From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 25 Sep 2017 17:07:20 +0200 From: Christoph Hellwig To: Hannes Reinecke Cc: Christoph Hellwig , Jens Axboe , Keith Busch , Sagi Grimberg , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, "Martin K. Petersen" Subject: Re: [PATCH 8/9] nvme: implement multipath access to nvme subsystems Message-ID: <20170925150720.GA11055@lst.de> References: <20170925134031.10548-1-hch@lst.de> <20170925134031.10548-9-hch@lst.de> <1fb2f077-151a-b02f-2bf5-329ef5951a68@suse.de> <20170925135007.GA9725@lst.de> <55a10165-ac3c-f808-b031-6d907c314c30@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <55a10165-ac3c-f808-b031-6d907c314c30@suse.de> List-ID: On Mon, Sep 25, 2017 at 04:05:17PM +0200, Hannes Reinecke wrote: > On 09/25/2017 03:50 PM, Christoph Hellwig wrote: > > On Mon, Sep 25, 2017 at 03:47:43PM +0200, Hannes Reinecke wrote: > >> Can't we make the multipath support invisible to the host? > >> IE check the shared namespaces before creating the device node, and just > >> move them under the existing namespaces if one exists? > > > > That was what my first version did, but various people talked me > > out of it. Unfortunately just multiplexing breaks a few things, > > including the userspace passthrough ioctls. > > > Care to give some specifics? > How would userspace passthrough be affected? Because specific commands will have to go to the right controller and not just any avaiable controller. If we only expose a single node for multipath there is no way to chose the specific one. From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@lst.de (Christoph Hellwig) Date: Mon, 25 Sep 2017 17:07:20 +0200 Subject: [PATCH 8/9] nvme: implement multipath access to nvme subsystems In-Reply-To: <55a10165-ac3c-f808-b031-6d907c314c30@suse.de> References: <20170925134031.10548-1-hch@lst.de> <20170925134031.10548-9-hch@lst.de> <1fb2f077-151a-b02f-2bf5-329ef5951a68@suse.de> <20170925135007.GA9725@lst.de> <55a10165-ac3c-f808-b031-6d907c314c30@suse.de> Message-ID: <20170925150720.GA11055@lst.de> On Mon, Sep 25, 2017@04:05:17PM +0200, Hannes Reinecke wrote: > On 09/25/2017 03:50 PM, Christoph Hellwig wrote: > > On Mon, Sep 25, 2017@03:47:43PM +0200, Hannes Reinecke wrote: > >> Can't we make the multipath support invisible to the host? > >> IE check the shared namespaces before creating the device node, and just > >> move them under the existing namespaces if one exists? > > > > That was what my first version did, but various people talked me > > out of it. Unfortunately just multiplexing breaks a few things, > > including the userspace passthrough ioctls. > > > Care to give some specifics? > How would userspace passthrough be affected? Because specific commands will have to go to the right controller and not just any avaiable controller. If we only expose a single node for multipath there is no way to chose the specific one.