UBIFS assert when rebooting a read only ubifs when it's been remounted r/w

[Martin Townsend]

On Tue, May 17, 2016 at 5:13 PM, Richard Weinberger
<richard.weinberger at gmail.com> wrote:
> On Tue, May 17, 2016 at 5:19 PM, Martin Townsend
> <mtownsend1973 at gmail.com> wrote:
>> Hi,
>>
>> I've just seen the following UBIFS assert which relates to
>> ubifs_remount_fs in fs/ubifs/super.c
>> We have a read only root filesystem and it looks like this problem
>> occurs after rebooting the board when the root filesystem has been
>> remounted as as r/w, I use the following command to do this in case
>> I'm doing this incorrectly.
>> mount -o remount,rw /
>> The only way to stop it is to login and run
>> mount -o remount,rw /
>> mount -o remount,ro /
>> and then reboots do not assert.
>>
>> I've tried a few times now and can happily reproduce it.
>>
>> Any ideas on how to fix this?
>
> Let's analyze the root cause first.
> Can you please reproduce with the attached debug patch applied?
> I wonder what the value of c->lst.taken_empty_lebs is.
>
> --
> Thanks,
> //richard

Here's the output
[    3.185429] UBIFS error (ubi0:0 pid 106): ubifs_remount_fs:
taken_empty_lebs is 0

A bit info:
I booted the board over the network using TFTP/NFS and then mounting
the UBIFS partition using
ubiattach /dev/ubi_ctrl -m 12 -O 2048
mount -o ro -t ubifs /dev/ubi0_0 /mnt/ubifs/
but this never triggered the assert. So I thought maybe it was
something to do with U-Boot mounting the rootfs to load the kernel and
device tree which are in the UBIFS so I loaded the kernel and device
tree from a TFTP server and then booted from NAND but this still
triggered the assert so this kind of rules out U-Boot.

-Martin