arm开发板采用ubuntu根文件系统自动挂载U盘解决方案升级版!

背景

    之前有一篇文章：《ARM-Linux下实现U盘自动挂载》在嵌入式Linux开发板中实现自动挂载U盘的方法。该方法有效，但局限。本人自己测试是在buildroot构建的根文件系统下实现的，可以识别U盘以及读卡器插SD卡实现U盘方式。
    现在使用瑞芯微RK3288开发板时，却翻车了。
翻车回放：在/etc/udev/rules.d中新建.rules文件,，设置U盘自动挂载路径为/mnt/usb。但是插上U盘后，U盘自动挂载到/media/root目录下。（跑的ubuntu文件系统，自己新建的udev规则无法生效）。目前不知晓修ubuntu文件系统下的哪个文件去更改挂载位置。
解决方法：
一、可用（有缺陷）：
使用systemd-mount、systemd-umount替代mount、umount 亲测有效
直接上解决方案：
1、每次挂载U盘创建挂载文件夹、拔出U盘删除文件夹版本：

vi /etc/udev/rules.d/10-myudisk.rules

添加以下内容：

KERNEL!="sd*", GOTO="media_by_label_auto_mount_end"
SUBSYSTEM!="block",GOTO="media_by_label_auto_mount_end"
IMPORT{program}="/sbin/blkid -o udev -p %N"
ENV{ID_FS_TYPE}=="", GOTO="media_by_label_auto_mount_end"
ENV{ID_FS_LABEL}!="", ENV{dir_name}="%E{ID_FS_LABEL}"
ENV{ID_FS_LABEL}=="", ENV{dir_name}="%E{ID_FS_UUID}"
ACTION=="add", ENV{mount_options}="relatime,sync"
ACTION=="add", ENV{ID_FS_TYPE}=="vfat|ntfs", ENV{mount_options}="iocharset=utf8,umask=000"
ACTION=="add", RUN+="/bin/mkdir -p /media/%E{dir_name}", RUN+="/usr/bin/systemd-mount -o %E{mount_options} --no-block --automount=yes --collect /dev/%k /media/%E{dir_name}"
ACTION=="remove", ENV{dir_name}!="", RUN+="/usr/bin/systemd-mount --umount /media/%E{dir_name}", RUN+="/bin/rmdir /media/%E{dir_name}" 
LABEL="media_by_label_auto_mount_end"

2、直接挂载到固定文件夹版本：

vi /etc/udev/rules.d/10-myudisk.rules

添加以下内容：

KERNEL!="sd*", GOTO="media_by_label_auto_mount_end"
SUBSYSTEM!="block",GOTO="media_by_label_auto_mount_end"
IMPORT{program}="/sbin/blkid -o udev -p %N"
ENV{ID_FS_TYPE}=="", GOTO="media_by_label_auto_mount_end"
ENV{ID_FS_LABEL}!="", ENV{dir_name}="%E{ID_FS_LABEL}"
ENV{ID_FS_LABEL}=="", ENV{dir_name}="%E{ID_FS_UUID}"
ACTION=="add", ENV{mount_options}="relatime,sync"
ACTION=="add", ENV{ID_FS_TYPE}=="vfat", ENV{mount_options}="iocharset=utf8,umask=000"
ACTION=="add", ENV{ID_FS_TYPE}=="ntfs", ENV{mount_options}="iocharset=utf8,umask=000"
ACTION=="add",  RUN+="/usr/bin/systemd-mount -o %E{mount_options} --no-block --automount=yes --collect /dev/%k /home/zml"
ACTION=="remove", ENV{dir_name}!="", RUN+="/usr/bin/systemd-umount --l /home/zml"
LABEL="media_by_label_auto_mount_end"

注意：目前测试在ubuntu文件系统下，只识别纯正的U盘，不识别读卡器插SD卡的伪U盘方式！！！
本人查看了两者属性及其他信息，基本没区别，但是就是不能加载读卡器插sd卡的伪U盘方式，可以识别到/dev/sda /dev/sda1，但是加载不出伪U盘内的文件。但是可以通过手动挂载的方式实现读取SD内的文件！！！

二、可用，无缺陷：
共三步：
step1：
创建脚本文件：

vi /usr/local/bin/usbstorage-mount.sh

添加以下内容：
1、采用创建文件夹、删除文件夹方式：

#!/bin/bash

# This script is called from our systemd unit file to mount or unmount
# a USB drive.

usage()
{
    echo "Usage: $0 {add|remove} device_name (e.g. sdb1)"
    exit 1
}

if [[ $# -ne 2 ]]; then
    usage
fi

ACTION="$1"
DEVBASE="$2"
DEVICE="/dev/${DEVBASE}"

