From a0cf7ea9549ec60988369f90e5c0f855f08abac9 Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@suse.de>
Date: Mon, 22 Jun 2009 10:12:11 +0100
Subject: [PATCH] dm mpath: change attached scsi_dh
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>
---
drivers/md/dm-mpath.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index f25bdebcb4ab01..545abcc25c42b5 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -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;
}
--
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