From a490a07a67b7a37f588021410e06b721a752fc34 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Thu, 24 Mar 2011 13:54:33 +0000
Subject: [PATCH] dm mpath: allow table load with no priority groups
This patch adjusts the multipath target to allow a table with both 0
priority groups and 0 for the initial priority group number.
If any mpath device is held open when all paths in the last priority
group have failed, userspace multipathd will attempt to reload the
associated DM table to reflect the fact that the device no longer has
any priority groups. But the reload attempt always failed because the
multipath target did not allow 0 priority groups.
All multipath target messages related to priority group (enable_group,
disable_group, switch_group) will handle a priority group of 0 (will
cause error).
When reloading a multipath table with 0 priority groups, userspace
multipathd must be updated to specify an initial priority group number
of 0 (rather than 1).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: Babu Moger <babu.moger@lsi.com>
Acked-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
drivers/md/dm-mpath.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 52f0de39463214..a550a057d991bc 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -844,8 +844,8 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
{
/* target parameters */
static struct param _params[] = {
- {1, 1024, "invalid number of priority groups"},
- {1, 1024, "invalid initial priority group number"},
+ {0, 1024, "invalid number of priority groups"},
+ {0, 1024, "invalid initial priority group number"},
};
int r;
@@ -879,6 +879,13 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
if (r)
goto bad;
+ if ((!m->nr_priority_groups && next_pg_num) ||
+ (m->nr_priority_groups && !next_pg_num)) {
+ ti->error = "invalid initial priority group";
+ r = -EINVAL;
+ goto bad;
+ }
+
/* parse the priority groups */
while (as.argc) {
struct priority_group *pg;
@@ -1415,7 +1422,7 @@ static int multipath_status(struct dm_target *ti, status_type_t type,
else if (m->current_pg)
pg_num = m->current_pg->pg_num;
else
- pg_num = 1;
+ pg_num = (m->nr_priority_groups ? 1 : 0);
DMEMIT("%u ", pg_num);
--
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