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dm mpath: change attached scsi_dh

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When specifying a different hardware handler via multipath
features we should be able to override the built-in defaults.

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.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Hannes Reinecke 2009-06-22 10:12:11 +01:00 committed by Alasdair G Kergon
parent 4d89b7b4e4
commit a0cf7ea954
1 changed files with 13 additions and 2 deletions
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15
drivers/md/dm-mpath.c
View file

@ -597,9 +597,20 @@ 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;
}