[PATCH 13/13] nvme: introduce generic per-namespace chardev

[Christoph Hellwig]

On Fri, Apr 09, 2021 at 05:02:14PM +0900, Minwoo Im wrote:
> On 21-04-09 09:54:15, Christoph Hellwig wrote:
> > On Fri, Apr 09, 2021 at 04:29:01PM +0900, Minwoo Im wrote:
> > > Tested with namespace-specific admin commmand (Identify Namespace).  And
> > > it fails with invalid IOCTl because we don't have a route to the
> > > controller IOCTL for the generic chrdev.
> > 
> > Yes, that is intentional, as supporting the per-controller ioctls
> > on the per-namespace devices is a mess.
> 
> In multipath case, head blkdev is also per-namespace node which is now
> supporting the controller ioctl by nvme_find_get_live_ctrl().  Is there
> any different policy between the existing blkdev and generic device in
> the current series ? Or should be just deprecate the controller ioctl
> from the head blkdev ioctl in multipath case ?

Well, the multipath block device is supposed to be a full drop in
for the block device, including having the same name.  So I don't think
we can just deprecate it, even if that would really improve things.