Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758304AbcCCV24 (ORCPT ); Thu, 3 Mar 2016 16:28:56 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:38126 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758186AbcCCV2y (ORCPT ); Thu, 3 Mar 2016 16:28:54 -0500 Subject: Re: [GIT PULL] Block fixes for 4.5-final To: Linus Torvalds References: <20160303172516.GA24567@kernel.dk> <56D8A89E.9040200@fb.com> CC: Linux Kernel Mailing List , From: Jens Axboe Message-ID: <56D8AC92.1070802@fb.com> Date: Thu, 3 Mar 2016 14:28:50 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.54.13] X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-03-03_16:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2300 Lines: 51 On 03/03/2016 02:20 PM, Linus Torvalds wrote: > On Thu, Mar 3, 2016 at 1:11 PM, Jens Axboe wrote: >> >> It does fix a regression - the change is that NVMe now uses the block layer >> for these types of requests, and they don't have to adhere to the regular fs >> limits of sizing. Hence we broke real use cases, of (for instance) pulling >> logs off devices. Both of the referenced commits were added yesterday, not >> today. And they should have been folded, but I had already committed the >> first one. I don't think that should preclude doing it much cleaner than the >> first one. > > Why does this affect only NVMe, and not all the other drivers that > have been around forever? What is that magical case that breaks? > Details, please. Development around NVMe is a lot more active than any other driver. And that tends to drive a lot more testing, and find a lot of other bugs. That, and the fact that NVMe is still fairly young. On top of that, NVMe has been driving/utilizing some parts of blk-mq, and exercising things like surprise hot removal that haven't seen a ton of testing. >> Fair enough, I can boil it down somewhat. But honestly, the only stuff I'd >> feel comfortable pulling out now would be the lightnvm changes which aren't >> that critical due to the user base, though that's also why it would be fine >> to shove it in now. And the cgroup writeback enable, which can wait. The two >> commits referenced above could be folded, but they'd still be in the new >> pull request. >> >> So let me know if you want that, or we can proceed with the current branch, >> because most of it should really go in as-is. > > I basically want for every commit an explanation of why it's so > critical by now. I want to make you have to *think* and explain before > you send stuff at this stage, and I want to understand why each commit > is so important. > > Because really, this has been going on far too long, and this pull > request looked singularly pointless. > > No way do I want things like cgroup writeback changes outside the > merge window, for example, unless it's a major performance regression > (with numbers) or something like that. > > No way do I want any lightnvm stuff. > > No way do I want big "cleanup" patches. I'll boil it down. -- Jens Axboe