From: Martin Wilck martin.wilck@suse.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=yoidHYD7tG8XdMHEBJTBraVEo...
Co-developed-by: Rajashekhar M A rajs@netapp.com Co-developed-by: Hannes Reinecke hare@suse.de Signed-off-by: Hannes Reinecke hare@suse.de Signed-off-by: Martin Wilck martin.wilck@suse.com Link: https://lore.kernel.org/r/20240514140344.19538-1-mwilck@suse.com Reviewed-by: Damien Le Moal dlemoal@kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Mike Christie michael.christie@oracle.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.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)