Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992492AbbHHQUm (ORCPT ); Sat, 8 Aug 2015 12:20:42 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:26746 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946683AbbHHQUk (ORCPT ); Sat, 8 Aug 2015 12:20:40 -0400 To: Mike Snitzer Cc: Ming Lin , device-mapper development , Ming Lei , Christoph Hellwig , Alasdair Kergon , Lars Ellenberg , Philip Kelleher , Joshua Morris , Christoph Hellwig , Kent Overstreet , Nitin Gupta , Ming Lin , Oleg Drokin , Al Viro , Jens Axboe , Andreas Dilger , Geoff Levand , Jiri Kosina , lkml , Jim Paris , Minchan Kim , Dongsu Park , drbd-user@lists.linbit.com Subject: Re: [dm-devel] [PATCH v5 01/11] block: make generic_make_request handle arbitrarily sized bios From: "Martin K. Petersen" Organization: Oracle References: <1436168690-32102-1-git-send-email-mlin@kernel.org> <20150731192337.GA8907@redhat.com> <20150731213831.GA16464@redhat.com> <1438412290.26596.14.camel@hasee> <20150801163356.GA21478@redhat.com> Date: Sat, 08 Aug 2015 12:19:20 -0400 In-Reply-To: <20150801163356.GA21478@redhat.com> (Mike Snitzer's message of "Sat, 1 Aug 2015 12:33:57 -0400") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1229 Lines: 29 >>>>> "Mike" == Mike Snitzer writes: Mike> This will translate to all intermediate layers that might split Mike> discards needing to worry about granularity/alignment too Mike> (e.g. how dm-thinp will have to care because it must generate Mike> discard mappings with associated bios based on how blocks were Mike> mapped to thinp). The fundamental issue here is that alignment and granularity should never, ever have been enforced at the top of the stack. Horrendous idea from the very beginning. For the < handful of braindead devices that get confused when you do partial or misaligned blocks we should have had a quirk that did any range adjusting at the bottom in sd_setup_discard_cmnd(). There's a reason I turned discard_zeroes_data off for UNMAP! Wrt. the range size I don't have a problem with capping at the 32-bit bi_size limit. We probably don't want to send commands much bigger than that anyway. -- Martin K. Petersen Oracle Linux Engineering -- 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/