Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752972AbWKHO0E (ORCPT ); Wed, 8 Nov 2006 09:26:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754584AbWKHO0D (ORCPT ); Wed, 8 Nov 2006 09:26:03 -0500 Received: from mx1.redhat.com ([66.187.233.31]:29398 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1752972AbWKHO0B (ORCPT ); Wed, 8 Nov 2006 09:26:01 -0500 Date: Wed, 8 Nov 2006 14:25:11 +0000 From: Alasdair G Kergon To: David Chinner Cc: "Rafael J. Wysocki" , Eric Sandeen , Andrew Morton , Alasdair G Kergon , linux-kernel@vger.kernel.org, dm-devel@redhat.com, Ingo Molnar , Srinivasa DS Subject: Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex Message-ID: <20061108142511.GG30653@agk.surrey.redhat.com> Mail-Followup-To: David Chinner , "Rafael J. Wysocki" , Eric Sandeen , Andrew Morton , Alasdair G Kergon , linux-kernel@vger.kernel.org, dm-devel@redhat.com, Ingo Molnar , Srinivasa DS References: <20061107183459.GG6993@agk.surrey.redhat.com> <200611080005.50070.rjw@sisk.pl> <45511430.8030703@redhat.com> <200611080042.03563.rjw@sisk.pl> <20061108000109.GE30653@agk.surrey.redhat.com> <20061108082722.GH8394166@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061108082722.GH8394166@melbourne.sgi.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 951 Lines: 19 On Wed, Nov 08, 2006 at 07:27:22PM +1100, David Chinner wrote: > But it's trivial to detect this condition - if (sb->s_frozen != SB_UNFROZEN) > then the filesystem is already frozen and you shouldn't try to freeze > it again. It's simple to do, and the whole problem then just goes away.... So is that another vote in support of explicitly supporting multiple concurrent freeze requests, letting them all succeed, and only thawing after the last one has requested its thaw? (It's not enough just to check SB_UNFROZEN - also need to track whether any other outstanding requests to avoid risk of it getting unfrozen while something independent believes it still to be frozen.) Alasdair -- agk@redhat.com - 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/