From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267382AbUHZAn0 (ORCPT ); Wed, 25 Aug 2004 20:43:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267363AbUHZAnZ (ORCPT ); Wed, 25 Aug 2004 20:43:25 -0400 Received: from rwcrmhc13.comcast.net ([204.127.198.39]:55755 "EHLO rwcrmhc13.comcast.net") by vger.kernel.org with ESMTP id S267380AbUHZAnE (ORCPT ); Wed, 25 Aug 2004 20:43:04 -0400 Subject: Re: silent semantic changes with reiser4 From: Nicholas Miell To: Wichert Akkerman Cc: Jeremy Allison , Andrew Morton , Spam , torvalds@osdl.org, reiser@namesys.com, hch@lst.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, flx@namesys.com, reiserfs-list@namesys.com In-Reply-To: <20040825234629.GF2612@wiggy.net> References: <20040824202521.GA26705@lst.de> <412CEE38.1080707@namesys.com> <20040825152805.45a1ce64.akpm@osdl.org> <112698263.20040826005146@tnonline.net> <1453698131.20040826011935@tnonline.net> <20040825163225.4441cfdd.akpm@osdl.org> <20040825233739.GP10907@legion.cup.hp.com> <20040825234629.GF2612@wiggy.net> Content-Type: text/plain Message-Id: <1093480940.2748.35.camel@entropy> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2.njm.1) Date: Wed, 25 Aug 2004 17:42:21 -0700 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2004-08-25 at 16:46, Wichert Akkerman wrote: > Previously Jeremy Allison wrote: > > Multiple-data-stream files are something we should offer, definately (IMHO). > > I don't care how we do it, but I know it's something we need as application > > developers. > > Aside from samba, is there any other application that has a use for > them? > Anything that currently stores a file's metadata in another file really wants this right now. Things like image thumbnails, document summaries, digital signatures, etc. As to how to do it, I think the Solaris interface is reasonably decent. The overview is at http://docs.sun.com/db/doc/816-0220/6m6nkorp9?a=view (An important detail for those who want to access their multiple-data-streams from non-MDS aware apps is the runat shell command, which basically does a chdir into the specified file's attribute directory and then runs a command. i.e. 'runat ~/blah ls' will list the ~/blah's attributes.) The only real problem I have with their design is the calling them attributes and using "at" everywhere. "Attributes", because it will get confused with the current Linux xattr implementation (which is still useful for things that actually are file attributes, like security labels, ACLs, weird attributess that FAT/NTFS/whatever have, etc.). I don't like "at" because the API changes don't have anything to do with the actual attributes. It's a general set of changes to allow paths relative to a fd instead of the cwd, and doesn't really have anything specifically to do with attributes (with the exception of the O_XATTR flag). Replace "at" with "rel" and O_XATTR with O_FORK or O_MULTI or something, and it's all good.