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Subject: Re: [PATCH 5/5] ubi: Allow to use read-only UBI volume with not
 enough PEBs
To: =?UTF-8?Q?Pali_Roh=c3=a1r?= <pali.rohar@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
        Brian Norris <computersforpeace@gmail.com>,
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 <20170725142729.GL30901@pali>
From: Richard Weinberger <richard@nod.at>
Message-ID: <0527d020-95aa-80e5-978c-fa9b6761a273@nod.at>
Date: Sun, 6 Aug 2017 11:43:25 +0200
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Pali,

Am 25.07.2017 um 16:27 schrieb Pali Rohár:
>> I fear this is not correct, it will disable a legit self-check of UBI volumes.
>> If the read-only volume is corrupted/truncated and you miss PEBs, this
>> check will no longer
>> trigger.
>>
>> Especially when dealing with nanddumps, truncation is a common problem.
> 
> Any idea how to fix it? Or how to handle read-only images which are
> marked for auto-resize?

I'd vote for rejecting images that have auto-resize set when the MTD is read-only.
In fact, using UBI on top of a read-only MTD is very uncommon and not recommended (for NAND).
The auto-resize flag should be also only set when you just have created it using mkfs.ubifs.
Why would you inspect such an image with the kernel UBIFS unless you're hunting down a bug
in mkfs.ubifs?

Thanks,
//richard