Hi Mike, michaelc@xxxxxxxxxxx wrote: > From: Mike Christie <michaelc@xxxxxxxxxxx> > > If you have a mixed environment of clarriions, where some > support ALAU and some support PNR, what do you put in > your multipath.conf? With this patch you do not have to worry about > it. If those modules are loaded before dm-mpath, then they > will have attached to the correct devices based on inquiry, alua commands > and parsing of data buffers (for example in scsi_dh_emc's alua check). > There is no need for the user to set that info in the multipath.conf. > And in general since all scsi_dh_modules will attach to the devices > they work for, we do not need to have users specific this. > No. The problem here is the hardware table from scsi_dh is compiled in and cannot be changed from userland. The multipath.conf OTOH is purely user-defined and, what's more, the user might have a valid reason for modifying it. (EG EMC Clariion can well be run in PNR mode even though ALUA is active, or the user might want to try ALUA on any as-of-yet unknown devices) So _not_ allowing multipath to override the device handler setting will just add to the confusion and makes error tracking even more difficult. So I would prefer the attached patch, it even save to touch device handler code at all. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Markus Rex, HRB 16746 (AG Nürnberg)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 095f77b..46d01d9 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -592,12 +592,25 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, } if (m->hw_handler_name) { - r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev), - m->hw_handler_name); + struct request_queue *q = bdev_get_queue(p->path.dev->bdev); + + r = scsi_dh_attach(q, m->hw_handler_name); + if (r == -EBUSY) { + /* + * Already attached to different hw_handler, + * try to reattach with correct one. + */ + scsi_dh_detach(q); + r = scsi_dh_attach(q, m->hw_handler_name); + } if (r < 0) { + ti->error = "error attaching hardware handler"; dm_put_device(ti, p->path.dev); goto bad; } + } else { + /* Play safe and detach hardware handler */ + scsi_dh_detach(bdev_get_queue(p->path.dev->bdev)); } r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);