From: Herbert Xu <herbert@gondor.apana.org.au>
Subject: Re: [PATCH v2 0/4] Introduce bulk mode for crypto engine framework
Date: Mon, 18 Apr 2016 16:31:16 +0800
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Cc: David Miller <davem@davemloft.net>,
	Alasdair G Kergon <agk@redhat.com>,
	Mike Snitzer <snitzer@redhat.com>, Jens Axboe <axboe@fb.com>,
	dm-devel@redhat.com, Andrew Morton <akpm@linux-foundation.org>,
	david.s.gordon@intel.com, Tom Lendacky <thomas.lendacky@amd.com>,
	Robert Jarzmik <robert.jarzmik@free.fr>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	smueller@chronox.de, tadeusz.struk@intel.com,
	Masanari Iida <standby24x7@gmail.com>, shli@kernel.org,
	Mark Brown <broonie@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-crypto@vger.kernel.org, linux-raid@vger.kernel.org
To: Baolin Wang <baolin.wang@linaro.org>
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On Mon, Apr 18, 2016 at 04:28:46PM +0800, Baolin Wang wrote:
> 
> What I meaning is if the xts engine can support bulk block, then the
> engine driver can select bulk mode to do encryption, but if their xts
> engine can not support bulk mode, which depends on hardware design,
> the engine driver can not select bulk mode. So the dm-crypt can not
> know what will be selected by the engine driver, it can not send one
> bulk block each time.

Why can't the xts code just break it up if it can't handle it?

You want to postpone splitting as much as possible.  Even if the
underlying xts code couldn't handle it, it would still make sense
for the crypto API to see the request in one piece.

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