From 7a3ad3920de780e3da1dacabe3c0abcd5b260655 Mon Sep 17 00:00:00 2001 From: "Stewart, Sean" Date: Thu, 4 Apr 2013 14:54:47 +0000 Subject: [PATCH] [SCSI] scsi_dh_alua: Add module parameter to allow failover to non preferred path without STPG Resending with requested rewording of the parameter description. Currently ALUA device handler sends STPG command during failover and failback. Failover can be optimized by implicit failover (by not to sending STPG command), when 1 is passed as hwhandler parameter in multipath.conf. ex "2 alua 1". We may need to pass the parameter through module param for alua device handler to optimize failover if incase retain_attached_hwhandler set in multipath.conf and hwhandler is set with non-tpgs device handler ex: '1 rdac'. [jejb: fix up whitespace and other issues] Signed-off-by: Vijay Chauhan Signed-off-by: Sean Stewart Acked-by: Hannes Reinecke Signed-off-by: James Bottomley --- drivers/scsi/device_handler/scsi_dh_alua.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index 6648ffb..68adb89 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -712,6 +712,10 @@ static int alua_set_params(struct scsi_device *sdev, const char *params) return result; } +static uint optimize_stpg; +module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR); +MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0."); + /* * alua_activate - activate a path * @sdev: device on the path to be activated @@ -733,6 +737,9 @@ static int alua_activate(struct scsi_device *sdev, if (err != SCSI_DH_OK) goto out; + if (optimize_stpg) + h->flags |= ALUA_OPTIMIZE_STPG; + if (h->tpgs & TPGS_MODE_EXPLICIT) { switch (h->state) { case TPGS_STATE_NONOPTIMIZED: -- 2.7.4