Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753832AbWKGXeh (ORCPT ); Tue, 7 Nov 2006 18:34:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753867AbWKGXeh (ORCPT ); Tue, 7 Nov 2006 18:34:37 -0500 Received: from mx1.redhat.com ([66.187.233.31]:18125 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1753832AbWKGXeh (ORCPT ); Tue, 7 Nov 2006 18:34:37 -0500 Date: Tue, 7 Nov 2006 23:34:20 +0000 From: Alasdair G Kergon To: device-mapper development Cc: Andrew Morton , linux-kernel@vger.kernel.org, Ingo Molnar , Eric Sandeen , Srinivasa DS Subject: Re: [dm-devel] [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex Message-ID: <20061107233420.GC30653@agk.surrey.redhat.com> Mail-Followup-To: device-mapper development , Andrew Morton , linux-kernel@vger.kernel.org, Ingo Molnar , Eric Sandeen , Srinivasa DS References: <20061107183459.GG6993@agk.surrey.redhat.com> <170fa0d20611071218t3c145ef9i5413e432597d78a5@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <170fa0d20611071218t3c145ef9i5413e432597d78a5@mail.gmail.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 862 Lines: 19 On Tue, Nov 07, 2006 at 03:18:08PM -0500, Mike Snitzer wrote: > Srinivasa's description of the patch just speaks to how freeze_bdev > and thaw_bdev are used by DM but completely skips justification for > switching from mutex to semaphore. Why is it beneficial and/or > necessary to use a semaphore instead of a mutex here? This used to be a semaphore; someone changed it to a mutex; we started getting device-mapper bug reports from people because the usage breaks the stated semantics for a mutex; this patch puts things back while we consider if there's a better way of doing things. 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/