ubifs image file confusion!

[Nancy]

Hi Artem,
       ubifs.img (generated by mkfs.ubifs) do contained unmapped LEBs.
       #ubiupdatevol /dev/ubi0_0 ubifs.img   also write the unmapped
LEBs to Nand flash.
       Oh, There should have the same problem like I use nandwrite to
write UBI image to Nand. But the practice tells everything is OK.
Maybe during my test, do not touch the unmapped LEBs. But....weird,
should be have the same problem.

   1,
       when I do
       #ubiupdatevol /dev/ubi0_0 ubifs.img
       #mount -t ubifs ubi0:ubifs /mnt/1
       #rm /mnt/1/* -rf
       #df
       The  ubi0:ubifs Use% is not 0%, but 1%

       But,
       #ubiupdatevol /dev/ubi0_0 ubifs.img -t
       #mount -t ubifs ubi0:ubifs /mnt/1
       #cp data ........
       #umount /mnt/1
       #mount -t ubifs ubi0:ubifs /mnt/1
       #rm /mnt/1/* -rf
       #df
       The ubi0:ubifs Use% is 0%, correct!

       Maybe is the ubiupdatevol write unmapped LEB caused!

    2,
       When I want to earse a volume, I can not do
       #ubiupdatevol /dev/ubi0_0 -t     As what the ubiuptodate -h
Example 2 shows
       ubiupdatevol: error!: specify UBI device name and image file
name as first 2 par
ameters (use -h for help)
       but
       #ubiupdatevol /dev/ubi0_0 ubifs.img -t
       instead, even the function do not need an input image file


-- 
Best wishes,
Nancy