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Message-ID: <20240617132617.2589631-1-sashal@kernel.org>
Date: Mon, 17 Jun 2024 09:25:38 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Martin Wilck <martin.wilck@...e.com>,
Rajashekhar M A <rajs@...app.com>,
Hannes Reinecke <hare@...e.de>,
Damien Le Moal <dlemoal@...nel.org>,
Christoph Hellwig <hch@....de>,
Mike Christie <michael.christie@...cle.com>,
"Martin K . Petersen" <martin.petersen@...cle.com>,
Sasha Levin <sashal@...nel.org>,
James.Bottomley@...senPartnership.com,
linux-scsi@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 01/21] scsi: core: alua: I/O errors for ALUA state transitions
From: Martin Wilck <martin.wilck@...e.com>
[ Upstream commit 10157b1fc1a762293381e9145041253420dfc6ad ]
When a host is configured with a few LUNs and I/O is running, injecting FC
faults repeatedly leads to path recovery problems. The LUNs have 4 paths
each and 3 of them come back active after say an FC fault which makes 2 of
the paths go down, instead of all 4. This happens after several iterations
of continuous FC faults.
Reason here is that we're returning an I/O error whenever we're
encountering sense code 06/04/0a (LOGICAL UNIT NOT ACCESSIBLE, ASYMMETRIC
ACCESS STATE TRANSITION) instead of retrying.
[mwilck: The original patch was developed by Rajashekhar M A and Hannes
Reinecke. I moved the code to alua_check_sense() as suggested by Mike
Christie [1]. Evan Milne had raised the question whether pg->state should
be set to transitioning in the UA case [2]. I believe that doing this is
correct. SCSI_ACCESS_STATE_TRANSITIONING by itself doesn't cause I/O
errors. Our handler schedules an RTPG, which will only result in an I/O
error condition if the transitioning timeout expires.]
[1] https://lore.kernel.org/all/0bc96e82-fdda-4187-148d-5b34f81d4942@oracle.com/
[2] https://lore.kernel.org/all/CAGtn9r=kicnTDE2o7Gt5Y=yoidHYD7tG8XdMHEBJTBraVEoOCw@mail.gmail.com/
Co-developed-by: Rajashekhar M A <rajs@...app.com>
Co-developed-by: Hannes Reinecke <hare@...e.de>
Signed-off-by: Hannes Reinecke <hare@...e.de>
Signed-off-by: Martin Wilck <martin.wilck@...e.com>
Link: https://lore.kernel.org/r/20240514140344.19538-1-mwilck@suse.com
Reviewed-by: Damien Le Moal <dlemoal@...nel.org>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Mike Christie <michael.christie@...cle.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 | 31 +++++++++++++++-------
1 file changed, 22 insertions(+), 9 deletions(-)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index a9c4a5e2ccb90..60792f257c235 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -406,28 +406,40 @@ static char print_alua_state(unsigned char state)
}
}
-static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
- struct scsi_sense_hdr *sense_hdr)
+static void alua_handle_state_transition(struct scsi_device *sdev)
{
struct alua_dh_data *h = sdev->handler_data;
struct alua_port_group *pg;
+ rcu_read_lock();
+ pg = rcu_dereference(h->pg);
+ if (pg)
+ pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
+ rcu_read_unlock();
+ alua_check(sdev, false);
+}
+
+static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
+ struct scsi_sense_hdr *sense_hdr)
+{
switch (sense_hdr->sense_key) {
case NOT_READY:
if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
/*
* LUN Not Accessible - ALUA state transition
*/
- rcu_read_lock();
- pg = rcu_dereference(h->pg);
- if (pg)
- pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
- rcu_read_unlock();
- alua_check(sdev, false);
+ alua_handle_state_transition(sdev);
return NEEDS_RETRY;
}
break;
case UNIT_ATTENTION:
+ if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
+ /*
+ * LUN Not Accessible - ALUA state transition
+ */
+ alua_handle_state_transition(sdev);
+ return NEEDS_RETRY;
+ }
if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
/*
* Power On, Reset, or Bus Device Reset.
@@ -494,7 +506,8 @@ static int alua_tur(struct scsi_device *sdev)
retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
ALUA_FAILOVER_RETRIES, &sense_hdr);
- if (sense_hdr.sense_key == NOT_READY &&
+ if ((sense_hdr.sense_key == NOT_READY ||
+ sense_hdr.sense_key == UNIT_ATTENTION) &&
sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
return SCSI_DH_RETRY;
else if (retval)
--
2.43.0
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