From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f179.google.com ([209.85.213.179]:34553 "EHLO mail-ig0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753517AbbK3MaQ (ORCPT ); Mon, 30 Nov 2015 07:30:16 -0500 Received: by igvg19 with SMTP id g19so68846405igv.1 for ; Mon, 30 Nov 2015 04:30:15 -0800 (PST) Subject: Re: [PATCH v2 1/5] btrfs-progs: introduce framework to check kernel supported features To: dsterba@suse.cz, Mike Fleetwood , Anand Jain , linux-btrfs References: <1448283378-10579-1-git-send-email-anand.jain@oracle.com> <1448283378-10579-2-git-send-email-anand.jain@oracle.com> <5654C6BF.8010502@gmail.com> <20151126173850.GV31035@twin.jikos.cz> From: Austin S Hemmelgarn Message-ID: <565C4152.8040103@gmail.com> Date: Mon, 30 Nov 2015 07:30:10 -0500 MIME-Version: 1.0 In-Reply-To: <20151126173850.GV31035@twin.jikos.cz> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms000002030008010409070108" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms000002030008010409070108 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-11-26 12:38, David Sterba wrote: > On Tue, Nov 24, 2015 at 03:21:19PM -0500, Austin S Hemmelgarn wrote: >>> I think you mean 2.6.37 here. >>> 67377734fd24c3 "Btrfs: add support for mixed data+metadata block grou= ps" >> This brings up a rather important question: >> Should compat-X.Y mean features that were considered usable in that >> version, or everything that version offered? I understand wanting >> consistency with the kernel versions, but we shouldn't be creating >> filesystems that we know will break on the specified kernel even if it= >> is mountable on it. > > IMO compat refers to the compatibility feature bits so it's whether the= > filesystem is mountable on a given version. Usability can be subjective= =2E > I assume the kernel versions in wide use match some of the long term > branches. If it's k.org, we can submit the fixes and distros update > their long term branches. My point was that if we know that there's a significant chance of either = data corruption or a kernel crash when using a given feature with a=20 given kernel, we should not turn on that feature for that kernel. For=20 every other project I've ever seen, compatible means that you can be=20 fairly certain that it won't crash, and won't destroy data. There is no = excuse for knowingly making filesystems that will break the system. Also, expecting the distros to keep up with development given the pace=20 at which BTRFS is moving is not all that realistic. Secondarily, at=20 least Ubuntu has a habit of picking kernel versions that aren't marked=20 LTS by kernel.org. > > A table of "is the feature usable" would be interesting but I think it'= s > for wiki. I'd say it would be a lot more helpful in the manpage than in the wiki=20 (if you're reprovisioning a system, you don't necessarily have access to = the wiki). --------------ms000002030008010409070108 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgMFADCABgkqhkiG9w0BBwEAAKCC Brgwgga0MIIEnKADAgECAgMRLfgwDQYJKoZIhvcNAQENBQAweTEQMA4GA1UEChMHUm9vdCBD QTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNp Z25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcwHhcN MTUwOTIxMTEzNTEzWhcNMTYwMzE5MTEzNTEzWjBjMRgwFgYDVQQDEw9DQWNlcnQgV29UIFVz ZXIxIzAhBgkqhkiG9w0BCQEWFGFoZmVycm9pbjdAZ21haWwuY29tMSIwIAYJKoZIhvcNAQkB FhNhaGVtbWVsZ0BvaGlvZ3QuY29tMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEA