Commit 2b35865e authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Martin K. Petersen
Browse files

scsi_dh_alua: Recheck state on unit attention 



When we receive a unit attention code of 'ALUA state changed'
we should recheck the state, as it might be due to an implicit
ALUA state transition. This allows us to return NEEDS_RETRY
instead of ADD_TO_MLQUEUE, allowing to terminate the retries
after a certain time.
At the same time a workqueue item might already be queued, which
should be started immediately to avoid any delays.

Reviewed-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarHannes Reinecke <hare@suse.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 851cde99

drivers/scsi/device_handler/scsi_dh_alua.c

+55 −12
Original line number Diff line number Diff line
@@ -120,7 +120,8 @@ struct alua_queue_data { 
static void alua_rtpg_work(struct work_struct *work);

static void alua_rtpg_queue(struct alua_port_group *pg,

			    struct scsi_device *sdev,

			    struct alua_queue_data *qdata);

			    struct alua_queue_data *qdata, bool force);

static void alua_check(struct scsi_device *sdev, bool force);



static void release_port_group(struct kref *kref)

{
@@ -368,7 +369,7 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, 
	}

	if (sdev->synchronous_alua)

		pg->flags |= ALUA_SYNC_STPG;

	alua_rtpg_queue(h->pg, sdev, NULL);

	alua_rtpg_queue(h->pg, sdev, NULL, true);

	spin_unlock(&h->pg_lock);



	if (old_pg)
@@ -404,18 +405,24 @@ static int alua_check_sense(struct scsi_device *sdev, 
{

	switch (sense_hdr->sense_key) {

	case NOT_READY:

		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a)

		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {

			/*

			 * LUN Not Accessible - ALUA state transition

			 */

			return ADD_TO_MLQUEUE;

			alua_check(sdev, false);

			return NEEDS_RETRY;

		}

		break;

	case UNIT_ATTENTION:

		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)

		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {

			/*

			 * Power On, Reset, or Bus Device Reset, just retry.

			 * Power On, Reset, or Bus Device Reset.

			 * Might have obscured a state transition,

			 * so schedule a recheck.

			 */

			alua_check(sdev, true);

			return ADD_TO_MLQUEUE;

		}

		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)

			/*

			 * Device internal reset
@@ -426,16 +433,20 @@ static int alua_check_sense(struct scsi_device *sdev, 
			 * Mode Parameters Changed

			 */

			return ADD_TO_MLQUEUE;

		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)

		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {

			/*

			 * ALUA state changed

			 */

			alua_check(sdev, true);

			return ADD_TO_MLQUEUE;

		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07)

		}

		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {

			/*

			 * Implicit ALUA state transition failed

			 */

			alua_check(sdev, true);

			return ADD_TO_MLQUEUE;

		}

		if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)

			/*

			 * Inquiry data has changed
@@ -708,7 +719,7 @@ static void alua_rtpg_work(struct work_struct *work) 
		spin_unlock_irqrestore(&pg->lock, flags);

		err = alua_rtpg(sdev, pg);

		spin_lock_irqsave(&pg->lock, flags);

		if (err == SCSI_DH_RETRY) {

		if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {

			pg->flags &= ~ALUA_PG_RUNNING;

			pg->flags |= ALUA_PG_RUN_RTPG;

			spin_unlock_irqrestore(&pg->lock, flags);
@@ -724,7 +735,7 @@ static void alua_rtpg_work(struct work_struct *work) 
		spin_unlock_irqrestore(&pg->lock, flags);

		err = alua_stpg(sdev, pg);

		spin_lock_irqsave(&pg->lock, flags);

		if (err == SCSI_DH_RETRY) {

		if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {

			pg->flags |= ALUA_PG_RUN_RTPG;

			pg->interval = 0;

			pg->flags &= ~ALUA_PG_RUNNING;
@@ -754,7 +765,7 @@ static void alua_rtpg_work(struct work_struct *work) 


static void alua_rtpg_queue(struct alua_port_group *pg,

			    struct scsi_device *sdev,

			    struct alua_queue_data *qdata)

			    struct alua_queue_data *qdata, bool force)

{

	int start_queue = 0;

	unsigned long flags;
@@ -767,6 +778,7 @@ static void alua_rtpg_queue(struct alua_port_group *pg, 
	if (qdata) {

		list_add_tail(&qdata->entry, &pg->rtpg_list);

		pg->flags |= ALUA_PG_RUN_STPG;

		force = true;

	}

	if (pg->rtpg_sdev == NULL) {

		pg->interval = 0;
@@ -775,7 +787,15 @@ static void alua_rtpg_queue(struct alua_port_group *pg, 
		pg->rtpg_sdev = sdev;

		scsi_device_get(sdev);

		start_queue = 1;

	} else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {

		pg->flags |= ALUA_PG_RUN_RTPG;

		/* Do not queue if the worker is already running */

		if (!(pg->flags & ALUA_PG_RUNNING)) {

			kref_get(&pg->kref);

			start_queue = 1;

		}

	}



	if (pg->flags & ALUA_SYNC_STPG)

		alua_wq = kaluad_sync_wq;

	spin_unlock_irqrestore(&pg->lock, flags);
@@ -890,7 +910,7 @@ static int alua_activate(struct scsi_device *sdev, 
	rcu_read_unlock();

	mutex_unlock(&h->init_mutex);



	alua_rtpg_queue(pg, sdev, qdata);

	alua_rtpg_queue(pg, sdev, qdata, true);

	kref_put(&pg->kref, release_port_group);

out:

	if (fn)
@@ -898,6 +918,29 @@ out: 
	return 0;

}



/*

 * alua_check - check path status

 * @sdev: device on the path to be checked

 *

 * Check the device status

 */

static void alua_check(struct scsi_device *sdev, bool force)

{

	struct alua_dh_data *h = sdev->handler_data;

	struct alua_port_group *pg;



	rcu_read_lock();

	pg = rcu_dereference(h->pg);

	if (!pg || !kref_get_unless_zero(&pg->kref)) {

		rcu_read_unlock();

		return;

	}

	rcu_read_unlock();



	alua_rtpg_queue(pg, sdev, NULL, force);

	kref_put(&pg->kref, release_port_group);

}



/*

 * alua_prep_fn - request callback

 *

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