Hi Herbert, On 8 June 2016 at 10:00, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote: > Hi Herbert, > > On 7 June 2016 at 22:16, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: >> On Tue, Jun 07, 2016 at 08:17:05PM +0800, Baolin Wang wrote: >>> Now some cipher hardware engines prefer to handle bulk block rather than one >>> sector (512 bytes) created by dm-crypt, cause these cipher engines can handle >>> the intermediate values (IV) by themselves in one bulk block. This means we >>> can increase the size of the request by merging request rather than always 512 >>> bytes and thus increase the hardware engine processing speed. >>> >>> So introduce 'CRYPTO_ALG_BULK' flag to indicate this cipher can support bulk >>> mode. >>> >>> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx> >> >> Nack. As I said before, please do it using explicit IV generators >> like we do for IPsec. > > OK. I would like to try your suggestion. Thanks. 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 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. > >> -- >> Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> >> Home Page: http://gondor.apana.org.au/~herbert/ >> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt > > > > -- > Baolin.wang > Best Regards -- Baolin.wang Best Regards -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
