From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f169.google.com ([209.85.213.169]:41628 "EHLO mail-ig0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750816AbaKZN64 (ORCPT ); Wed, 26 Nov 2014 08:58:56 -0500 Received: by mail-ig0-f169.google.com with SMTP id hl2so8545132igb.4 for ; Wed, 26 Nov 2014 05:58:56 -0800 (PST) Message-ID: <5475DC9A.3060003@gmail.com> Date: Wed, 26 Nov 2014 08:58:50 -0500 From: Austin S Hemmelgarn MIME-Version: 1.0 To: Brendan Hide , dsterba@suse.cz, Chris Mason , Liu Bo , linux-btrfs Subject: Re: [RFC PATCH] Btrfs: add sha256 checksum option References: <1416806586-18050-1-git-send-email-bo.li.liu@oracle.com> <1416859665.3019.6@mail.thefacebook.com> <20141125164717.GK26471@twin.jikos.cz> <5475D7F3.4040408@swiftspirit.co.za> In-Reply-To: <5475D7F3.4040408@swiftspirit.co.za> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms080701030107020107020600" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms080701030107020107020600 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable On 2014-11-26 08:38, Brendan Hide wrote: > On 2014/11/25 18:47, David Sterba wrote: >> We could provide an interface for external applications that would mak= e >> use of the strong checksums. Eg. external dedup, integrity db. The >> benefit here is that the checksum is always up to date, so there's no >> need to compute the checksums again. At the obvious cost. > > I can imagine some use-cases where you might even want more than one > algorithm to be used and stored. Not sure if that makes me a madman, > though. ;) > Not crazy at all, I would love to have the ability to store multiple=20 different weak but fast hash values. For example, on my laptop, it is=20 actually faster to compute crc32c, adler32, and md5 hashes together than = it is to compute pretty much any 256-bit hash I've tried. This then brings up the issue of what to do when we try to mount such a=20 fs on a system that doesn't support some or all of the hashes used. --------------ms080701030107020107020600 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIFuDCC BbQwggOcoAMCAQICAw9gVDANBgkqhkiG9w0BAQ0FADB5MRAwDgYDVQQKEwdSb290IENBMR4w HAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmlu ZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZzAeFw0xNDA4 MDgxMTMwNDRaFw0xNTAyMDQxMTMwNDRaMGMxGDAWBgNVBAMTD0NBY2VydCBXb1QgVXNlcjEj MCEGCSqGSIb3DQEJARYUYWhmZXJyb2luN0BnbWFpbC5jb20xIjAgBgkqhkiG9w0BCQEWE2Fo ZW1tZWxnQG9oaW9ndC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDdmm8R BM5D6fGiB6rpogPZbLYu6CkU6834rcJepfmxKnLarYUYM593/VGygfaaHAyuc8qLaRA3u1M0 Qp29flqmhv1VDTBZ+zFu6JgHjTDniBii1KOZRo0qV3jC5NvaS8KUM67+eQBjm29LhBWVi3+e