# See if this drive is already mounted, and if so where
MOUNT_POINT=$(/bin/mount | /bin/grep ${DEVICE} | /usr/bin/awk '{ print $3 }')

do_mount()
{
    if [[ -n "${MOUNT_POINT}" ]]; then
        echo "Warning: ${DEVICE} is already mounted at ${MOUNT_POINT}"
        exit 1
    fi

    # Get info for this drive: $ID_FS_LABEL, $ID_FS_UUID, and $ID_FS_TYPE
    # added some sed's to avoid space issues
    eval $(/sbin/blkid -o udev ${DEVICE}|sed 's/=/="/'|sed 's/$/"/')

    # Figure out a mount point to use
    LABEL="${ID_FS_LABEL}"
    if [[ -z "${LABEL}" ]]; then
        LABEL="${DEVBASE}"
    elif /bin/grep -q " /media/${LABEL} " /etc/mtab; then
        # Already in use, make a unique one
        LABEL+="-${DEVBASE}"
    fi
    MOUNT_POINT="/media/${LABEL}"

    echo "Mount point: ${MOUNT_POINT}"

    /bin/mkdir -p "${MOUNT_POINT}"

    # Global mount options
    OPTS="rw,relatime"
    #added a chmod checker for file systems that don't 
    #understand allow all to read write
    # CHMOD=no
    # File system type specific mount options
    if [[ ${ID_FS_TYPE} == "vfat" ]]; then
        OPTS+=",users,gid=100,iocharset=utf8,umask=000"
        # OPTS+=",users,gid=100,umask=000,shortname=mixed,utf8=1,flush"
    #added options I wanted on ntfs
    elif [[ ${ID_FS_TYPE} == "ntfs" ]]; then
        OPTS+=",users,gid=100,iocharset=utf8,umask=000"
        # OPTS+=",user,users,umask=000,allow_other"                      
    else
       OPTS+=",users,gid=100,iocharset=utf8,umask=000"
    #    CHMOD=yes
    fi

    if ! /bin/mount -o "${OPTS}" ${DEVICE} "${MOUNT_POINT}"; then
        echo "Error mounting ${DEVICE} (status = $?)"
        /bin/rmdir "${MOUNT_POINT}"
        exit 1
    fi


    echo "**** Mounted ${DEVICE} at ${MOUNT_POINT} ****"
    # if [ "${CHMOD}" = "yes" ];then
    #     /usr/bin/find "${MOUNT_POINT}" -type f -exec chmod 0666 {} \;
    #     /usr/bin/find "${MOUNT_POINT}" -type d -exec chmod 0777 {} \;
    # fi
}

do_unmount()
{
    if [[ -z ${MOUNT_POINT} ]]; then
        echo "Warning: ${DEVICE} is not mounted"
    else
        /bin/umount -l ${DEVICE}
        echo "**** Unmounted ${DEVICE}"
    fi

    # Delete all empty dirs in /media that aren't being used as mount
    # points. This is kind of overkill, but if the drive was unmounted
    # prior to removal we no longer know its mount point, and we don't
    # want to leave it orphaned...
    for f in /media/* ; do
        if [[ -n $(/usr/bin/find "$f" -maxdepth 0 -type d -empty) ]]; then
            if ! /bin/grep -q " $f " /etc/mtab; then
                echo "**** Removing mount point $f"
                /bin/rmdir "$f"
            fi
        fi
    done
}

case "${ACTION}" in
    add)
        do_mount
        ;;
    remove)
        do_unmount
        ;;
    *)
        usage
        ;;
 esac

2、采用挂载固定文件夹的方式：

#!/bin/bash

# This script is called from our systemd unit file to mount or unmount
# a USB drive.

usage()
{
    echo "Usage: $0 {add|remove} device_name (e.g. sdb1)"
    exit 1
}

if [[ $# -ne 2 ]]; then
    usage
fi

ACTION="$1"
DEVBASE="$2"
DEVICE="/dev/${DEVBASE}"

# See if this drive is already mounted, and if so where
MOUNT_POINT=$(/bin/mount | /bin/grep ${DEVICE} | /usr/bin/awk '{ print $3 }')

do_mount()
{
    if [[ -n "${MOUNT_POINT}" ]]; then
        echo "Warning: ${DEVICE} is already mounted at ${MOUNT_POINT}"
        exit 1
    fi

