Softcrypto infrastructure performance improvements

[Matthew Dillon]

    Alex Hornung and I have tag-teamed the dm_crypt and opencrypto code
    to make it fully asynchronous and distributed across multiple cpus.

    Testing on a Phenom II x 4 software crypto performance has been
    increased from around 50MB/sec to around 124MB/sec through the
    filesystem, using the default crypto, and to around 140MB/sec using
    aes-cbc-plain.

    There are still some issues with the password acceptance code in
    cryptsetup luksOpen that are being tracked down (for some reason
    it often does not accept a valid password and you have to retry).

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>