From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f176.google.com ([209.85.223.176]:32945 "EHLO mail-io0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753917AbbJPLrY (ORCPT ); Fri, 16 Oct 2015 07:47:24 -0400 Subject: Re: [PATCH v5 8/9] vfs: Add vfs_copy_file_range() support for pagecache copies To: Christoph Hellwig References: <1443634014-3026-1-git-send-email-Anna.Schumaker@Netapp.com> <1443634014-3026-9-git-send-email-Anna.Schumaker@Netapp.com> <20151011142203.GA31867@infradead.org> <20151012231749.GC11398@birch.djwong.org> <561E980C.9010509@Netapp.com> <20151014182701.GC31225@infradead.org> <561EA83E.8080000@gmail.com> <20151015063621.GA3025@infradead.org> <561F9B13.7020804@gmail.com> <20151016053808.GA29510@infradead.org> Cc: Andy Lutomirski , Anna Schumaker , "Darrick J. Wong" , linux-nfs@vger.kernel.org, Linux btrfs Developers List , Linux FS Devel , Linux API , Zach Brown , Al Viro , Chris Mason , Michael Kerrisk-manpages , andros@netapp.com From: Austin S Hemmelgarn Message-ID: <5620E3A1.90408@gmail.com> Date: Fri, 16 Oct 2015 07:46:41 -0400 MIME-Version: 1.0 In-Reply-To: <20151016053808.GA29510@infradead.org> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms050908060709090708020809" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms050908060709090708020809 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-10-16 01:38, Christoph Hellwig wrote: > On Thu, Oct 15, 2015 at 08:24:51AM -0400, Austin S Hemmelgarn wrote: >> My only point with saying we shouldn't reflink by default is that ther= e are >> many (unintelligent) people who will assume that since the syscall has= copy >> in it's name, that's what it will do; and, while I don't think we shou= ld >> cater to such individuals, it does make sense to have a syscall that s= ays in >> it's name that it copies data actually do so by default. > > As far as the user is concerned a reflink is a copy. A very efficient > copy. I should have been specific, what I meant was that some people will=20 assume that it actually creates a physical, on-disk byte-for-byte copy=20 of the data. There are many people out there (and sadly I have to deal=20 with some at work) who are absolutely terrified of the concept of data=20 deduplication, and will likely refuse to use this syscall for _anything_ = if it reflinks by default on filesystems that support it. --------------ms050908060709090708020809 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 hvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTUxMDE2MTE0NjQxWjBPBgkq hkiG9w0BCQQxQgRAjiG9v3R6ktr9y88i7uz33BX6UsRnicjXhFKA/lpqGL2eVxBmqWPKrDxE 83qYRum51Xt+fRqQO0p3mEjqD14mUzBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIGRBgkrBgEEAYI3EAQxgYMwgYAweTEQMA4GA1UE ChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlD QSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy dC5vcmcCAxEt+DCBkwYLKoZIhvcNAQkQAgsxgYOggYAweTEQMA4GA1UEChMHUm9vdCBDQTEe MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25p bmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DAN BgkqhkiG9w0BAQEFAASCAgBnfw/4FE1Ug3nx5TeunM85OWdUVC0uyJYVehMhhpbIOfWGdKLx /6WbkMglrDoqRYuNOOLYxBpf8kfh1mA+kTf4PbPAlZE7lqHjXI+TInDDsGnGzm2geTq6I6vO 01tE9yt4AOxXraTUS+1SbVvAHMoLn0l2w5yD2DW6W4CK7cO96ZqZCaFtXrS+VZM7zO7GyI3s kpSI+m/+VtsD10gRO7aGMuSdol1WD5WTbZGnZbpd68NUuA8g2zI9+cKRC+IE3glh6vrP9Wlu Jc+TPjYomo7APQRLKQTz/epiQqBfyHS2KRhwPcgno/8OhnOWfvyRa7HJXWojxqL6JYoE0uPL MIPkvHyZjmImOY9baRyn3c6Iy/0f6ZaDKQEhFzjvk3i01KzlQsG7f0ldsRPs3Jtb3EV1RL2p s/jY+PtofoZuuYpZR/jwQeHXvJPk1e1Eddkoyg7jm2fpaL6G1iK5KA6izKTj5xQUKbm96l/t gWhcaiSyPI94A3YqHZTytgK7p3dtXF6wBEEfjPI3/rp9QPAx3ECFxi0JM8clHYScKVbZW5iP 3paaPeHF+meb8+sX4F/ijfv1hXsMNXcOg5arXaks0EmLdCaGvzGD0J1x6TgwJZdSX8/bpGqX 7DEk5nLYqANQvwV6BmqxVJ294Sn87AlKjSoW+6Y0cpaQQ+E9WkaWqzBL6wAAAAAAAA== --------------ms050908060709090708020809--