Add a regression test to check that forced unmounts work correctly.

Bug described in PR kern/5683

regress/sys/kern/Makefile

@@ -1,6 +1,6 @@
-#	$NetBSD: Makefile,v 1.21 2003/01/30 19:47:00 thorpej Exp $
+#	$NetBSD: Makefile,v 1.22 2003/04/15 06:19:57 erh Exp $
 
 SUBDIR+= execve extent getcwd ipf kqueue lock lockf pipe poll ras \
-	sigtramp sysvmsg sysvsem sysvshm ucontext unfdpass writev
+	sigtramp sysvmsg sysvsem sysvshm ucontext umount unfdpass writev
 
 .include <bsd.subdir.mk>

regress/sys/kern/umount/Makefile

@@ -0,0 +1,53 @@
+# $NetBSD: Makefile,v 1.1 2003/04/15 06:19:59 erh Exp $
+#
+#  This test creates and mounts a temporary filesystem.  Then it
+#  forcibly unmounts it while in the mount point and checks that
+#  things work as expected.
+#
+
+.include <bsd.own.mk>
+
+TMPMP=${.OBJDIR}/umount-f_mount
+TMPIM=${.OBJDIR}/umount-f.im
+
+VND?= vnd0
+BVND= /dev/${VND}
+CVND= /dev/r${VND}
+MPART?= a
+
+regress: mountfs run_script clean
+
+clean:
+	@echo "***  Cleaning up ${TMPMP}, ${TMPIM}."
+	-umount -f "${TMPMP}"
+	-vnconfig -u "${VND}"
+	-rm -rf "${TMPMP}" "${TMPIM}"
+
+mountfs:
+	@mkdir ${TMPMP}
+	@touch ${TMPMP}/under_the_mount
+	@echo "***  Creating a dummy directory tree at ${TMPMP} monted on" \
+	    "${TMPIM}"
+	@dd if=/dev/zero of=${TMPIM} count=5860
+	@vnconfig -v ${VND} ${TMPIM}
+	@disklabel -f ${.CURDIR}/disktab -rw ${VND} floppy288
+	@newfs -i 500 -b 8192 -f 1024 ${CVND}${MPART}
+	@mount -o async ${BVND}${MPART} ${TMPMP}
+	@touch ${TMPMP}/in_mounted_directory
+
+
+run_script:
+	@echo "***  Testing forced unmount"
+	@if [ ! -e "${TMPMP}/in_mounted_directory" ] ; then \
+		echo "Test file not present in mounted directory!" ;\
+		false ;\
+	fi
+	@cd "${TMPMP}" && umount -f "${BVND}${MPART}" && \
+	 sh ${.CURDIR}/check_umount.sh
+	@if [ ! -e "${TMPMP}/under_the_mount" ]; then \
+		echo "Original mount point dissapeared!" ;\
+		false ;\
+	fi
+	@echo "***  SUCCESS"
+
+.include <bsd.obj.mk>

regress/sys/kern/umount/check_umount.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+# $NetBSD: check_umount.sh,v 1.1 2003/04/15 06:19:59 erh Exp $
+
+# This script expects to be run with the current directory
+# set to a location that has just been forcibly unmounted.
+
+retval=0
+
+checkit()
+{
+	OUTPUT=`$CMD 2>&1`
+	if [ "$OUTPUT" != "$EXPECT" ] ; then
+		retval=1
+		echo "Command \"$CMD\" failed:"
+		echo "OUTPUT: $OUTPUT"
+		echo "EXPECTED: $EXPECT"
+	fi
+}
+
+CMD="ls ."
+EXPECT="ls: .: No such file or directory"
+checkit
+CMD="ls .."
+EXPECT="ls: ..: No such file or directory"
+checkit
+CMD="cd ."
+EXPECT="cd: can't cd to ."
+checkit
+CMD="cd .."
+EXPECT="cd: can't cd to .."
+checkit
+
+exit $retval

regress/sys/kern/umount/disktab

@@ -0,0 +1,7 @@
+#	$NetBSD: disktab,v 1.1 2003/04/15 06:19:59 erh Exp $
+
+floppy288|2.88MB 3.5in Extra High Density Floppy:\
+	:ty=floppy:se#512:nt#2:rm#300:ns#36:nc#80:\
+	:pa#5760:oa#0:ba#4096:fa#512:ta=4.2BSD:\
+	:pb#5760:ob#0:\
+	:pc#5760:oc#0: