Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761099AbZAPQJA (ORCPT ); Fri, 16 Jan 2009 11:09:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753062AbZAPQIt (ORCPT ); Fri, 16 Jan 2009 11:08:49 -0500 Received: from mx2.redhat.com ([66.187.237.31]:58868 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750942AbZAPQIs (ORCPT ); Fri, 16 Jan 2009 11:08:48 -0500 Message-ID: <4970B0F2.6040507@redhat.com> Date: Fri, 16 Jan 2009 10:08:18 -0600 From: Eric Sandeen User-Agent: Thunderbird 2.0.0.19 (Macintosh/20081209) MIME-Version: 1.0 To: Theodore Tso , Valdis.Kletnieks@vt.edu, Pavel Machek , Eric Sandeen , linux-fsdevel , linux-kernel Mailing List , Andrew Morton , Takashi Sato Subject: Re: [PATCH] Allow SysRq emergency sync to thaw frozen filesystems References: <496EB639.6090800@redhat.com> <20090116084828.GB4795@atrey.karlin.mff.cuni.cz> <16406.1232119029@turing-police.cc.vt.edu> <20090116154026.GG10683@mit.edu> In-Reply-To: <20090116154026.GG10683@mit.edu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1553 Lines: 35 Theodore Tso wrote: > On Fri, Jan 16, 2009 at 10:17:09AM -0500, 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... > > My biggest complaint is that the two operations are largely > orthogonal. Emergency sync and unfreeze are two very different > operations, and while emergency sync is largely harmless, it just > seems really unclean to combine the two. For one thing, it'll be > extremely non-obvious that emergency sync implies unfreeze, and > changing the sysrq help to say emergency-Sync-and-unfreeze just > screams "kludge".... > > - Ted Yeah, they really are orthogonal, it's true. Ok, if people are willing to give up 'z' I'll move it there. -Eric -- 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/