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=a58a935d5a1b2ad267017a68c3a1bca26226cc76 > > 2. add scsi_dh_attached_handler_name > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=7e8a74b177f17d100916b6ad415450f7c9508691 > > > 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. Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
