Patch "scsi: core: alua: I/O errors for ALUA state transitions" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    scsi: core: alua: I/O errors for ALUA state transitions

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     scsi-core-alua-i-o-errors-for-alua-state-transitions.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5fe88021f3ab81528e0acb4e99c8e0ea11547e0f
Author: Martin Wilck <martin.wilck@xxxxxxxx>
Date:   Tue May 14 16:03:44 2024 +0200

    scsi: core: alua: I/O errors for ALUA state transitions
    
    [ 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@xxxxxxxxxx/
    [2] https://lore.kernel.org/all/CAGtn9r=kicnTDE2o7Gt5Y=yoidHYD7tG8XdMHEBJTBraVEoOCw@xxxxxxxxxxxxxx/
    
    Co-developed-by: Rajashekhar M A <rajs@xxxxxxxxxx>
    Co-developed-by: Hannes Reinecke <hare@xxxxxxx>
    Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
    Signed-off-by: Martin Wilck <martin.wilck@xxxxxxxx>
    Link: https://lore.kernel.org/r/20240514140344.19538-1-mwilck@xxxxxxxx
    Reviewed-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
    Reviewed-by: Christoph Hellwig <hch@xxxxxx>
    Reviewed-by: Mike Christie <michael.christie@xxxxxxxxxx>
    Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 0781f991e7845..f5fc8631883d5 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)




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