usb disk

1.mount

/dev/block/vold/179:22 /storage/sdcard0 vfat rw,dirsync,nosuid,nodev,noexec,relatime,uid=1000,gid=1015,fmask=0002,dmask=0002,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0

/dev/block/vold/179:22 /mnt/secure/asec vfat rw,dirsync,nosuid,nodev,noexec,relatime,uid=1000,gid=1015,fmask=0002,dmask=0002,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0

2. set mass_storage

3.echo /dev/block/vold/179:22>sys/class/android_usb/android0/f_mass_storage/lun/file