Re: [PATCH v4 1/3] udev-extraconf/mount.sh: add support to systemd

["Martin Hundebøll" <martin@geanix.com>]

Hi Hongzhi,

I think duplicating all of 'automount' when the only difference is the 
call to 'mount' is unnecessary.

It should be possible to check for system inside the existing 
'automount' (see diff below).

When reading the script I couldn't help cleaning up the special 
treatment of mount from util-linux (busybox accepts '-o silent' too), 
and remove the 'rm_dir' function, which can be replaced by 'rmdir'.

// Martin

diff --git a/meta/recipes-core/udev/udev-extraconf/mount.sh 
b/meta/recipes-core/udev/udev-extraconf/mount.sh
index d760328a09..6f013c5afb 100644
--- a/meta/recipes-core/udev/udev-extraconf/mount.sh
+++ b/meta/recipes-core/udev/udev-extraconf/mount.sh
@@ -20,11 +20,12 @@ done
  automount() {	
  	name="`basename "$DEVNAME"`"

-	! test -d "/run/media/$name" && mkdir -p "/run/media/$name"
-	# Silent util-linux's version of mounting auto
-	if [ "x`readlink $MOUNT`" = "x/bin/mount.util-linux" ] ;
+	mkdir -p "/run/media/$name"
+
+	# Use systemd-mount to avoid being trapped in udev's mount-namespace
+	if [ "$(readlink /sbin/init)" = "/lib/systemd/systemd" ];
  	then
-		MOUNT="$MOUNT -o silent"
+		MOUNT="/usr/bin/systemd-mount --no-block"
  	fi
  	
  	# If filesystem type is vfat, change the ownership group to 'disk', and
@@ -41,22 +42,12 @@ automount() {
  	if ! $MOUNT -t auto $DEVNAME "/run/media/$name"
  	then
  		#logger "mount.sh/automount" "$MOUNT -t auto $DEVNAME 
\"/run/media/$name\" failed!"
-		rm_dir "/run/media/$name"
+		rmdir "/run/media/$name"
  	else
  		logger "mount.sh/automount" "Auto-mount of [/run/media/$name] 
successful"
  		touch "/tmp/.automount-$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"
-	then
-		! test -z "$1" && rm -r "$1"
-	else
-		logger "mount.sh/automount" "Not removing non-empty directory [$1]"
-	fi
-}

