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.
Signed-off-by: Hannes Reinecke <h...@suse.de>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 33 ++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c
b/drivers/scsi/device_handler/scsi_dh_alua.c
index 2fa985e..3c6b365 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -467,6 +467,30 @@ static int alua_check_sense(struct scsi_device *sdev,
}
/*
+ * 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 occured, 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.
*
@@ -725,7 +749,16 @@ static void alua_rtpg_work(struct work_struct *work)
return;
}
if (pg->flags & ALUA_PG_RUN_RTPG) {
+ int state = pg->state;
spin_unlock_irqrestore(&pg->rtpg_lock, flags);
+ if (state == TPGS_STATE_TRANSITIONING) {
+ if (alua_tur(sdev) == SCSI_DH_RETRY) {
+ queue_delayed_work(pg->work_q, &pg->rtpg_work,
+ pg->interval * HZ);
+ return;
+ }
+ /* Send RTPG on failure or if TUR indicates SUCCESS */
+ }
err = alua_rtpg(sdev, pg);
if (err == SCSI_DH_RETRY) {
queue_delayed_work(pg->work_q, &pg->rtpg_work,
--
1.8.5.6
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