From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:60290 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750784AbdAWO6L (ORCPT ); Mon, 23 Jan 2017 09:58:11 -0500 Date: Mon, 23 Jan 2017 09:57:52 -0500 From: Josef Bacik Subject: Re: [PATCH 4/4] nbd: add a nbd-control interface To: Greg KH CC: , , , , Message-ID: <1485183472.21123.0@smtp.office365.com> In-Reply-To: <20170123145212.GA19582@kroah.com> References: <1484949412-6903-1-git-send-email-jbacik@fb.com> <1484949412-6903-4-git-send-email-jbacik@fb.com> <20170121090531.GB27048@kroah.com> <1485182528.9861.22@smtp.office365.com> <20170123145212.GA19582@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Mon, Jan 23, 2017 at 9:52 AM, Greg KH wrote: > On Mon, Jan 23, 2017 at 09:42:08AM -0500, Josef Bacik wrote: >> >> >> On Sat, Jan 21, 2017 at 4:05 AM, Greg KH >> wrote: >> > On Fri, Jan 20, 2017 at 04:56:52PM -0500, Josef Bacik wrote: >> > > This patch mirrors the loop back device behavior with a few >> > > changes. First >> > > there is no DEL operation as NBD doesn't get as much churn as >> loop >> > > devices do. >> > > Secondly the GET_NEXT operation can optionally create a new NBD >> > > device or not. >> > > Our infrastructure people want to not allow NBD to create new >> > > devices as it >> > > causes problems for them in containers. However allow this to >> be >> > > optional as >> > > things like the OSS NBD client probably doesn't care and would >> like >> > > to just be >> > > given a device to use. >> > > >> > > Signed-off-by: Josef Bacik >> > >> > A random char device with odd ioctls? Why? There's no other >> > configuration choice you could possibly use? Where is the >> userspace >> > tool that uses this new kernel api? >> > >> > You aren't passing in structures to the ioctl, so why does this >> HAVE to >> > be an ioctl? >> >> Again, this is how loop does it so I assumed a known, regularly >> used API was >> the best bet. I can do literally anything, but these interfaces >> have to be >> used by other people, including internal people. The >> /dev/whatever-control >> is a well established way for interacting with dynamic device >> drivers (loop, >> DM, btrfs), so that's what I went with. Thanks, > > Again, please don't duplicate what loop did, we must _learn_ from > history, not repeat it :( Sure but what am I supposed to do? Have some random sysfs knobs? Thanks, Josef