OpenWrt 挂载 USB 存储设置 exroot

opkg update
opkg install block-mount kmod-usb-storage kmod-fs-ext4
reboot

mkdir /mnt/usb
mount -t ext4 /dev/sda1 /mnt/usb

config 'global'
option  anon_swap   '0'
option  anon_mount  '0'
option  auto_swap   '1'
option  auto_mount  '1'
option  delay_root  '5'
option  check_fs    '0'

config 'mount'
option  target  '/'
option  device  /dev/sda1
option  enabled '1'
option  fstype  ext4
option  options rw,sync
option  enabled_fsck    0

mkdir /tmp/cproot
mount --bind / /tmp/cproot
tar -C /tmp/cproot -cvf - . | tar -C /mnt/usb -xvf -
sync ; umount /mnt/usb
umount /tmp/cproot