From 9d2c30395213166e0b5614fe97576a789864e5de Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Fri, 19 Feb 2016 09:17:15 +0100 Subject: [PATCH] scsi_dh_alua: Send TEST UNIT READY to poll for transitioning Sending a 'REPORT TARGET PORT GROUP' command is a costly operation, as the array has to gather information about all ports. So instead of using RTPG to poll for a status update when a port is in transitioning we should be sending a TEST UNIT READY, and wait for the sense code to report success. Reviewed-by: Bart Van Assche Reviewed-by: Ewan Milne Reviewed-by: Christoph Hellwig Signed-off-by: Hannes Reinecke Signed-off-by: Martin K. Petersen --- drivers/scsi/device_handler/scsi_dh_alua.c | 38 ++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index 98d87d9765ab..3d8a254607e1 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -465,6 +465,30 @@ static int alua_check_sense(struct scsi_device *sdev, return SCSI_RETURN_NOT_HANDLED; } +/* + * alua_tur - Send a TEST UNIT READY + * @sdev: device to which the TEST UNIT READY command should be send + * + * Send a TEST UNIT READY to @sdev to figure out the device state + * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING, + * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise. + */ +static int alua_tur(struct scsi_device *sdev) +{ + struct scsi_sense_hdr sense_hdr; + int retval; + + retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ, + ALUA_FAILOVER_RETRIES, &sense_hdr); + if (sense_hdr.sense_key == NOT_READY && + sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) + return SCSI_DH_RETRY; + else if (retval) + return SCSI_DH_IO; + else + return SCSI_DH_OK; +} + /* * alua_rtpg - Evaluate REPORT TARGET GROUP STATES * @sdev: the device to be evaluated. @@ -732,8 +756,22 @@ static void alua_rtpg_work(struct work_struct *work) alua_wq = kaluad_sync_wq; pg->flags |= ALUA_PG_RUNNING; if (pg->flags & ALUA_PG_RUN_RTPG) { + int state = pg->state; + pg->flags &= ~ALUA_PG_RUN_RTPG; spin_unlock_irqrestore(&pg->lock, flags); + if (state == TPGS_STATE_TRANSITIONING) { + if (alua_tur(sdev) == SCSI_DH_RETRY) { + spin_lock_irqsave(&pg->lock, flags); + pg->flags &= ~ALUA_PG_RUNNING; + pg->flags |= ALUA_PG_RUN_RTPG; + spin_unlock_irqrestore(&pg->lock, flags); + queue_delayed_work(alua_wq, &pg->rtpg_work, + pg->interval * HZ); + return; + } + /* Send RTPG on failure or if TUR indicates SUCCESS */ + } err = alua_rtpg(sdev, pg); spin_lock_irqsave(&pg->lock, flags); if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) { -- 2.20.1