stress2: Added a regression test

tools/test/stress2/misc/nullfs29.sh

@@ -0,0 +1,77 @@
+#!/bin/sh
+
+# Regression test for:
+# bf13db086b84 - main - Mostly revert a5970a529c2d95271: Make files opened
+# with O_PATH to not block non-forced unmount
+
+# Based on a scenario by: ambrisko
+
+[ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
+
+. ../default.cfg
+
+here=`pwd`
+mp1=$mntpoint
+mp2=${mntpoint}$mdstart
+
+set -e
+mount | grep $mntpoint | grep -q /dev/md && umount -f $mntpoint
+mdconfig -l | grep -q md$mdstart &&  mdconfig -d -u $mdstart
+mdconfig -a -t swap -s 1g -u $mdstart || exit 1
+newfs $newfs_flags md$mdstart > /dev/null
+mount /dev/md$mdstart $mntpoint
+chmod 777 $mntpoint
+
+mkdir -p $mp2
+mount_nullfs -o nocache $mp1 $mp2
+set +e
+cat > /tmp/nullfs29.c <<EOF
+#include <sys/stat.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int
+main(void) {
+	int new_dir, new_file, ret;
+	struct stat sb;
+	char *dir = "test2";
+	char *path= "test2/what2";
+
+	if (mkdir(dir, 0755) == -1)
+		err(1, "mkdir(test2)");
+	new_dir = openat(AT_FDCWD, dir, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_PATH, 0700);
+	if (new_dir == -1)
+		err(1, "openat(%s)", dir);
+
+	ret = fstatat(new_dir, "what2", &sb, AT_SYMLINK_NOFOLLOW);
+	if (ret == 0)
+		errx(1, "Expected fstatat() to fail");
+	if (ret == -1 && errno != ENOENT)
+		err(1, "fstatat(%s)", dir);
+
+	close(new_dir);
+	new_file = openat(AT_FDCWD, path, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0644);
+	if (new_file== -1)
+		err(1, "openat(%s)", path);
+}
+
+EOF
+mycc -o /tmp/nullfs29 -Wall -Wextra -O2 /tmp/nullfs29.c || exit 1
+cd $mp2
+/tmp/nullfs29; s=$?
+cd $here
+umount $mp2
+
+n=0
+while mount | grep $mp1 | grep -q /dev/md; do
+	umount $mp1 || sleep 1
+	n=$((n + 1))
+	[ $n -gt 30 ] && { echo FAIL; s=2; }
+done
+mdconfig -d -u $mdstart
+rm -f /tmp/nullfs29.c
+exit $s