Re: [dm-devel] [PATCH 3/3] dm mpath: add support for using previously attached scsi_dh

[Mike Snitzer <snitzer redhat com>]

On Tue, May 08 2012 at  2:22am -0400,
Hannes Reinecke <hare suse de> wrote:

> On 05/08/2012 05:19 AM, Mike Snitzer wrote:
> > Use the previously attached scsi_dh if "default" is provided as the
> > hardware handler name (the new 'use_default_hw_handler' flag is set in
> > the multipath structure).
> > 
> > Leverage scsi_dh_attach's ability to increment the scsi_dh's reference
> > count if the same scsi_dh name is provided when attaching -- currently
> > attached scsi_dh name is determined with scsi_dh_attached_handler_name.
> > 
> Not sure it that's the correct way.
> 
> Using 'default' as the hardware handler name has the drawback that
> the original information (ie the original hardware handler name)
> is lost.

BTW, on this point: How is the original handler's name lost with my
patches?  I set m->hw_handler_name to the original (aka attached)
handler's name (as returned scsi_dh_attached_handler_name).

"default" is only used as a key to trigger the use of the attached
handler (it causes m->use_default_hw_handler to be set).

Was my description or code somehow unclear?  Guess so... otherwise I'd
not be clarifying this... unfortunately I'm not seeing where I fell
short.

Mike