$path" ]] || {
+		echo "cannot rescan $1"
+		return 1
+	}
+
+	awk -f "$TMPDIR/rescan.awk" \
+	    -v path="$path" -v timeout="$TIMEOUT" -v seed="$2" &
+}
+
+create_rescan_script() {
+	cat >"$TMPDIR/rescan.awk" <<EOF
+@load "time"
+
+BEGIN {
+    srand(seed);
+    finish = gettimeofday() + strtonum(timeout);
+    while (gettimeofday() < finish) {
+	sleep(0.1 + 5 * rand());
+	printf("1\n") > path;
+	close(path);
+    }
+}
+EOF
+}
+
+test_device() {
+	local -a ctrls
+	local i st line
+
+	echo "Running ${TEST_NAME}"
+	create_rescan_script
+
+	while IFS= read -r line; do
+		ctrls+=("$line")
+	done < <(_nvme_get_ctrl_list)
+	_run_fio_verify_io --filename="$TEST_DEV" --time_based &> "$FULL" &
+
+	for i in "${!ctrls[@]}"; do
+		rescan_controller "${ctrls[$i]}" "$i"
+	done
+
+	while true; do
+		wait -n &>/dev/null
+		st=$?
+		case $st in
+			127)
+				break
+				;;
+			0)
+				;;
+			*)
+				echo "child process exited with $st!"
+				;;
+		esac
+	done
+
+	echo "Test complete"
+}

tests/nvme/053.out

@@ -0,0 +1,2 @@
+Running nvme/053
+Test complete

tests/nvme/rc

@@ -192,6 +192,24 @@ _test_dev_nvme_nsid() {
 	cat "${TEST_DEV_SYSFS}/nsid"
 }
 
+_nvme_get_ctrl_list() {
+	local subsys
+	local c
+
+	subsys=$(readlink  "${TEST_DEV_SYSFS}/device/subsystem")
+	case $subsys in
+		*/nvme)
+			readlink -f "${TEST_DEV_SYSFS}/device"
+			;;
+		*/nvme-subsystem)
+			for c in "${TEST_DEV_SYSFS}"/device/nvme*; do
+				[[ -L "$c" ]] || continue
+				[[ -f "$c/dev" ]] && readlink -f "$c"
+			done
+			;;
+	esac
+}
+
 _nvme_calc_rand_io_size() {
 	local img_size_mb
 	local io_size_kb