ubi resize shrink volume

[Jaap de Jong]

On 18-09-17 09:06, Richard Weinberger wrote:
> Am Montag, 18. September 2017, 08:34:34 CEST schrieb Jaap de Jong:
>> On 15-09-17 20:30, Richard Weinberger wrote:
>>> On Fri, Sep 15, 2017 at 8:34 AM, Jaap de Jong <jaap.dejong at nedap.com> wrote:
>>>> Hi All!
>>>>
>>>> I've seen a several (old) posts regarding this subject and I was
>>>> wondering
>>>> what the status at this moment is.
>>>>
>>>> Is there any implementation available that is able to shrink a ubi
>>>> volume,
>>>> so that it will move used blocks at the end to the front?
>>> Not sure if I got your use case, but you can do this in userspace.
>>>
>>> If you're asking whether it is possible to shrink UBIFS, no, this is
>>> not possible.
>> Sorry for the confusion.
>> Yes, I want to shrink of a not-mounted UBIFS preferably in u-boot.
>> In the posts I read it should not be that hard to do, so I was wondering
>> if anyone had taken the effort to implement this...
> Nope. So far nobody cared enough about this feature.
> Please note that many other major filesystems alos don't support this.
> Such das XFS.
>
Well we do care!
Any thoughts to share? We could use some help...
My first impression was that the size of the partition was just a 
maximum number of PEBs to use for it,
so lowering that value would just set a new limit and whatever PEBs were 
used for that specific partition
was under control of the wear-levelling algorithms. But apparently it is 
more complicated.