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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 <bart.vanassche@sandisk.com>
Reviewed-by: Ewan Milne <emilne@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Hannes Reinecke 2016-02-19 09:17:15 +01:00 committed by Martin K. Petersen
parent c57168a1e1
commit 9d2c303952
1 changed files with 38 additions and 0 deletions
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38
drivers/scsi/device_handler/scsi_dh_alua.c
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@ -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) {