From: Lukas Czerner Subject: Re: [PATCH 1/2] Add discard/nodiscard mount option for ext3 Date: Mon, 12 Jul 2010 18:05:58 +0200 (CEST) Message-ID: References: <1278508727-29135-1-git-send-email-lczerner@redhat.com> <1278508727-29135-2-git-send-email-lczerner@redhat.com> <20100712151921.GA19433@atrey.karlin.mff.cuni.cz> <4C3B3CDE.9060505@redhat.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Jan Kara , Lukas Czerner , linux-ext4@vger.kernel.org, jmoyer@redhat.com, eshishki@redhat.com, sandeen@redhat.com To: Ric Wheeler Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55841 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753141Ab0GLQGE (ORCPT ); Mon, 12 Jul 2010 12:06:04 -0400 In-Reply-To: <4C3B3CDE.9060505@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, 12 Jul 2010, Ric Wheeler wrote: > On 07/12/2010 11:19 AM, Jan Kara wrote: > > > Those mount option has the same meaning as in ext4 file system. It > > > provide a way to enable/disable file system's trim support. The trim > > > support is off by default, thus nodiscard option is not actually > > > necessary. > > I kind of miss why ext3 should have a 'discard' mount option. When > > user calls DISCARD ioctl on the filesystem, then he probably wants > > discard to be performed. > > > > Honza > > > > Sorry I misunderstood your original question. > > One reason that you might want to have a "discard" option is to allow a system > admin to mount without barriers to protect flaky hardware (we have had some > mixed results for example). As you say, the user probably wants to have the > ioctl do the discard and should be reasonable for doing it only on solid > devices, The question is what in does on device other than SSD. I know it does not harm the deivce, but is there some kernel logic preventing the trim command to be send to device that does not support it ? I hope so. -Lukas > > Regards, > > Ric >