Re: Bugs in multipath scsi in 4.3-rc2

[Christoph Hellwig <hch@lst.de>]

On Fri, Oct 02, 2015 at 06:44:57AM -0700, James Bottomley wrote:
> I think I prefer restoring that to having to build in every dh module to
> get them to work.  If we take your proposed fix for the sync module load
> in the current scheme, any non-built in modules would never attach, so
> we'd be moving towards the conclusion that *every* device handler has to
> be non-modular.

You don't need to build every module in to make it work.  In 4.2 and earlier
we already only auto load modules when dm-multipath explicitly attaches
to them.  That will still work in 4.3+.  In fact we will now autoload
when activating through sysfs as well.  With the change I sent to Paul
we still won't autoload at scan time, which would be really useful to have,
but wasn't implemented previously.

> Skimming the code it looks like dh should be using the driver binding
> model rather than reinventing it.  That would decouple it better and
> make sure binding happened regardless of when the module was loaded.

I tried this early on but gave up because I ran into too many problems.
I can try to give it a spin again.