From: Lukas Czerner Subject: Re: [dm-devel] do not disable ext4 discards on first discard failure? [was: Re: dm snapshot: ignore discards issued to the snapshot-origin target] Date: Wed, 4 May 2011 19:02:06 +0200 (CEST) Message-ID: References: <20110413224025.GA18589@redhat.com> <20110413234854.GA19793@redhat.com> <20110426173213.GA19604@redhat.com> <20110428001912.GA14659@redhat.com> <20110428075355.GA2190@infradead.org> <20110428205935.GA24979@redhat.com> <20110429122454.GL32370@agk-dp.fab.redhat.com> <20110429122906.GA7381@infradead.org> <4DBACB23.80607@redhat.com> <20110504163317.GA17529@thunk.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Eric Sandeen , Christoph Hellwig , Lukas Czerner , Mike Snitzer , dm-devel@redhat.com, DarkNovaNick@gmail.com, linux-lvm@redhat.com, linux-ext4@vger.kernel.org To: "Ted Ts'o" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:15529 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751295Ab1EDRCW (ORCPT ); Wed, 4 May 2011 13:02:22 -0400 In-Reply-To: <20110504163317.GA17529@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, 4 May 2011, Ted Ts'o wrote: > On Fri, Apr 29, 2011 at 09:28:51AM -0500, Eric Sandeen wrote: > > On 4/29/11 7:29 AM, Christoph Hellwig wrote: > > > FYI, that disable discard on failure seems to be an ext4 special and no > > > one else picked up that stupid idea. If ext4 wants to misbehave for > > > that just let them.. > > > > It was my "stupid idea," and I'm ok with reverting it ;) > > I think I forgot to send the patch out, but it's been reverted in the > ext4 master branch, commit id: d9f34504e695. It's more than a revert, > actually, since I also dropped error checking for FITRIM. Otherwise > an attempt to use FITRIM would stop after hitting the first dm region > that didn't support discards. > > - Ted > However I would very much like to change blkdev_issue_discard() not NOT return EOPNOTSUPP if QUEUE_FLAG_DISCARD is set, this way we can rely on EOPNOTSUPP saying really that it is NOT supported. Regardless on ext4 change. I will send a patch for it, if you guy agree. Also consider BLKDISCARD which is now broken and this change will fix that! Thanks! -Lukas