From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: [PATCH] Allow SysRq emergency sync to thaw frozen filesystems Date: Fri, 16 Jan 2009 09:28:11 -0600 Message-ID: <4970A78B.8050605@redhat.com> References: <496EB639.6090800@redhat.com> <20090116084828.GB4795@atrey.karlin.mff.cuni.cz> <16406.1232119029@turing-police.cc.vt.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Pavel Machek , linux-fsdevel , linux-kernel Mailing List , Andrew Morton , Takashi Sato To: Valdis.Kletnieks@vt.edu Return-path: Received: from mx2.redhat.com ([66.187.237.31]:53463 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759002AbZAPP2U (ORCPT ); Fri, 16 Jan 2009 10:28:20 -0500 In-Reply-To: <16406.1232119029@turing-police.cc.vt.edu> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Valdis.Kletnieks@vt.edu wrote: > On Fri, 16 Jan 2009 09:48:28 +0100, Pavel Machek said: > >> Emergency Sync should not do this. Invent another key. >> >> ...because otherwise, if you hit emergency sync but the system is >> still alive and relies on filesystem freezing, bad stuff will happen. > > Under what conditions would a system be alive and relying on freezing, > *and* an emergency thaw would be worse than whatever reason you're doing > an emergency sync? > > Hmm.. guess you *could* get into trouble if you tried to do a Sysrq-[not-s] > and hit the wrong key - but you have the same danger if you have *any* > sysrq- invoking an emergency_thaw and hit it by accident... I could certainly use up another key ('z' is available for unfreeZe) but I have the same question; under what conditions do you expect to need an emergency sync and also need to maintain frozen filesystems as frozen? >>From a maximum flexibility and control perspective, it'd be better to have them separated I suppose. Is it worth using up another available key? -Eric