[PATCH AUTOSEL 6.0 23/44] scsi: ibmvfc: Avoid path failures during live migration

From: Sasha Levin
Date: Fri Nov 18 2022 - 21:14:01 EST


From: Brian King <brking@xxxxxxxxxxxxxxxxxx>

[ Upstream commit 62fa3ce05d5d73c5eccc40b2db493f55fecfc446 ]

Fix an issue reported when performing a live migration when multipath is
configured with a short fast fail timeout of 5 seconds and also to have
no_path_retry set to fail. In this scenario, all paths would go into the
devloss state while the ibmvfc driver went through discovery to log back
in. On a loaded system, the discovery might take longer than 5 seconds,
which was resulting in all paths being marked failed, which then resulted
in a read only filesystem.

This patch changes the migration code in ibmvfc to avoid deleting rports at
all in this scenario, so we avoid losing all paths.

Signed-off-by: Brian King <brking@xxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221026181356.148517-1-brking@xxxxxxxxxxxxxxxxxx
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/scsi/ibmvscsi/ibmvfc.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index 00684e11976b..1a0c0b7289d2 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -708,8 +708,13 @@ static void ibmvfc_init_host(struct ibmvfc_host *vhost)
memset(vhost->async_crq.msgs.async, 0, PAGE_SIZE);
vhost->async_crq.cur = 0;

- list_for_each_entry(tgt, &vhost->targets, queue)
- ibmvfc_del_tgt(tgt);
+ list_for_each_entry(tgt, &vhost->targets, queue) {
+ if (vhost->client_migrated)
+ tgt->need_login = 1;
+ else
+ ibmvfc_del_tgt(tgt);
+ }
+
scsi_block_requests(vhost->host);
ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_INIT);
vhost->job_step = ibmvfc_npiv_login;
@@ -3235,9 +3240,12 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost,
/* We need to re-setup the interpartition connection */
dev_info(vhost->dev, "Partition migrated, Re-enabling adapter\n");
vhost->client_migrated = 1;
+
+ scsi_block_requests(vhost->host);
ibmvfc_purge_requests(vhost, DID_REQUEUE);
- ibmvfc_link_down(vhost, IBMVFC_LINK_DOWN);
+ ibmvfc_set_host_state(vhost, IBMVFC_LINK_DOWN);
ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_REENABLE);
+ wake_up(&vhost->work_wait_q);
} else if (crq->format == IBMVFC_PARTNER_FAILED || crq->format == IBMVFC_PARTNER_DEREGISTER) {
dev_err(vhost->dev, "Host partner adapter deregistered or failed (rc=%d)\n", crq->format);
ibmvfc_purge_requests(vhost, DID_ERROR);
--
2.35.1