[dm-devel] dm-verity: Verification fails but do not see Input/Output Error on read
Mikulas Patocka
mpatocka at redhat.com
Thu Aug 8 12:52:21 UTC 2013
On Thu, 8 Aug 2013, Chaitra Bhat wrote:
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> Hi Alasdair,
>
> Thanks for your response.
>
> But I am not convinced. Here is why...
>
> 1. I tried a bit-more and I was able to get Input/Output Error on
> certain locations - everytime - I read that location. (But I still have
> an open question that on some locations, though the verify reports
> failure, I do not get an IO Error on read)
>
> 2. I do not understand when you say device is live - do you mean
> mounted? Because I thought that the whole idea of dm-verity was that
> once the verity device is set-up, it would return EIO when something
> gets corrupted in the data or hash partitions when that invalid data is
> read.
>
> Chaitra
It is possible that you are reading data from the buffer cache and not
from the underlying device.
To not use the buffer cache, use iflag=direct parameter to dd.
Mikulas
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