From db591bd2d7ca4d0fa3b770972f30646394ccbbe3 Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@suse.de>
Date: Wed, 22 Jul 2020 12:51:59 +0200
Subject: [PATCH 2/4] scsi: scsi_dh_alua: return BLK_STS_AGAIN for ALUA transitioning
state
Git-commit: 268940b80fa4096397fd0a28e6ad807e64120215
Patch-mainline: v5.11-rc1
References: bsc#1165933, bsc#1171000
When the ALUA state indicates transitioning we should not retry the command
immediately, but rather complete the command with BLK_STS_AGAIN to signal
the completion handler that it might be retried. This allows multipathing
to redirect the command to another path if possible, and avoid stalls
during lengthy transitioning times.
Link: https://lore.kernel.org/r/20200930080256.90964-3-hare@suse.de
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Martin Wilck <mwilck@suse.com>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 2 +-
drivers/scsi/scsi_lib.c | 5 +++++
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index f32da0ca529e..9e8d32d01d91 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -1091,7 +1091,7 @@ static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req)
case SCSI_ACCESS_STATE_LBA:
return BLK_STS_OK;
case SCSI_ACCESS_STATE_TRANSITIONING:
- return BLK_STS_RESOURCE;
+ return BLK_STS_AGAIN;
default:
req->rq_flags |= RQF_QUIET;
return BLK_STS_IOERR;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 2e8899654fe7..90c62bb9441e 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1714,6 +1714,11 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
scsi_device_blocked(sdev))
ret = BLK_STS_DEV_RESOURCE;
break;
+ case BLK_STS_AGAIN:
+ scsi_req(req)->result = DID_BUS_BUSY << 16;
+ if (req->rq_flags & RQF_DONTPREP)
+ scsi_mq_uninit_cmd(cmd);
+ break;
default:
if (unlikely(!scsi_device_online(sdev)))
scsi_req(req)->result = DID_NO_CONNECT << 16;
--
2.16.4