From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753679AbcFGGir (ORCPT ); Tue, 7 Jun 2016 02:38:47 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:43339 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751497AbcFGGip (ORCPT ); Tue, 7 Jun 2016 02:38:45 -0400 Date: Mon, 6 Jun 2016 23:38:42 -0700 From: Christoph Hellwig To: "Martin K. Petersen" Cc: Mike Snitzer , Christoph Hellwig , Shaohua Li , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, sitsofe@yahoo.com, axboe@fb.com, Kernel-team@fb.com Subject: Re: block: correctly fallback for zeroout Message-ID: <20160607063842.GA21032@infradead.org> References: <20160526180813.GA49039@shli-mbp.local> <20160529064728.GA14383@infradead.org> <20160603035415.GA8236@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 06, 2016 at 10:32:38PM -0400, Martin K. Petersen wrote: > >>>>> "Mike" == Mike Snitzer writes: > > Mike> But hch was originally in favor of _always_ dropping EOPNOTSUPP on > Mike> the floor (that is what his commit 38f25255330 did). Then he said > Mike> he disagrees with these interfaces playing games with masking > Mike> EOPNOTSUPP -- to which you seemingly really don't agree. Unless > Mike> I'm completely misreading you. > > Userland apps rely on EOPNOTSUPP, we can't break that. Rely on what exactly? Current we return EOPNOTSUPP if the device doesn't claim to support discards, but it returns 0 if the device first claims to support it but then fails the I/O.