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([91.90.172.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-acaa1ce72f5sm1058794966b.173.2025.04.15.00.42.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Apr 2025 00:42:56 -0700 (PDT) From: Daniel Semkowicz To: openembedded-core@lists.openembedded.org Cc: Daniel Semkowicz Subject: [PATCH v1] udev/udev-extraconf: Fix race in automount cache Date: Tue, 15 Apr 2025 09:42:11 +0200 Message-ID: <20250415074212.2559315-1-dse@thaumatec.com> X-Mailer: git-send-email 2.49.0 MIME-Version: 1.0 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Tue, 15 Apr 2025 07:43:02 -0000 X-Groupsio-URL: https://lists.openembedded.org/g/openembedded-core/message/214826 Cache files with names of automounted devices were saved in /tmp directory, but base directories for mount points are created by default in the /run/media directory. With systemd init manager, /tmp is mounted by the systemd service. Udev has no dependency on /tmp and this creates a race condition. It is possible that the block device is already present in the device and the udev rules for automount are triggered during boot before /tmp is mounted. In such a case, mount cache files are created on the base file system. If the base file system is read-write, the cached file persists after the reboot and prevents automount on the next boot. Use the mount base directory for storing cache files. Both mount points and cache will be created in the same place, so there will be no race. Signed-off-by: Daniel Semkowicz --- meta/recipes-core/udev/udev-extraconf/mount.sh | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/meta/recipes-core/udev/udev-extraconf/mount.sh b/meta/recipes-core/udev/udev-extraconf/mount.sh index 0cbae48729..467703daa4 100644 --- a/meta/recipes-core/udev/udev-extraconf/mount.sh +++ b/meta/recipes-core/udev/udev-extraconf/mount.sh @@ -7,6 +7,7 @@ BASE_INIT="`readlink -f "@base_sbindir@/init"`" INIT_SYSTEMD="@systemd_unitdir@/systemd" MOUNT_BASE="@MOUNT_BASE@" +AUTOMOUNT_CACHE_DIR="${MOUNT_BASE}/.automount" if [ "x$BASE_INIT" = "x$INIT_SYSTEMD" ];then # systemd as init uses systemd-mount to mount block devices @@ -60,7 +61,7 @@ automount_systemd() { # Only go for auto-mounting when the device has been cleaned up in remove # or has not been identified yet - if [ -e "/tmp/.automount-$name" ]; then + if [ -e "${AUTOMOUNT_CACHE_DIR}/$name" ]; then logger "mount.sh/automount" "[$MOUNT_BASE/$name] is already cached" return fi @@ -104,7 +105,8 @@ automount_systemd() { rm_dir "$MOUNT_BASE/$name" else logger "mount.sh/automount" "Auto-mount of [$MOUNT_BASE/$name] successful" - echo "$name" > "/tmp/.automount-$name" + [ -d "${AUTOMOUNT_CACHE_DIR}" ] || mkdir "${AUTOMOUNT_CACHE_DIR}" + echo "$name" > "${AUTOMOUNT_CACHE_DIR}/$name" fi } @@ -126,7 +128,7 @@ automount() { # Only go for auto-mounting when the device has been cleaned up in remove # or has not been identified yet - if [ -e "/tmp/.automount-$name" ]; then + if [ -e "${AUTOMOUNT_CACHE_DIR}/$name" ]; then logger "mount.sh/automount" "[$MOUNT_BASE/$name] is already cached" return fi @@ -162,10 +164,11 @@ automount() { # The actual device might not be present in the remove event so blkid cannot # be used to calculate what name was generated here. Simply save the mount # name in our tmp file. - echo "$name" > "/tmp/.automount-$name" + [ -d "${AUTOMOUNT_CACHE_DIR}" ] || mkdir "${AUTOMOUNT_CACHE_DIR}" + echo "$name" > "${AUTOMOUNT_CACHE_DIR}/$name" fi } - + rm_dir() { # We do not want to rm -r populated directories if test "`find "$1" | wc -l | tr -d " "`" -lt 2 -a -d "$1" @@ -206,7 +209,7 @@ fi if [ "$ACTION" = "remove" ] || [ "$ACTION" = "change" ] && [ -x "$UMOUNT" ] && [ -n "$DEVNAME" ]; then name="`basename "$DEVNAME"`" - tmpfile=`find /tmp | grep "\.automount-.*${name}$"` + tmpfile=`find "${AUTOMOUNT_CACHE_DIR}" -name "*${name}"` if [ ! -e "/sys/$DEVPATH" -a -e "$tmpfile" ]; then logger "mount.sh/remove" "cleaning up $DEVNAME, was mounted by the auto-mounter" for mnt in `cat /proc/mounts | grep "$DEVNAME" | cut -f 2 -d " " `