    # Get info for this drive: $ID_FS_LABEL, $ID_FS_UUID, and $ID_FS_TYPE
    # added some sed's to avoid space issues
    eval $(/sbin/blkid -o udev ${DEVICE}|sed 's/=/="/'|sed 's/$/"/')

    # Figure out a mount point to use
    LABEL="${ID_FS_LABEL}"
    if [[ -z "${LABEL}" ]]; then
        LABEL="${DEVBASE}"
    elif /bin/grep -q "/home/zml/lcdfile" /etc/mtab; then
        # Already in use, make a unique one
        LABEL+="-${DEVBASE}"
    fi
    MOUNT_POINT="/home/zml/lcdfile"

    echo "Mount point: ${MOUNT_POINT}"

    # /bin/mkdir -p "${MOUNT_POINT}"

    # Global mount options
    OPTS="rw,relatime,sync"
    #added a chmod checker for file systems that don't 
    #understand allow all to read write
    # CHMOD=no
    # File system type specific mount options
    if [[ ${ID_FS_TYPE} == "vfat" ]]; then
        OPTS+=",users,gid=100,iocharset=utf8,umask=000"
        # OPTS+=",users,gid=100,umask=000,shortname=mixed,utf8=1,flush"
    #added options I wanted on ntfs
    elif [[ ${ID_FS_TYPE} == "ntfs" ]]; then
        OPTS+=",users,gid=100,iocharset=utf8,umask=000"
        # OPTS+=",user,users,umask=000,allow_other"                      
    else
       OPTS+=",users,gid=100,iocharset=utf8,umask=000"
    #    CHMOD=yes
    fi

    if ! /bin/mount -o "${OPTS}" ${DEVICE} "${MOUNT_POINT}"; then
        echo "Error mounting ${DEVICE} (status = $?)"
        # /bin/rmdir "${MOUNT_POINT}"
        exit 1
    fi


    echo "**** Mounted ${DEVICE} at ${MOUNT_POINT} ****"
    # if [ "${CHMOD}" = "yes" ];then
    #     /usr/bin/find "${MOUNT_POINT}" -type f -exec chmod 0666 {} \;
    #     /usr/bin/find "${MOUNT_POINT}" -type d -exec chmod 0777 {} \;
    # fi
}

do_unmount()
{
    if [[ -z ${MOUNT_POINT} ]]; then
        echo "Warning: ${DEVICE} is not mounted"
    else
        /bin/umount -l ${DEVICE}
        echo "**** Unmounted ${DEVICE}"
    fi

    # Delete all empty dirs in /media that aren't being used as mount
    # points. This is kind of overkill, but if the drive was unmounted
    # prior to removal we no longer know its mount point, and we don't
    # want to leave it orphaned...

    # for f in /media/* ; do
    #     if [[ -n $(/usr/bin/find "$f" -maxdepth 0 -type d -empty) ]]; then
    #         if ! /bin/grep -q " $f " /etc/mtab; then
    #             echo "**** Removing mount point $f"
    #             /bin/rmdir "$f"
    #         fi
    #     fi
    # done
}

case "${ACTION}" in
    add)
        do_mount
        ;;
    remove)
        do_unmount
        ;;
    *)
        usage
        ;;
esac

以上方式根据自己需求选择其一即可。
创建完脚本，需要赋上可执行权限

chmod a+x /usr/local/bin/usbstorage-mount.sh

step2:

vi /lib/systemd/system/usb-mount@.service

添加以下内容：

[Unit]
Description=Mount USB Drive on %i

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/usr/local/bin/usbstorage-mount.sh add %i
ExecStop=/usr/local/bin/usbstorage-mount.sh remove %i

step3：
创建udev规则：

vi /etc/udev/rules.d/10-myusbstorage.rules

添加以下内容：

KERNEL!="sd*", GOTO="auto_mount_end"
SUBSYSTEM!="block", GOTO="auto_mount_end"
ACTION=="add", RUN+="/bin/systemctl start usb-mount@%k.service"
ACTION=="remove", RUN+="/bin/systemctl stop usb-mount@%k.service"
LABEL="auto_mount_end"

完成以上三步，可以选择重启开发板，或者执行以下命令，即可实现全部功能：

# 重新加载 udev rules 文件
udevadm control --reload-rules
# 重新加载 systemd unit 文件
systemctl daemon-reload

参考文章：（可能需要）
https://serverfault.com/questions/766506/automount-usb-drives-with-systemd