From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f176.google.com ([209.85.223.176]:35376 "EHLO mail-ie0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754888AbaLVUoT (ORCPT ); Mon, 22 Dec 2014 15:44:19 -0500 Received: by mail-ie0-f176.google.com with SMTP id tr6so5049537ieb.35 for ; Mon, 22 Dec 2014 12:44:19 -0800 (PST) Message-ID: <5498829E.3060608@gmail.com> Date: Mon, 22 Dec 2014 15:44:14 -0500 From: Austin S Hemmelgarn MIME-Version: 1.0 To: Richard Sharpe , Chris Murphy CC: Btrfs BTRFS Subject: Re: Can BTRFS handle XATTRs larger than 4K? References: <54982A79.1090102@gmail.com> <54985E4C.40003@gmail.com> In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms000102010903060203010504" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms000102010903060203010504 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 2014-12-22 15:06, Richard Sharpe wrote: > On Mon, Dec 22, 2014 at 10:43 AM, Chris Murphy wrote: >> On Mon, Dec 22, 2014 at 11:09 AM, Austin S Hemmelgarn >> wrote: >> >>> Personally, I'd love to see unlimited length xattr's like NTFS and HF= S+ do, >>> as that would greatly improve interoperability (both Windows and OS X= use >>> xattrs, although they call them 'alternative data streams' and 'forks= ' >>> respectively), and provide a higher likelihood that xattrs would star= t >>> getting used more. >> >> This is two years old, but it looks like NFS will not support xattr. >> http://comments.gmane.org/gmane.linux.nfs/53259 >> >> It looks like SMB does support xattr (and sometimes requires it) but I= >> have no idea to what degree, including the host/client preservation on= >> different filesystems. [1] It would still be helpful for cp and rsync >> to be able to preserve xattr, however Apple has moved to a new on-disk= >> format that makes the future of reading OS X volumes on Linux an open >> question. [2] > > Those are the old OS 2 XATTRs, better known as EAs, and NTFS says that > you can support EAs or you can have Reparse Points, but not both > (basically, they re-used the EA Length field as the reparse tag). > Also, Windows (of any flavor) does not make it easy to access EAs. > But OS/2 style XATTRS are not the same as NTFS Alternative Data Streams, = which technically (because of Windows backward compatibility interfaces) = don't need a huge amount of support from SMB. They were originally=20 added to support SFM in NT3.1, so that windows could store resource=20 forks. The two primary uses on windows today are the file history=20 interface in Win8/8.1 and the 'zone_identifier' saved with downloads by=20 most modern browsers. They're actually pretty easy to get to, you just=20 append the ADS name to the end of the filename with a : separating them, = and you can access it like a regular file (which is part of why : isn't=20 a legal character in a windows filename). Most people don't know about=20 them because they don't get listed in windows explorer, even with hidden = files and protected OS file visible. The actual on-disk format for them = is actually kind of interesting, the file data itself (what in the Apple = world is called the Data Fork) is actually stored as an unnamed ADS=20 associated with the filename. --------------ms000102010903060203010504 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 GAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTQxMjIyMjA0NDE0 WjAjBgkqhkiG9w0BCQQxFgQUctZVJ6wyR5FBvel0NfrCUgkLOtwwbAYJKoZIhvcNAQkPMV8w XTALBglghkgBZQMEASowCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIA gDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKDCBkQYJKwYBBAGCNxAE MYGDMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0 Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJ ARYSc3VwcG9ydEBjYWNlcnQub3JnAgMPYFQwgZMGCyqGSIb3DQEJEAILMYGDoIGAMHkxEDAO BgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UE AxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJARYSc3VwcG9ydEBj YWNlcnQub3JnAgMPYFQwDQYJKoZIhvcNAQEBBQAEggEAKYeEOVLx6aUOYBWzqV9NzRM2pJ3x WaNTOTgBnnFeZHiQz/UrXw0b5An17yjJZMP8XZsKtK3q+23voX9l+V/pmRNRYBckyZRWO1o9 dVORejvrMZUGhwHR2Xp2QpBs+Fde85rCQZc+G0xLririO0QwAYhMPsJqxQHq99aJrWiZniyl T/+Px4Jx3CAxYKuBqtUMqoFOzeowBxufA3hwJEf9Hi/V/Idi5nX41KcDoO9jQ/TEBiHoH3yK x3SN57T9FpoL1lERF5OSwjf5t/dAXdhWboPqe+Pqww7ZHD8oY4zvhvaFEz+vqzr6s3Ddps0C HAiF03ogdDQjyl66P2H90VsGtQAAAAAAAA== --------------ms000102010903060203010504--