linux-kernel - [PATCH AUTOSEL 4.9 08/18] scsi: scsi_dh_alua: handle RTPG sense code correctly during state transitions

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Message-Id: <20191030155700.10748-8-sashal@kernel.org>
Date:   Wed, 30 Oct 2019 11:56:50 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Hannes Reinecke <hare@...e.com>,
        Laurence Oberman <loberman@...hat.com>,
        "Ewan D . Milne" <emilne@...hat.com>,
        Bart Van Assche <bvanassche@....org>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>, linux-scsi@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 08/18] scsi: scsi_dh_alua: handle RTPG sense code correctly during state transitions

From: Hannes Reinecke <hare@...e.com>

[ Upstream commit b6ce6fb121a655aefe41dccc077141c102145a37 ]

Some arrays are not capable of returning RTPG data during state
transitioning, but rather return an 'LUN not accessible, asymmetric access
state transition' sense code. In these cases we can set the state to
'transitioning' directly and don't need to evaluate the RTPG data (which we
won't have anyway).

Link: https://lore.kernel.org/r/20191007135701.32389-1-hare@suse.de
Reviewed-by: Laurence Oberman <loberman@...hat.com>
Reviewed-by: Ewan D. Milne <emilne@...hat.com>
Reviewed-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Hannes Reinecke <hare@...e.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 98787588247bf..60c288526355a 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -527,6 +527,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 	unsigned int tpg_desc_tbl_off;
 	unsigned char orig_transition_tmo;
 	unsigned long flags;
+	bool transitioning_sense = false;
 
 	if (!pg->expiry) {
 		unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
@@ -571,13 +572,19 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 			goto retry;
 		}
 		/*
-		 * Retry on ALUA state transition or if any
-		 * UNIT ATTENTION occurred.
+		 * If the array returns with 'ALUA state transition'
+		 * sense code here it cannot return RTPG data during
+		 * transition. So set the state to 'transitioning' directly.
 		 */
 		if (sense_hdr.sense_key == NOT_READY &&
-		    sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
-			err = SCSI_DH_RETRY;
-		else if (sense_hdr.sense_key == UNIT_ATTENTION)
+		    sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
+			transitioning_sense = true;
+			goto skip_rtpg;
+		}
+		/*
+		 * Retry on any other UNIT ATTENTION occurred.
+		 */
+		if (sense_hdr.sense_key == UNIT_ATTENTION)
 			err = SCSI_DH_RETRY;
 		if (err == SCSI_DH_RETRY &&
 		    pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
@@ -665,7 +672,11 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 		off = 8 + (desc[7] * 4);
 	}
 
+ skip_rtpg:
 	spin_lock_irqsave(&pg->lock, flags);
+	if (transitioning_sense)
+		pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
+
 	sdev_printk(KERN_INFO, sdev,
 		    "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 		    ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
-- 
2.20.1