nQ/81tq0QBQi5w316VsVNfjg6kVVIMx760TuwA1MUaNQgQ3NyUl+UyFtjhpkNwwChjgAqfGd LIMTHAdObcwGfzO5uI2o1a8MHVQna8FRsU3QGouysIOGQlX8jFYXMKPEdnlt0GoQcd+BtESr pivbGWUEkPs1CwM6WOrs+09bAJP3qzKIr0VxervFrzrC5Dg9Rf18r9WXHElBuWHg4GYHNJ2V Ab8iKc10h44FnqxZK8RDN8ts/xX93i9bIBmHnFfyNRfiOUtNVeynJbf6kVtdHP+CRBkXCNRZ qyQT7gbTGD24P92PS2UTmDfplSBcWcTn65o3xWfesbf02jF6PL3BCrVnDRI4RgYxG3zFBJuG qvMoEODLhHKSXPAyQhwZINigZNdw5G1NqjXqUw+lIqdQvoPijK9J3eijiakh9u2bjWOMaleI SMRR6XsdM2O5qun1dqOrCgRkM0XSNtBQ2JjY7CycIx+qifJWsRaYWZz0aQU4ZrtAI7gVhO9h pyNaAGjvm7PdjEBiXq57e4QcgpwzvNlv8pG1c/hnt0msfDWNJtl3b6elhQ2Pz4w/QnWifZ8E BrFEmjeeJa2dqjE3giPVWrsH+lOvQQONsYJOuVb8b0zao4vrWeGmW2q2e3pdv0Axzm/60cJQ haZUv8+JdX9ZzqxOm5w5eUQSclt84u+D+hsCAwEAAaOCAVkwggFVMAwGA1UdEwEB/wQCMAAw VgYJYIZIAYb4QgENBEkWR1RvIGdldCB5b3VyIG93biBjZXJ0aWZpY2F0ZSBmb3IgRlJFRSBo ZWFkIG92ZXIgdG8gaHR0cDovL3d3dy5DQWNlcnQub3JnMA4GA1UdDwEB/wQEAwIDqDBABgNV HSUEOTA3BggrBgEFBQcDBAYIKwYBBQUHAwIGCisGAQQBgjcKAwQGCisGAQQBgjcKAwMGCWCG SAGG+EIEATAyBggrBgEFBQcBAQQmMCQwIgYIKwYBBQUHMAGGFmh0dHA6Ly9vY3NwLmNhY2Vy dC5vcmcwMQYDVR0fBCowKDAmoCSgIoYgaHR0cDovL2NybC5jYWNlcnQub3JnL3Jldm9rZS5j cmwwNAYDVR0RBC0wK4EUYWhmZXJyb2luN0BnbWFpbC5jb22BE2FoZW1tZWxnQG9oaW9ndC5j b20wDQYJKoZIhvcNAQENBQADggIBADMnxtSLiIunh/TQcjnRdf63yf2D8jMtYUm4yDoCF++J jCXbPQBGrpCEHztlNSGIkF3PH7ohKZvlqF4XePWxpY9dkr/pNyCF1PRkwxUURqvuHXbu8Lwn 8D3U2HeOEU3KmrfEo65DcbanJCMTTW7+mU9lZICPP7ZA9/zB+L0Gm1UNFZ6AU50N/86vjQfY WgkCd6dZD4rQ5y8L+d/lRbJW7ZGEQw1bSFVTRpkxxDTOwXH4/GpQfnfqTAtQuJ1CsKT12e+H NSD/RUWGTr289dA3P4nunBlz7qfvKamxPymHeBEUcuICKkL9/OZrnuYnGROFwcdvfjGE5iLB kjp/ttrY4aaVW5EsLASNgiRmA6mbgEAMlw3RwVx0sVelbiIAJg9Twzk4Ct6U9uBKiJ8S0sS2 8RCSyTmCRhJs0vvva5W9QUFGmp5kyFQEoSfBRJlbZfGX2ehI2Hi3U2/PMUm2ONuQG1E+a0AP u7I0NJc/Xil7rqR0gdbfkbWp0a+8dAvaM6J00aIcNo+HkcQkUgtfrw+C2Oyl3q8IjivGXZqT 5UdGUb2KujLjqjG91Dun3/RJ/qgQlotH7WkVBs7YJVTCxfkdN36rToPcnMYOI30FWa0Q06gn F6gUv9/mo6riv3A5bem/BdbgaJoPnWQD9D8wSyci9G4LKC+HQAMdLmGoeZfpJzKHMYIE0TCC BM0CAQEwgYAweTEQMA4GA1UEChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNl cnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcN AQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DANBglghkgBZQMEAgMFAKCCAiEwGAYJKoZI hvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTUxMTMwMTIzMDEwWjBPBgkq hkiG9w0BCQQxQgRArdfLQ8U5gC/kFMUZ6k74bQbv9Kj4qyo4di6TbzIYeznXg97T15HlPPlf 1JLd57Tgdghr84u+QNyaWszwrWh/FjBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIGRBgkrBgEEAYI3EAQxgYMwgYAweTEQMA4GA1UE ChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlD QSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy dC5vcmcCAxEt+DCBkwYLKoZIhvcNAQkQAgsxgYOggYAweTEQMA4GA1UEChMHUm9vdCBDQTEe MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25p bmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DAN BgkqhkiG9w0BAQEFAASCAgCMmvyPGW0nqQcE/O66sbuUVC1lzQlNJ7ouXa68l0ZcpB5tMtEp Jv50Li/24yOP6Gz4AlobflSHQEvo7qNUBy1MCBjFPZz9HSG6GjtTTh3fkCipmVM6OYRPOH+D 7fZ91/cHeYLDQocUCjYrWQWa1UUqKpgsdqwiZa8nvaAP/H4GIOBUFYevV1WoUFQzMXw8/1ve V3pPA1L6c8n477qchqPidCqrXDHbDI4xa9HYZwgGn9eSW6sTtLKrQVJYSYkte+hMG8w5haLZ 5iYDbbK3lsLAxorPCjsTk5YRxKJZbFKgc5EiZYUz9vapQXdDn1j9H+CnHImAgpou+NCcKA/T Ko9ctzcyb8aYnsfoqur2ojzuRYepaWX8o9XlZNv8uGzjgtmujyZ80mPELrmHvG9ItjmxcE/r qFFcifXRf5KxQL/vK+JrRj5PkGjFahxwV6Dj0loBgLe6vdrT5oj9LRcdlt2d57A2fTnMgL37 n+fcH2zGe0llbFFurnGTxJHfkLYxEsK6OcXwirCpzuzghPrq3EXClS0EEoMpsqfeK7fctegI ZlPy6X+JHtRkUFOnJZdQsJnj7+/atiwAYEpXHsx1qn25NgNrYOTxtYdLX/QOpEXJMKXzalqr 8wFZ4v1NidCMXJz5wagwg7DRVp08wWXqfqDtPE+2pvY/aps90J42q+tuywAAAAAAAA== --------------ms000002030008010409070108--