From: Eric Sandeen Subject: Re: [linux-lvm] do not disable ext4 discards on first discard failure? [was: Re: dm snapshot: ignore discards issued to the snapshot-origin target] Date: Thu, 28 Apr 2011 18:01:18 -0500 Message-ID: <4DB9F1BE.7090208@redhat.com> References: <20110412234706.GA11244@redhat.com> <20cf301cbef67d323104a0c2ff52@google.com> <20110413224025.GA18589@redhat.com> <20110413234854.GA19793@redhat.com> <20110426173213.GA19604@redhat.com> <20110428001912.GA14659@redhat.com> <20110428075355.GA2190@infradead.org> <20110428205935.GA24979@redhat.com> <4DB9DBF1.9060901@redhat.com> <20110428225945.GG32370@agk-dp.fab.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: LVM general discussion and development , Mike Snitzer , Christoph Hellwig , dm-devel@redhat.com, linux-ext4@vger.kernel.or Return-path: Received: from mx1.redhat.com ([209.132.183.28]:38389 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756565Ab1D1XBa (ORCPT ); Thu, 28 Apr 2011 19:01:30 -0400 In-Reply-To: <20110428225945.GG32370@agk-dp.fab.redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 4/28/11 5:59 PM, Alasdair G Kergon wrote: > On Thu, Apr 28, 2011 at 04:28:17PM -0500, Eric Sandeen wrote: >> I still think that concats of floppies, usb disks, and ssds should be rare, so I'm less concerned about that ;) > > It's the 'undefined' cases that cause us the trouble though: we do have > to return something and I prefer to work with defined and documented > behaviour, rather than pretending something is 'undefined' or > 'unimportant' and later finding people relied on its actual behaviour. If you are saying that a target should return EOPNOTSUPP when it does not support the operation, then we are in violent agreement. :) -Eric > Alasdair