From: Hannes Reinecke <hare@suse.de>
Subject: Disable partitions scan for multipathed devices
References: bnc#402922,bnc#514767
Patch-mainline: not yet, <hare: reworked by mwilck, will update, Oct 4, 2017>

When multipath devices are being used as disks for VM Guests
any partition scanning / setup should be done within the VM Guest,
not from host. So we need to switch off partitions scanning via
kpartx there.
For this I've implemented a new feature 'no_partitions' which
just serves as a notifier to kpartx to _not_ create partitions
on these devices.

Patch ported to SLES11.

[Update jeffm: Upstream commit 518257b13276 switched to using a flags
 field for multipath state, so we can use that now.]

Signed-off-by: Hannes Reinecke <hare@suse.de>

---
 drivers/md/dm-mpath.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -126,6 +126,7 @@ static void activate_path(struct work_st
 #define MPATHF_PG_INIT_DISABLED 4		/* pg_init is not currently allowed */
 #define MPATHF_PG_INIT_REQUIRED 5		/* pg_init needs calling? */
 #define MPATHF_PG_INIT_DELAY_RETRY 6		/* Delay pg_init retry? */
+#define MPATHF_NO_PARTITIONS 31			/* Don't scan partition table */
 
 /*-----------------------------------------------
  * Allocation routines
@@ -859,6 +860,10 @@ static int parse_features(struct dm_arg_
 			continue;
 		}
 
+		if (!strcasecmp(arg_name, "no_partitions")) {
+			set_bit(MPATHF_NO_PARTITIONS, &m->flags);
+			continue;
+		}
 		if (!strcasecmp(arg_name, "pg_init_retries") &&
 		    (argc >= 1)) {
 			r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
@@ -1454,13 +1459,16 @@ static void multipath_status(struct dm_t
 		DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
 			      (m->pg_init_retries > 0) * 2 +
 			      (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
+			      test_bit(MPATHF_NO_PARTITIONS, &m->flags) +
 			      test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
 			      (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
 
 		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
 			DMEMIT("queue_if_no_path ");
 		if (m->pg_init_retries)
 			DMEMIT("pg_init_retries %u ", m->pg_init_retries);
+		if (test_bit(MPATHF_NO_PARTITIONS, &m->flags))
+			DMEMIT("no_partitions ");
 		if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
 			DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
 		if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))