Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932271AbXAOMNk (ORCPT ); Mon, 15 Jan 2007 07:13:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932272AbXAOMNj (ORCPT ); Mon, 15 Jan 2007 07:13:39 -0500 Received: from embla.aitel.hist.no ([158.38.50.22]:58517 "HELO embla.aitel.hist.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932271AbXAOMNi (ORCPT ); Mon, 15 Jan 2007 07:13:38 -0500 Message-ID: <45AB6F69.6030004@aitel.hist.no> Date: Mon, 15 Jan 2007 13:11:21 +0100 From: Helge Hafting User-Agent: Icedove 1.5.0.9 (X11/20061220) MIME-Version: 1.0 To: Michael Tokarev CC: Chris Mason , Linus Torvalds , dean gaudet , Viktor , Aubrey , Hua Zhong , Hugh Dickins , linux-kernel@vger.kernel.org, hch@infradead.org, kenneth.w.chen@intel.com, akpm@osdl.org Subject: Re: O_DIRECT question References: <6d6a94c50701101857v2af1e097xde69e592135e54ae@mail.gmail.com> <45A629E9.70502@inbox.ru> <20070112202316.GA28400@think.oraclecorp.com> <45A7F396.4080600@tls.msk.ru> In-Reply-To: <45A7F396.4080600@tls.msk.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 980 Lines: 26 Michael Tokarev wrote: > Chris Mason wrote: > [] > >> I recently spent some time trying to integrate O_DIRECT locking with >> page cache locking. The basic theory is that instead of using >> semaphores for solving O_DIRECT vs buffered races, you put something >> into the radix tree (I call it a placeholder) to keep the page cache >> users out, and lock any existing pages that are present. >> > > But seriously - what about just disallowing non-O_DIRECT opens together > with O_DIRECT ones ? > Please do not create a new local DOS attack. I open some important file, say /etc/resolv.conf with O_DIRECT and just sit on the open handle. Now nobody else can open that file because it is "busy" with O_DIRECT ? Helge Hafting - 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/