  # No ID_FS_TYPE for cdrom device, yet it should be mounted
  name="`basename "$DEVNAME"`"

On 2018-08-02 04:50, Hongzhi.Song wrote:
> Udev-extraconf works correctly with sysvinit in the aspect of automounting
> block devices. But it has a serious problem in case of systemd. Block devices
> automounted by udev is unaccessible to host space(out of udevd's private
> namespace). For example, we cannot format those block devices.
> 
> e.g.
>      root@qemux86:~# mkfs.ext4 /dev/sda1
>      mke2fs 1.43.8
>      /dev/sda1 contains a ext4 file system
>      last mounted on Tue Apr
>      Proceed anyway? (y,N) y
>      /dev/sda1 is apparently in use by the system; will not make a filesystem here!
> 
> Other distributions has no such problem, because they use a series of rules to
> manager block devices. Different types of block devices match different rules.
> But udev-extraconf just use one rule, automount.rules, which results in this
> problem.
> 
> The 'systemd-mount' command is recommended by the systemd community to solve such
> problems.
> 
> This patch makes use of 'systemd-mount' to solve the above problem.
> 
> [YOCTO #12644]
> 
> Signed-off-by: Hongzhi.Song <hongzhi.song@windriver.com>
> ---
>   meta/recipes-core/udev/udev-extraconf/mount.sh | 55 +++++++++++++++++++++++---
>   1 file changed, 50 insertions(+), 5 deletions(-)
> 
> diff --git a/meta/recipes-core/udev/udev-extraconf/mount.sh b/meta/recipes-core/udev/udev-extraconf/mount.sh
> index d760328a09..3a72c455e0 100644
> --- a/meta/recipes-core/udev/udev-extraconf/mount.sh
> +++ b/meta/recipes-core/udev/udev-extraconf/mount.sh
> @@ -4,10 +4,26 @@
>   #
>   # Attempt to mount any added block devices and umount any removed devices
>   
> +BASE_INIT="`readlink "/sbin/init"`"
> +INIT_SYSTEMD="/lib/systemd/systemd"
> +
> +if [ "x$BASE_INIT" = "x$INIT_SYSTEMD" ];then
> +        MOUNT="/usr/bin/systemd-mount"
> +        UMOUNT="/usr/bin/systemd-umount"
> +
> +        if [ -x $MOUNT ] && [ -x $UMOUNT ];
> +        then
> +                logger "Using systemd-mount to finish mount"
> +        else
> +                logger "Linux init is using systemd, so please install systemd-mount to finish mount"
> +        fi
> +else
> +        MOUNT="/bin/mount"
> +        UMOUNT="/bin/umount"
> +fi
>   
> -MOUNT="/bin/mount"
>   PMOUNT="/usr/bin/pmount"
> -UMOUNT="/bin/umount"
> +
>   for line in `grep -h -v ^# /etc/udev/mount.blacklist /etc/udev/mount.blacklist.d/*`
>   do
>   	if [ ` expr match "$DEVNAME" "$line" ` -gt 0 ];
> @@ -17,6 +33,33 @@ do
>   	fi
>   done
>   
> +automount_systemd() {
> +	name="`basename "$DEVNAME"`"
> +
> +        ! test -d "/run/media/$name" && mkdir -p "/run/media/$name"
> +        # Silent util-linux's version of mounting auto
> +        MOUNT="$MOUNT -o silent"
> +
> +        # If filesystem type is vfat, change the ownership group to 'disk', and
> +        # grant it with  w/r/x permissions.
> +        case $ID_FS_TYPE in
> +        vfat|fat)
> +                MOUNT="$MOUNT -o umask=007,gid=`awk -F':' '/^disk/{print $3}' /etc/group`"
> +                ;;
> +        # TODO
> +        *)
> +                ;;
> +        esac
> +
> +        if ! $MOUNT --no-block -t auto $DEVNAME "/run/media/$name"
> +        then
> +                rm_dir "/run/media/$name"
> +        else
> +                logger "mount.sh/automount" "systemd-mount of [/run/media/$name] successful"
> +                touch "/tmp/.automount-$name"
> +        fi
> +}
> +
>   automount() {	
>   	name="`basename "$DEVNAME"`"
>   
> @@ -61,19 +104,21 @@ rm_dir() {
>   # No ID_FS_TYPE for cdrom device, yet it should be mounted
>   name="`basename "$DEVNAME"`"
>   [ -e /sys/block/$name/device/media ] && media_type=`cat /sys/block/$name/device/media`
> -
>   if [ "$ACTION" = "add" ] && [ -n "$DEVNAME" ] && [ -n "$ID_FS_TYPE" -o "$media_type" = "cdrom" ]; then
>   	if [ -x "$PMOUNT" ]; then
>   		$PMOUNT $DEVNAME 2> /dev/null
>   	elif [ -x $MOUNT ]; then
>       		$MOUNT $DEVNAME 2> /dev/null
>   	fi
> -	
>   	# If the device isn't mounted at this point, it isn't
>   	# configured in fstab (note the root filesystem can show up as
>   	# /dev/root in /proc/mounts, so check the device number too)
>   	if expr $MAJOR "*" 256 + $MINOR != `stat -c %d /`; then
> -		grep -q "^$DEVNAME " /proc/mounts || automount
> +		if [ "`basename $MOUNT`" = "systemd-mount" ];then
> +			grep -q "^$DEVNAME " /proc/mounts || automount_systemd
> +		else
> +			grep -q "^$DEVNAME " /proc/mounts || automount
> +		fi
>   	fi
>   fi
>   
>