From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933137AbcALQvW (ORCPT ); Tue, 12 Jan 2016 11:51:22 -0500 Received: from mail-yk0-f173.google.com ([209.85.160.173]:34224 "EHLO mail-yk0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750961AbcALQvV (ORCPT ); Tue, 12 Jan 2016 11:51:21 -0500 MIME-Version: 1.0 In-Reply-To: <56952E17.5010007@hpe.com> References: <1450393200-6802-1-git-send-email-toshi.kani@hpe.com> <1450427687.11503.14.camel@kernel.org> <1450451737.20148.121.camel@hpe.com> <1450464730.10450.14.camel@hpe.com> <1452610938.19330.66.camel@hpe.com> <56952E17.5010007@hpe.com> Date: Tue, 12 Jan 2016 08:51:20 -0800 Message-ID: Subject: Re: [PATCH] BTT: Change nd_btt_arena_is_valid() to verify UUID From: Dan Williams To: Linda Knippers Cc: Toshi Kani , Vishal Verma , "linux-kernel@vger.kernel.org" , micah.parrish@hpe.com, "linux-nvdimm@lists.01.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 12, 2016 at 8:47 AM, Linda Knippers wrote: > On 1/12/2016 11:38 AM, Dan Williams wrote: >> On Tue, Jan 12, 2016 at 7:02 AM, Toshi Kani wrote: >>> On Fri, 2015-12-18 at 14:23 -0800, Dan Williams wrote: >>>> On Fri, Dec 18, 2015 at 10:52 AM, Toshi Kani wrote: >>>>> On Fri, 2015-12-18 at 09:54 -0800, Dan Williams wrote: >>>>>> On Fri, Dec 18, 2015 at 7:15 AM, Toshi Kani >>>>>> wrote: >>>>>>> On Fri, 2015-12-18 at 01:34 -0700, Vishal Verma wrote: >>>>>>>> Also, I wonder if this problem is solved by using libndctl to >>>>>>>> manage >>>>>>>> BTTs. >>>>>>> >>>>>>> I have not tested with libndctl yet, but I think our bind/unbind >>>>>>> scripts do the same procedures. >>>>>> >>>>>> We loop through all combinations of sector size in our unit test. If >>>>>> you want to change the sector size the expectation is that the >>>>>> namespace is destroyed and fully re-created, especially due to the >>>>>> fact that changing sector size invalidates all data on the namespace. >>>>>> >>>>>> See: https://github.com/pmem/ndctl/blob/master/lib/test-libndctl.c >>>>> >>>>> The parent_uuid is not set on our NVDIMM-N systems. I do not see >>>>> 'uuid' file under sysfs 'namespaceX.X' per namespace_visible(), either. >>>>> This concept of creating/destroying a namespace is a bit foreign to us >>>>> since we've never needed to do. Can you elaborate how it's supposed to >>>>> work for NVDIMM-N? >>>>> >>>> >>>> Ugh, yes. An oversight on my part, let me give this some thought. >>>> Whatever we decide, I want the libndctl api to be identical for the >>>> two cases. >>>> >>>> I expect the simplest option is to have >>>> ndctl_namespace_disable_invalidate() destroy the btt-info block in the >>>> NVDIMM-N case. >>> >>> Do you have any update on this? If we are going to use ndctl to address >>> this issue, does it mean that we will have to use ndctl to manage BTT? >> >> This is my current proposal: >> >> https://github.com/pmem/ndctl/blob/pending/Documentation/ndctl-create-namespace.txt > > I don't really like "safe" as a mode choice. The others are "memory" and "raw". > Could the one using the BTT be "sector" or "atomic" or "btt" or something other > than "safe"? Using "safe" implies that the others aren't safe, but they are if > you use them for their intended purpose and know what you're doing. Of those alternatives I think "sector" mode is the most clear.