[PATCH] scsi_dh_alua: mark port group as failed after ALUA transitioning timeout

[Hannes Reinecke <hare@suse.de>]

When ALUA transitioning timeout triggers the path group state must
be considered invalid. So add a new flag ALUA_PG_FAILED to indicate
that the path state isn't necessarily valid, and keep the existing
path state until we get a valid response from a RTPG.

Cc: Brian Bunker <brian@purestorage.com>
Cc: Martin Wilck <mwilck@suse.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 24 +++++++---------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 1d9be771f3ee..6921490a5e65 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -49,6 +49,7 @@
 #define ALUA_PG_RUN_RTPG		0x10
 #define ALUA_PG_RUN_STPG		0x20
 #define ALUA_PG_RUNNING			0x40
+#define ALUA_PG_FAILED			0x80
 
 static uint optimize_stpg;
 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
@@ -420,7 +421,7 @@ static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
 			 */
 			rcu_read_lock();
 			pg = rcu_dereference(h->pg);
-			if (pg)
+			if (pg && !(pg->flags & ALUA_PG_FAILED))
 				pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 			rcu_read_unlock();
 			alua_check(sdev, false);
@@ -694,7 +695,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 
  skip_rtpg:
 	spin_lock_irqsave(&pg->lock, flags);
-	if (transitioning_sense)
+	if (transitioning_sense && !(pg->flags & ALUA_PG_FAILED))
 		pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 
 	if (group_id_old != pg->group_id || state_old != pg->state ||
@@ -718,23 +719,10 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 			pg->interval = ALUA_RTPG_RETRY_DELAY;
 			err = SCSI_DH_RETRY;
 		} else {
-			struct alua_dh_data *h;
-
-			/* Transitioning time exceeded, set port to standby */
+			/* Transitioning time exceeded, mark pg as failed */
 			err = SCSI_DH_IO;
-			pg->state = SCSI_ACCESS_STATE_STANDBY;
+			pg->flags |= ALUA_PG_FAILED;
 			pg->expiry = 0;
-			rcu_read_lock();
-			list_for_each_entry_rcu(h, &pg->dh_list, node) {
-				if (!h->sdev)
-					continue;
-				h->sdev->access_state =
-					(pg->state & SCSI_ACCESS_STATE_MASK);
-				if (pg->pref)
-					h->sdev->access_state |=
-						SCSI_ACCESS_STATE_PREFERRED;
-			}
-			rcu_read_unlock();
 		}
 		break;
 	case SCSI_ACCESS_STATE_OFFLINE:
@@ -746,6 +734,8 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 		/* Useable path if active */
 		err = SCSI_DH_OK;
 		pg->expiry = 0;
+		/* RTPG succeeded, clear ALUA_PG_FAILED */
+		pg->flags &= ~ALUA_PG_FAILED;
 		break;
 	}
 	spin_unlock_irqrestore(&pg->lock, flags);
-- 
2.29.2