> -----Original Message----- > From: Mike Snitzer [mailto:snitzer@xxxxxxxxxx] > Sent: Wednesday, August 08, 2012 2:31 PM > To: Moger, Babu > Cc: linux-scsi; device-mapper development (dm-devel@xxxxxxxxxx) > Subject: Re: scsi_dh_rdac: Add empty set_params function to scsi_dh_rdac > > On Wed, Aug 08 2012 at 12:10pm -0400, > Moger, Babu <Babu.Moger@xxxxxxxxxx> wrote: > > > This patch adds empty set_params function to scsi_dh_rdac. > > > > This patch is required for the following features to work properly. > > 1. add retain_attached_hw_handler feature > > > > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=a58a > 935d5a1b2ad267017a68c3a1bca26226cc76 > > > > 2. add scsi_dh_attached_handler_name > > > > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=7e8 > a74b177f17d100916b6ad415450f7c9508691 > > > > > > DM layer detaches the handler if the set_params is not implemented or > fails. > > > > For example if we pass following parameters from multipath: > > > > features "1 retain_attached_hw_handler" (consider rdac as > attached_hw_handler) > > hardware_handler "2 alua 1" > > > > If the attached_hw_handler is rdac, then DM anyway tries to call > set_params on rdac. Because rdac does not > > implement set_params, scsi_dh_set_params fails and DM detaches the > handler. > > > > This patch fixes this problem. > > > > Signed-off-by: Babu Moger <babu.moger@xxxxxxxxxx> > > I think it'd be best to fix scsi_dh_set_params() so that it returns 0 if > scsi_dh->set_params is NULL. That'd avoid all scsi_dh from having to > stub out a similar set_params to return 0. > > But taking a step back, have you actually seen the problem you're saying > this patch fixes? > > This problem shouldn't exist: > drivers/md/dm-mpath.c:parse_path will free m->hw_handler_params (and > reset it to NULL) if a scsi_dh is already attached. Have a look at the > if (attached_handler_name) {} case. My bad. I was still using one of your old patches. http://www.redhat.com/archives/dm-devel/2012-June/msg00174.html Things have changed after this version. We don't have this problem with the new set of patches. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
