Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760594AbYJ3Voy (ORCPT ); Thu, 30 Oct 2008 17:44:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760344AbYJ3Vol (ORCPT ); Thu, 30 Oct 2008 17:44:41 -0400 Received: from mail.crca.org.au ([67.207.131.56]:42691 "EHLO crca.org.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760335AbYJ3Vok (ORCPT ); Thu, 30 Oct 2008 17:44:40 -0400 X-Bogosity: Ham, spamicity=0.000000 Subject: Re: [linux-pm] Freezer: Don't count threads waiting for frozen filesystems. From: Nigel Cunningham To: Alan Stern Cc: linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Miklos Szeredi In-Reply-To: References: Content-Type: text/plain Organization: Christian Reformed Churches of Australia Date: Fri, 31 Oct 2008 08:44:20 +1100 Message-Id: <1225403060.6574.10.camel@nigel-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1336 Lines: 34 Hi Alan. On Thu, 2008-10-30 at 09:56 -0400, Alan Stern wrote: > On Fri, 31 Oct 2008, Nigel Cunningham wrote: > > > > Well yeah, your patch handles the straightforward cases. But it > > > doesn't help with the more tricky cases, where one fuse filesystem is > > > using another, and as those may become more widespread, this approach > > > will fail. > > > > At the moment, yes. But it's not impossible for us to modify the patch > > to handle that as well. > > It depends on what you mean. The most direct reading of your statement > is simply wrong: It is _theoretically_ impossible to find the correct > order for freezing filesystems. To do so would be equivalent to > solving the halting problem. I'm not sure that's true. You see, I'm thinking of this as not that different to the problem of unmounting filesystems. There, too, we need to unmount in a particular order, and let transactions on each filesystem stop cleanly before we can unmount them. Even if there are differences, perhaps looking at how we handle unmounting will help with handling freezing. Regards, Nigel -- 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/