Re: [PATCH] zfcp: add rports to enable scsi_add_device to work again

[Andreas Herrmann <AHERRMAN@de.ibm.com>]

On 27.08.2005 19:38 James Bottomley <jejb@steeleye.com> wrote:
 
  > > this patch fixes a severe problem with 2.6.13-rc7.
  > > 
  > > Due to recent SCSI changes it is not possible to add any
  > > LUNs to the zfcp device driver anymore. With registration
  > > of remote ports this is fixed.
  > > 
  > > Please integrate the patch in the 2.6.13 kernel or if it
  > > is already too late for this release then please integrate it
  > > in 2.6.13.1
  > > 
  > > Thanks a lot.

  > Well, OK, but your usage isn't quite optimal.  The fibre channel
  > transport class retains a list of ports per host, so your maintenance 
of
  > an identical list in zfcp_adapter duplicates this.

I know what you mean. It would be better to store all "private" zfcp
data at dd_data in fc_rport.  Unfortunately it won't fit to zfcp's
current behaviour.  The rport depends on a specific host_id. Even the
name of the rport in sys/class/fc_remote_port inherits this id. This
means if the host is deregistered and registered again the old rport
structure is useless because new host_ids are assigned. Or do I miss
something here?

The zfcp_port structure is thought to be persistent if once configured
by the user, i.e. even if the host is deregistered and registered
again the port structure is kept.

I am not sure at the moment how this can be solved with the current
fc_transport. I think it would have been better to use the WWPN of an
rport as the name in sys/class/fc_remote_port. This would be a start
to keep rport structures independent of the host_id. (Why should the
transport depend on OS assigned ids anyway? The transport has already
unique identifiers like WWPNs.)

  > However, we can put this in for now and worry about removing all of 
the
  > fc transport class duplication from zfcp later.

  > James

In any case attributes provided by an rport should be removed from the
zfcp_port structure. This is what I will do next.


Regards,

Andreas
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