Re: LZO irreversible output?

From: Rafael J. Wysocki
Date: Wed Feb 03 2010 - 17:53:38 EST


On Wednesday 03 February 2010, Nigel Cunningham wrote:
> Hi all.
>
> (Not sent to LKML yesterday; no reply from linux-crypto yet, so resending).
>
> A while back now, I stopped supplying the LZF compression algorithm with
> TuxOnIce and made LZO the default algorithm. Around the same time, we
> started getting occasional errors when reading images; decompression
> failures.
>
> I've finally managed to find the time to properly look at this, and have
> managed to find a data page that LZO compresses, but seems to be unable
> to decompress back to the original contents. I'm wondering whether this
> is because I'm doing something wrong, or because there really is some
> data the LZO (or the kernel implementation) can't do reversible
> compression on.

Well, FWIW, we have never had any problems with the userland LZO in s2disk,
so if anything is wrong with LZO here, I guess it's the kernel code.

Rafael
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