[dm-devel] dm-integrity: integrity protection device-mapper target

[Alasdair G Kergon]

On Fri, Jan 18, 2013 at 11:43:34PM +0200, Kasatkin, Dmitry wrote:
> This patch I sent out has one missing feature what I have not pushed yet.
> In the case of non-matching blocks, it just zeros blocks and returns
> no error (zero-on-mismatch).
> Writing to the block replaces the hmac.
> It works quite nicely. mkfs and fsck is able to read and write/fix the
> filesystem.
> In normal environment, if fsck crashes, it might corrupt file system
> in the same way.
> zero-on-mismatch makes block device still accessible/fixable for fsck.
 
I'm afraid I don't buy that.

We can hardly call this "integrity" if it's designed to lose some of
your data when the machine crashes - and worse - it doesn't tell you
what you lost, but just gives you blocks of zeroes instead!

I think a redesign is needed before this goes upstream.

Alasdair