[PATCH V2 0/1] nvme: introduce generic per-namespace chardev

[Christoph Hellwig]

On Tue, Apr 06, 2021 at 10:35:33PM +0900, Minwoo Im wrote:
> > with e.g. fdisk, mkfs, mount, in fstab, what to specify in fstab, etc.
> > 
> > I think that there is value in reducing the confusion for regular users.
> 
> Agreed on this point.  We might have thousands of namespaces and it
> might be making confusions to users.

How does this create a confusion that it doesn't for the existing NVMe
block devices and the SCSI disk and generic devices?

Morover: why would anyone want to expose these huge numbers of
namespaces to a single host?  While larger LUN counts in SCSI are
sometimes needed for scalability reasons they aren't in NVMe.  I haven't
actually seen 4 digit namespace counts in NVMe except in synthetic
test setups yet.

> > 2) Only create the new per-ns char dev for namespaces that were rejected.
> 
> I prefer this one which is the major reason of this patch series being
> posted.

Which doesn't allow us to write portable programs just using the
char node, as now a kernel upgrade that supports a new namespace type
or feature will remove the char dev.  It also is very different from
what people expect from their SCSI and ATA setups.