Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933639AbWKQPOK (ORCPT ); Fri, 17 Nov 2006 10:14:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933655AbWKQPOK (ORCPT ); Fri, 17 Nov 2006 10:14:10 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:59342 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S933639AbWKQPOH (ORCPT ); Fri, 17 Nov 2006 10:14:07 -0500 Date: Fri, 17 Nov 2006 16:13:48 +0100 From: Pavel Machek To: David Chinner Cc: "Rafael J. Wysocki" , Alasdair G Kergon , Eric Sandeen , Andrew Morton , linux-kernel@vger.kernel.org, dm-devel@redhat.com, Srinivasa DS , Nigel Cunningham Subject: Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex Message-ID: <20061117151348.GA8859@elf.ucw.cz> References: <20061107183459.GG6993@agk.surrey.redhat.com> <20061110103942.GG3196@elf.ucw.cz> <20061112223012.GH11034@melbourne.sgi.com> <200611122343.06625.rjw@sisk.pl> <20061116232349.GI11034@melbourne.sgi.com> <20061116234053.GC6757@elf.ucw.cz> <20061117014051.GM11034@melbourne.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061117014051.GM11034@melbourne.sgi.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1861 Lines: 39 On Fri 2006-11-17 12:40:51, David Chinner wrote: > On Fri, Nov 17, 2006 at 12:40:53AM +0100, Pavel Machek wrote: > > On Fri 2006-11-17 10:23:49, David Chinner wrote: > > > On Sun, Nov 12, 2006 at 11:43:05PM +0100, Rafael J. Wysocki wrote: > > > > On Sunday, 12 November 2006 23:30, David Chinner wrote: > > > > > And how does freezing them at that point in time guarantee consistent > > > > > filesystem state? > > > > > > > > If the work queues are frozen, there won't be any fs-related activity _after_ > > > > we create the suspend image. > > > > > > fs-related activity before or after the suspend image is captured is > > > not a problem - it's fs-related activity _during_ the suspend that > > > is an issue here. If we have async I/O completing during the suspend > > > image capture, we've got problems.... > > > > fs-related activity _after_ image is captured definitely is a problem > > -- it breaks swsusp invariants. > > > > During image capture, any fs-related activity is not possible, as we > > are running interrupts disabled, DMA disabled. > > Ok, so the I/o that finishes during the image capture won't be reported > until after the capture completes. that means we lose the capability There's no I/O in flight during image capture. Interrupts are disabled, DMAs are stopped, and drivers were told to shut down (that includes finishing any outstanding work, and drivers do that currently; but perhaps docs should be more explicit about it). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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/