From: Herbert Xu <herbert@gondor.apana.org.au>
To: Baolin Wang <baolin.wang@linaro.org>
Cc: Jens Axboe <axboe@kernel.dk>, Alasdair G Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@redhat.com>,
"open list:DEVICE-MAPPER (LVM)" <dm-devel@redhat.com>,
David Miller <davem@davemloft.net>,
Eric Biggers <ebiggers3@gmail.com>,
Joonsoo Kim <js1304@gmail.com>,
tadeusz.struk@intel.com, smueller@chronox.de,
Masanari Iida <standby24x7@gmail.com>,
Shaohua Li <shli@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Sagi Grimberg <sagig@mellanox.com>,
Kent Overstreet <kent.overstreet@gmail.com>,
Keith Busch <keith.busch@intel.com>, Tejun Heo <tj@kernel.org>,
Ming Lei <ming.lei@canonical.com>,
Mark Brown <broonie@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
linux-crypto@vger.kernel.org, linux-block@vger.kernel.org,
"open list:SOFTWARE RAID (Multiple Disks) SUPPORT"
<linux-raid@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC v4 2/4] crypto: Introduce CRYPTO_ALG_BULK flag
Date: Wed, 15 Jun 2016 14:49:40 +0800 [thread overview]
Message-ID: <20160615064939.GA14227@gondor.apana.org.au> (raw)
In-Reply-To: <CAMz4kuKXJ5xUXj111VBb9hMH=kT3Y5P3_iVtgeS8kidbLZ+6TA@mail.gmail.com>
On Wed, Jun 15, 2016 at 02:27:04PM +0800, Baolin Wang wrote:
>
> After some investigation, I still think we should divide the bulk
> request from dm-crypt into small request (each one is 512bytes) if
> this algorithm is not support bulk mode (like CBC). We have talked
> with dm-crypt
> maintainers why dm-crypt always use 512 bytes as one request size in
> below thread, could you please check it?
> http://www.kernelhub.org/?p=2&msg=907022
That link only points to an email about an oops.
Diggin through that thread, the only objection I have seen is about
the fact that you have to generate a fresh IV for each sector, which
is precisely what I'm suggesting that you do.
IOW, implement the IV generators in the crypto API, and then you can
easily generate a new IV (if necessary) for each sector.
> That means if we move the IV handling into crypto API, we still can
> not use bulk interface for all algorithm, for example we still need to
> read/write with 512 bytes for CBC, you can't use 4k or more block on
> CBC (and most other encryption modes). If only a part of 4k block is
> written (and then system crash happens), CBC would corrupt the block
> completely. It means if we map one whole bio with bulk interface in
> dm-crypt, we need to divide into every 512 bytes requests in crypto
> layer. So I don't think we can handle every algorithm with bulk
> interface just moving the IV handling into crypto API. Thanks.
Of course you would do CBC in 512-byte blocks, but my point is that
you should do this in a crypto API algorithm, rather than dm-crypt
as we do now. Once you implement that then dm-crypt can treat
every algorithm as if they supported bulk processing.
Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2016-06-15 6:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-07 12:17 [RFC v4 0/4] Introduce the bulk mode method when sending request to crypto layer Baolin Wang
2016-06-07 12:17 ` [RFC v4 1/4] block: Introduce blk_bio_map_sg() to map one bio Baolin Wang
2016-06-07 12:17 ` [RFC v4 2/4] crypto: Introduce CRYPTO_ALG_BULK flag Baolin Wang
2016-06-07 14:16 ` Herbert Xu
2016-06-08 2:00 ` Baolin Wang
2016-06-15 6:27 ` Baolin Wang
2016-06-15 6:49 ` Herbert Xu [this message]
2016-06-15 7:38 ` Baolin Wang
2016-06-15 7:39 ` Herbert Xu
2016-06-15 8:48 ` Baolin Wang
2016-06-07 12:17 ` [RFC v4 3/4] md: dm-crypt: Introduce the bulk mode method when sending request Baolin Wang
2016-06-07 12:17 ` [RFC v4 4/4] crypto: Add the CRYPTO_ALG_BULK flag for ecb(aes) cipher Baolin Wang
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