Attachment 237865 Details for Bug 255047 – script to reproduce the bug

script to reproduce the bug

fsidbug.sh (text/plain), 1.76 KB, created by Olivier Cochard on 2022-11-04 21:26:48 UTC

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Creator: Olivier Cochard

Created: 2022-11-04 21:26:48 UTC

Size: 1.76 KB

patch

obsolete

>#!/bin/sh
># Reproduce duplicate fsid race triggering umounting wrong directory
>
>set -euo pipefail
>
>mount_race () {
>	# Mounting the raw disk image, writing 4M into it and umounting it
>	n=$1
>	echo "[$n] Copying /tmp/mount_bug into /tmp/$n..."
>	cp /tmp/mount_bug /tmp/$n
>	echo "[$n] Creating md device..."
>	MD=$(mdconfig -a -t vnode -f /tmp/$1)
>	echo "[$n] mount ${MD} into /tmp/$n.mnt..."
>	mkdir -p /tmp/$n.mnt
>	mount /dev/${MD} /tmp/$n.mnt
>	FSID=$(dumpfs /tmp/$n.mnt | grep -w id)
>	echo "[$n] fsid of the mount point /tmp/$n.mnt/: ${FSID}"
>	echo "[$n] Creating a file into it /tmp/$n.mnt/..."
>	truncate -s +4M /tmp/$n.mnt/dummy
>	echo "[$n] umount /tmp/$n.mnt..."
>	if ! umount /tmp/$n.mnt; then
>		echo "[$n] umount of /tmp/$n.mnt failed because:"
>		echo "[$n] 1) it umounted the wrong mount point (same fsid as the 'other') used by the other process"
>		echo "[$n] 2) or it was already wrongly umounted by the other process"
>	else
>		echo "[$n] umount sucessfull, destroying md device $MD..."
>		if ! mdconfig -d -u ${MD}; then
>			echo "[$n] destroying md device ${MD} failed (because still mounted, the previous umount did it on the wrong directory)"
>		fi
>	fi
>	echo "[$n] cleaning up..."
>	# Those will fails, then the set -e will stop full script
>	rm -rf /tmp/$n.mnt
>	rm /tmp/$n
>}
>
>init_disk_image () {
>	echo "[init] Creating 6MB raw UFS disk file in /tmp/mount_bug..."
>	rm -rf /tmp/mount_bug
>	truncate -s +6M /tmp/mount_bug
>	MD=$(mdconfig -a -t vnode -f /tmp/mount_bug)
>	newfs /dev/$MD > /dev/null
>	mdconfig -d -u ${MD}
>	return 0
>}
>
>main () {
>	if [ "$(id -u)" != "0" ]; then
>		echo "Need to be root (mdconfig, mount)"
>		exit 1
>	fi
>
>	pid=""
>	init_disk_image
>
>	while true; do
>		mount_race 1 &
>		pid=$!
>		mount_race 2
>		wait $pid
>		echo "Failed to trigger it, restarting..."
>	done
>
>	rm /tmp/mount_bug
>}
>
>main

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Attachments on bug 255047: 224098 | 237865