From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: silent semantic changes with reiser4 Date: Thu, 26 Aug 2004 09:35:38 -0700 (PDT) Sender: linux-fsdevel-owner@vger.kernel.org Message-ID: References: <20040824202521.GA26705@lst.de> <412CEE38.1080707@namesys.com> <20040825200859.GA16345@lst.de> <20040825203516.GB4688@backtop.namesys.com> <20040825205149.GA17654@lst.de> <412DA2CF.2030204@namesys.com> <20040826124119.GA431@lst.de> <20040826134812.GB5733@mail.shareable.org> <20040826155744.GA4250@lst.de> <20040826160638.GJ5733@mail.shareable.org> <20040826161303.GA4716@lst.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Jamie Lokier , Hans Reiser , Alex Zarochentsev , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Alexander Lyamin aka FLX , ReiserFS List Return-path: Received: from fw.osdl.org ([65.172.181.6]:42161 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S269182AbUHZQfz (ORCPT ); Thu, 26 Aug 2004 12:35:55 -0400 To: Christoph Hellwig In-Reply-To: <20040826161303.GA4716@lst.de> List-Id: linux-fsdevel.vger.kernel.org On Thu, 26 Aug 2004, Christoph Hellwig wrote: > > > Are you saying that with reiser4, you can open a device or fifo with > > O_DIRECTORY? > > That's what I thought, but as far as I can follow the code this is not > actually true. It should be possible to do, though. There's nothing really different in making the "default" (unnamed) fork be a special device or a fifo. And it would be perfectly ok for O_DIRECTORY to open such a file, as long as it opens the directory branch, not the special device. I advocated (long ago) something like this for /dev handling, just because I think it would make sense to have /dev/hda <- special file /dev/hda/part1 <- partition 1 (aka /dev/hda1) which just seems like a very obvious and intuitive interface to me. Of course, we have so much legacy in /dev that there's no real point to doing this, but it's still an appealing approach, I think. But I do take Al's concerns seriously. I like the notion of supporting "containers", but there are undoubtedly serious issues in the notion. I don't strictly know exactly _how_ to implement it sanely (I can talk about using the vfsmnt structure all I like, but the fact is, it's a different thing from a normal mount, and there may be serious problems indeed there). Still, I really do like the idea of merging the notion of file and directory into one notion of "container". I absolutely _detest_ files with internal structure that tools have to know about (ie I hate seeing all those embedded formats that I can't use "grep" on - MIME being one case). I'd much rather see a "group of files" and a "file with a grouping of information". (Now, flattening that "group of files" is obviously needed for serial protocols, so I think MIME/tar/xxxx are fine for _transporting_ data, but I'm saying that outside of transport I really prefer a "collection of files" approach). Linus