Each ace master high master, everybody is good, I have an android 4.4.2 car machine, has been the root, I was installed on the car navigation software, because the machine built-in storage space is 6.3 G, the relatively small, and the system of the external USB drive only support Fat32 format, was the mount at/storage/otg the directory, and navigation software can't write data to an external USB drive, will you ask is there any way can be simulated the USB drive into the built-in SD card, or mount this directory under the/storage/sdcard? Record have fstab file system root, but the/partition is read-only, can't change, tried to use the adb command shell sm, but do not support sm, system also cannot use fdisk, please action, is there any way, thank you!

The root directory is as follows:

 root @ garmin89_tb_ali_kk:/# ls - la 
Ls - la 
DRWXR xr - x root root 2019-08-12 09:48 acct 
DRWXRWX - system cache the 2019-08-12 probably cache 
Dr X -- -- -- -- -- -- root root 2019-08-12 09:48 config 
DRWXR xr - x root root 2019-08-12 09:48 custom 
LRWXRWXRWX root root 09:48 d - 2019-08-12 & gt;/sys/kernel/debug 
DRWXRWX - system system x 2019-08-12 11:07 data 
Rw - r - r - 233 1970-01-01 root root 08:00 default. The prop 
DRWXR xr - x root root 2019-08-14 did dev 
LRWXRWXRWX root root 1970-01-01 08:00 emmc @ android - & gt;/dev/block/mmcblk0p5 
LRWXRWXRWX root root 1970-01-01 08:00 emmc @ cache - & gt;/dev/block/mmcblk0p6 
Rw - r - r - root root 0 2019-08-12 09:48 emmc @ custom 
LRWXRWXRWX root root 1970-01-01 08:00 emmc @ ebr1 - & gt;/dev/block/mmcblk0p1 
LRWXRWXRWX root root 1970-01-01 08:00 emmc @ protect_f - & gt;/dev/block/mmcblk0p2 
LRWXRWXRWX root root 1970-01-01 08:00 emmc @ protect_s - & gt;/dev/block/mmcblk0p3 
LRWXRWXRWX root root 1970-01-01 08:00 emmc @ sec_ro - & gt;/dev/block/mmcblk0p4 
LRWXRWXRWX root root 1970-01-01 08:00 emmc @ usrdata - & gt;/dev/block/mmcblk0p7 
Rw - r - r - 127 1970-01-01 root root 08:00 enableswap. Sh 
LRWXRWXRWX root root 09:48 etc - 2019-08-12 & gt;/system/etc 
Rw - r - r - 2204 1970-01-01 root root 08:00 factory_init. Project. Rc 
Rw - r - r - 11620 1970-01-01 root root 08:00 factory_init. Rc 
Rw - r - r - 27418 root root 1970-01-01 08:00 file_contexts 
Rw - r - r - 929 root root 1970-01-01 08:00 fstab 
Rw - r -- -- -- -- -- root root 929 1970-01-01 08:00 fstab. Fat. Nand 
Rw - r -- -- -- -- -- root root 929 1970-01-01 08:00 fstab. Nand 
- RWXR - x - 220840 1970-01-01 root root 08:00 init 
- RWXR - x - 1123 1970-01-01 root root 08:00 init. Environ. Rc 
- RWXR - x - root root 0 1970-01-01 08:00 init. Modem. Rc 
- RWXR - x - 10670 1970-01-01 root root 08:00 init. Rc 
 project.- RWXR - x - 969 1970-01-01 root root 08:00 init. Protect. Rc 
- RWXR - x - 48194 1970-01-01 root root 08:00 init. Rc 
- RWXR - x - 1829 1970-01-01 root root 08:00 init. SSD. Rc 
- RWXR - x - 2126 1970-01-01 root root 08:00 init. Trace. Rc 
- RWXR - x - 20881 1970-01-01 root root 08:00 init. Usb. Rc 
- RWXR - x - 583 1970-01-01 root root 08:00 init. Xlog. Rc 
Rw - r - r - root root 0 1970-01-01 08:00 meta_init. Modem. Rc 
Rw - r - r - 2371 1970-01-01 root root 08:00 meta_init. Project. Rc 
Rw - r - r - 10339 1970-01-01 root root 08:00 meta_init. Rc 
DRWXRWXR - root system x 2019-08-12 09:48 MNT 
Dr - xr - xr - x root root 1970-01-01 08:00 proc 
Rw - r - r - 2209 root root 1970-01-01 08:00 property_contexts 
DRWXRWX - system system x 2010-01-01 08:00 protect_f 
DRWXRWX - system system x 2019-08-11 15:43 protect_s 
DRWX -- -- -- -- -- - root root 2015-07-27 12:57 root 
DRWXR - x - nvram system 1970-01-01 08:00 SBCHK 
DRWXR - x - root root 1970-01-01 08:00 sbin 
LRWXRWXRWX root root 2019-08-12 09:48 sdcard - & gt;/storage/emulated/legacy 
Rw - r - r - 736 root root 1970-01-01 08:00 seapp_contexts 
Rw - r - r - 235709 root root 1970-01-01 08:00 sepolicy 
DRWXR - x - x root sdcard_r 2019-08-12 09:48 storage 
Dr - xr - xr - x root root 2019-08-12 09:48 sys 
DRWXR xr - x root root system lie 2019-08-14 
Rw - r - r - 6840 1970-01-01 root root 08:00 ueventd. Rc 
LRWXRWXRWX root root 2019-08-12 09:48 vendor - & gt;/system/vendor 
Root @ garmin89_tb_ali_kk:/#