Tejun Heo [off-list ref] writes:

On Wed, Jan 07, 2015 at 05:02:17PM -0600, Eric W. Biederman wrote:

quoted

Ignoring namespace details for a moment. The following should be
possible with a unified hierarchy.  If it is not it is a show stopper
of a regression.

The -o SUBSYS option doesn't exist.  Jesus, at least get yourself
familiar with the basics before claiming random stuff.

Not random and I am familiar thank you very much.

I may have mistyped the manual command line configuration for specifying
which controllers appear on a mount point does not alter my point.

The old options to enable selecting controllers need to continue and
need to continue to work with a unified hierarchy.

Anything else is a gratuitious regression.

Eric