Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 2 Apr 2001 15:53:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 2 Apr 2001 15:53:34 -0400 Received: from nat-hdqt.valinux.com ([198.186.202.17]:52218 "EHLO tytlal") by vger.kernel.org with ESMTP id ; Mon, 2 Apr 2001 15:53:32 -0400 To: kaos@ocs.com.au Subject: Re: [RFC] sane access to per-fs metadata (was Re: [PATCH] Documentation/ioctl-number.txt) X-Newsgroups: linux.kernel In-Reply-To: <1140.986129422@ocs3.ocs-net> From: chip@valinux.com (Chip Salzenberg) In-Reply-To: Organization: NASA Calendar Research Cc: linux-kernel@vger.kernel.org Message-Id: Date: Mon, 02 Apr 2001 12:49:07 -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org According to kaos@ocs.com.au: >chip@valinux.com (Chip Salzenberg) wrote: >>Why not have a kernel thread and use standard RPC techniques like >>sockets? Then you'd not have to invent anything unimportant like >>Yet Another IPC Technique. > >kerneld (kmod's late unlamented predecessor) used to use Unix sockets >to communicate from the kernel to the daemon. It forced everybody to >link Unix sockets into the kernel but there are some people out there >who want to use it as a module. Also the kernel code for communicating >with kerneld was "unpleasant", see ipc/msg.c in a 2.0 kernel. I see. On the other hand, file-style (e.g. /proc-style) access works in Plan9 at least inpart because each client makes his own connection to the server. Thus, the question of how clients know which response is for them is trivially solved. ('Server' would in this case be the JFS kernel thread.) Sockets are apparently not the right way to go about getting transaction support for kernel threads. AFAIK, Alex Viro's idea of bindable namespaces provides effective transaction support *ONLY* if there are per-process bindings. With per-process bindings, each client that opens a connection does so through a distinct binding; when that client's responses go back through the same binding, only that client can see them. I hope that Alex's namespaces patch, implementing per-process bindings, goes into the official kernel Real Soon Now. -- Chip Salzenberg - a.k.a. - "We have no fuel on board, plus or minus 8 kilograms." -- NEAR tech - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/