a8jLxmogFXV0NGej+GHIr5zA9qKz2WJOEoGh0EfqZ2MQTmozcGI43/oqIYhRj8fRMkWXLUAF WsLzPQMpK19hD8fqwlxQWhBV8gsGRG54K5pyaQsjne7m89SF5M8JkNJPH39tHEvfv2Vhf7EM Y4WGyhLAULSlym1AI1uUHR1FfJaj3AChaEJZli/AdajYsqc7AgMBAAGjggFZMIIBVTAMBgNV HRMBAf8EAjAAMFYGCWCGSAGG+EIBDQRJFkdUbyBnZXQgeW91ciBvd24gY2VydGlmaWNhdGUg Zm9yIEZSRUUgaGVhZCBvdmVyIHRvIGh0dHA6Ly93d3cuQ0FjZXJ0Lm9yZzAOBgNVHQ8BAf8E BAMCA6gwQAYDVR0lBDkwNwYIKwYBBQUHAwQGCCsGAQUFBwMCBgorBgEEAYI3CgMEBgorBgEE AYI3CgMDBglghkgBhvhCBAEwMgYIKwYBBQUHAQEEJjAkMCIGCCsGAQUFBzABhhZodHRwOi8v b2NzcC5jYWNlcnQub3JnMDEGA1UdHwQqMCgwJqAkoCKGIGh0dHA6Ly9jcmwuY2FjZXJ0Lm9y Zy9yZXZva2UuY3JsMDQGA1UdEQQtMCuBFGFoZmVycm9pbjdAZ21haWwuY29tgRNhaGVtbWVs Z0BvaGlvZ3QuY29tMA0GCSqGSIb3DQEBDQUAA4ICAQCr4klxcZU/PDRBpUtlb+d6JXl2dfto OUP/6g19dpx6Ekt2pV1eujpIj5whh5KlCSPUgtHZI7BcksLSczQbxNDvRu6LNKqGJGvcp99k cWL1Z6BsgtvxWKkOmy1vB+2aPfDiQQiMCCLAqXwHiNDZhSkwmGsJ7KHMWgF/dRVDnsl6aOQZ jAcBMpUZxzA/bv4nY2PylVdqJWp9N7x86TF9sda1zRZiyUwy83eFTDNzefYPtc4MLppcaD4g Wt8U6T2ffQfCWVzDirhg4WmDH3MybDItjkSB2/+pgGOS4lgtEBMHzAGQqQ+5PojTHRyqu9Jc O59oIGrTaOtKV9nDeDtzNaQZgygJItJi9GoAl68AmIHxpS1rZUNV6X8ydFrEweFdRTVWhUEL 70Cnx84YBojXv01LYBSZaq18K8cERPLaIrUD2go+2ffjdE9ejvYDhNBllY+ufvRizIjQA1uC OdktVAN6auQob94kOOsWpoMSrzHHvOvVW/kbokmKzaLtcs9+nJoL+vPi2AyzbaoQASVZYOGW pE3daA0F5FJfcPZKCwd5wdnmT3dU1IRUxa5vMmgjP20lkfP8tCPtvZv2mmI2Nw5SaXNY4gVu WQrvkV2in+TnGqgEIwUrLVbx9G6PSYZZs07czhO+Q1iVuKdAwjL/AYK0Us9v50acIzbl5CWw ZGj3wjGCA6EwggOdAgEBMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6 Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEh MB8GCSqGSIb3DQEJARYSc3VwcG9ydEBjYWNlcnQub3JnAgMPYFQwCQYFKw4DAhoFAKCCAfUw GAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTQxMTI2MTM1ODUw WjAjBgkqhkiG9w0BCQQxFgQUG0RDQLTmNDR3Aa+uVEUY0GvZmxEwbAYJKoZIhvcNAQkPMV8w XTALBglghkgBZQMEASowCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIA gDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKDCBkQYJKwYBBAGCNxAE MYGDMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0 Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJ ARYSc3VwcG9ydEBjYWNlcnQub3JnAgMPYFQwgZMGCyqGSIb3DQEJEAILMYGDoIGAMHkxEDAO BgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UE AxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJARYSc3VwcG9ydEBj YWNlcnQub3JnAgMPYFQwDQYJKoZIhvcNAQEBBQAEggEAFAJcnivGMNW9eoWtFvqruYQ2NKiV x4JzuTpkQriL94FElRk1hZVgeWOr6ft8Y2S8p6GinPgxe/FZlcu91EjY8aFeZW5aG4ZkNkJG Ha9FwGZO/XjUjD9vAewBwQzeJcCAvs9GDP1xU/v5G/wNLPovibnhiKNdDQECZfCM8RSzNc9G wJwIl60dvQn4M4/owJnUcC3/tfLS8paRhNzvIk42cTYCm90ERcTA/zKUd7YxChwBjytpdcm5 CBydfKJ+SK5l2G2+oYy0dxmPgDsAuixaTwZC7AOr0h6a7ZWUfXYo1aflbCaHgTvm/MFJg0Ts Bw2vv2jGl/3uU7GMjOwZK6Z4rwAAAAAAAA== --------------ms080701030107020107020600--