From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: [RESEND PATCH 2/3] dm mpath: add 'default_hw_handler' feature Date: Wed, 11 Jul 2012 09:20:59 -0400 Message-ID: <20120711132059.GA9616@redhat.com> References: <1340735525-21083-1-git-send-email-snitzer@redhat.com> <1340735525-21083-3-git-send-email-snitzer@redhat.com> <4FEAA557.7050501@suse.de> <20120711102754.GA2095@agk-dp.fab.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120711102754.GA2095@agk-dp.fab.redhat.com> Sender: linux-scsi-owner@vger.kernel.org To: Hannes Reinecke , device-mapper development , James Bottomley , linux-scsi@vger.kernel.org List-Id: dm-devel.ids On Wed, Jul 11 2012 at 6:27am -0400, Alasdair G Kergon wrote: > On Wed, Jun 27, 2012 at 08:16:55AM +0200, Hannes Reinecke wrote: > > On 06/26/2012 08:32 PM, Mike Snitzer wrote: > > > When specifying the feature 'default_hw_handler' multipath will use > > > the currently attached hardware handler instead of trying to attach the > > > one specified during table load. If no hardware handler is attached the > > > specified hardware handler will be used. > > > > > > Leverages 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. > > > > > > Signed-off-by: Mike Snitzer > > > Tested-by: Babu Moger > > > Reviewed-by: Chandra Seetharaman > > Looks good. > > Maybe, but I'd like to see an inline explanation of what this confusing new > setting means and a better patch header that provides some motivation for this > change. > > To my eyes, the word "default" is over-used here. If I *don't* specify the new > "default" flag, surely I'll get default behaviour, won't I, by definition? And > if I do specify it, I'm asking for default behaviour too, so isn't it > redundant? "default" is in reference to the hardware handler that will get attached by the scsi_dh .match(). It has nothing to do with the userspace multipath-tool's desired handler.