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Date: Thu, 14 May 2015 09:58:48 +0200
From: Richard Weinberger <richard@nod.at>
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To: Sheng Yong <shengyong1@huawei.com>,
 Michael Niarchos <michael.niarchos@gmail.com>
Subject: Re: Cannot mount ubifs partition
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Am 14.05.2015 um 05:45 schrieb Sheng Yong:
> Hi, folks,
> 
> On 5/13/2015 5:20 PM, Richard Weinberger wrote:
>> Am 13.05.2015 um 11:06 schrieb Michael Niarchos:
>>>
>>>
>>> On 05/13/2015 11:59 AM, Richard Weinberger wrote:
>>>> Am 13.05.2015 um 10:56 schrieb Michael Niarchos:
>>>>> Volume ID:   0 (on ubi0)
>>>>> Type:        dynamic
>>>>> Alignment:   1
>>>>> Size:        3964 LEBs (503332864 bytes, 480.0 MiB)
>>>>> State:       OK
>>>>> Name:        ubi-rootfs
>>>>> Character device major/minor: 246:1
>>>>
>>>> Is the device node present?
>>>>
>>>> Thanks,
>>>> //richard
>>>>
>>> Yes, it is present
>>>
>>> root@zx3-pm3-zynq7:~# find /dev -name "ubi*"
>>> /dev/ubi0_0
>>> /dev/ubi0
>>> /dev/ubi_ctrl
>>
>> BTW: Have you created the nodes by hand? Do major/minor numbers match?

Michael's problem was that ubifs was not loaded.
He confirmed that off-list.

> If we create the dev node by hand, it is hard for kernel to notice that.
> 
> UBI (and even driver base) seems doesn't know and doesn't care if device
> nodes already exist. UBI just checks the ubi_devices, registers devices,
> and tells udev to make node. Although everything seems ok, `mount' will
> fail because of wrong device node. However, the "device node" is removed
> when detaching without any warning or error message. In this way, UBI
> could delete the file without user's permission.
> 
> Is this appropriate? Shall we add some code in ubidetach to detect whether
> the "device node" to be removed is correct?

Isn't this the behavior that all device drivers have?
Maybe I miss something as my uptime is less than 15min. ;)

Thanks,
//richard