From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Mahoney Subject: Re: Multiple data streams... Date: Wed, 02 Apr 2003 11:12:29 -0500 Message-ID: <3E8B0BED.2070004@suse.com> References: <6167696812.20030402112847@tnonline.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig84EDE68C224D5C573A0EB4C2" Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <6167696812.20030402112847@tnonline.net> List-Id: To: Anders Widman Cc: reiserfs-list@namesys.com --------------enig84EDE68C224D5C573A0EB4C2 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Anders Widman wrote: > Is this supported, or will it be supported by ReiserFS? > I use this feature quite quite much.. Maybe this is something to > add to ReiserFS? > > There is very brief info at Microsoft's website: > > http://www.microsoft.com/windows2000/techinfo/reskit/en-us/core/fncc_fil_khzt.asp I have an implementation of extended attributes that has been included in the SuSE kernel for some time now. It's not at all suitable for filestreams with a lot of data, as the Linux extended attribute interface requires that the entire attribute be read and written in one chunk. However, for small things, such as mime type, email sender, and perhaps even small thumbprints, this wouldn't be a problem. The sizes of xattrs in my implementation aren't limited in size, as they are implemented as regular files in a hidden tree. [*] The patches are against the SuSE kernel at the moment, but if there's enough interest, I could split them out to depend on the generic ACL/EA patches from Andreas Gruenbacher and Chris Mason's data logging and quota patches. I suppose that since the xattr files are normal files, it would be pretty easy to implement a "datastream" xattr that could be accessed using normal tools. The semantics could be similar to the windows implementation, e.g. /foo/bar/file:datastream1 (Lookup the file verbatim first, then try datastreams) However, since most of the userspace tools are unaware of xattrs, the same restrictions that apply for any other xattr apply: they'll be lost if you copy/backup with tools that don't know about them. -Jeff [*] My design requirements included not forking the filesystem in an incompatible manner, this was the best way I came up with. If a filesystem with xattrs on it is mounted with them disabled or by a kernel that doesn't support them, the xattrs appear in a tree owned by root (mode 700), with all the files owned by the user owning the file that the xattr is associated with. -- jeffm@suse.com jeffm@csh.rit.edu --------------enig84EDE68C224D5C573A0EB4C2 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQE+iwvxLPWxlyuTD7IRArCCAKCHM+qBNE0nYLc7CQw5mV7L2tbyKACdH4WO UzE+2Xu844qrQe87NzPe5gs= =fAMt -----END PGP SIGNATURE----- --------------enig84EDE68C224D5C573A0EB4C2--