Re: [PATCH] I/O errors for ALUA state transitions

alua_check_sense() checks for NOT READY / 04h 0Ah but not
UNIT ATTENTION with the same ASC/ASCQ.

Careful about updating pg->state in this case though because that
may cause subsequent I/O in the probe to fail, we didn't do this before
and we *may* only get the UA once.

-Ewan

On Wed, Sep 8, 2021 at 2:12 AM Hannes Reinecke [off-list ref] wrote:

On 9/7/21 5:59 PM, michael.christie@oracle.com wrote:

quoted

On 9/7/21 2:16 AM, Hannes Reinecke wrote:

quoted

From: Rajashekhar M A <redacted>

When a host is configured with a few LUNs and IO 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 two 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.

quoted

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

---
  drivers/scsi/scsi_error.c | 7 ++++---
  1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 03a2ff547b22..1185083105ae 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c

@@ -594,10 +594,11 @@ enum scsi_disposition scsi_check_sense(struct scsi_cmnd *scmd)
                 sshdr.asc == 0x3f && sshdr.ascq == 0x0e)
                     return NEEDS_RETRY;
             /*
-             * if the device is in the process of becoming ready, we
-             * should retry.
+             * if the device is in the process of becoming ready, or
+             * transitions between ALUA states, we should retry.
              */
-            if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
+            if ((sshdr.asc == 0x04) &&
+                (sshdr.ascq == 0x01 || sshdr.ascq == 0x0a))
                     return NEEDS_RETRY;

Why put this here instead of in alua_check_sense with the other ALUA
state transition check?

Good point. Will be updating the patch.

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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