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: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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@ -120,7 +120,8 @@ struct alua_queue_data {
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static void alua_rtpg_work(struct work_struct *work);
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static void alua_rtpg_queue(struct alua_port_group *pg,
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struct scsi_device *sdev,
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struct alua_queue_data *qdata);
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struct alua_queue_data *qdata, bool force);
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static void alua_check(struct scsi_device *sdev, bool force);
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static void release_port_group(struct kref *kref)
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{
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@ -368,7 +369,7 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
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}
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if (sdev->synchronous_alua)
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pg->flags |= ALUA_SYNC_STPG;
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alua_rtpg_queue(h->pg, sdev, NULL);
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alua_rtpg_queue(h->pg, sdev, NULL, true);
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spin_unlock(&h->pg_lock);
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if (old_pg)
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@ -404,18 +405,24 @@ static int alua_check_sense(struct scsi_device *sdev,
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{
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switch (sense_hdr->sense_key) {
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case NOT_READY:
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if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a)
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if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
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/*
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* LUN Not Accessible - ALUA state transition
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*/
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return ADD_TO_MLQUEUE;
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alua_check(sdev, false);
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return NEEDS_RETRY;
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}
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break;
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case UNIT_ATTENTION:
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if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
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if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
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/*
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* Power On, Reset, or Bus Device Reset, just retry.
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* Power On, Reset, or Bus Device Reset.
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* Might have obscured a state transition,
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* so schedule a recheck.
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*/
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alua_check(sdev, true);
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return ADD_TO_MLQUEUE;
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}
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if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
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/*
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* Device internal reset
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@ -426,16 +433,20 @@ static int alua_check_sense(struct scsi_device *sdev,
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* Mode Parameters Changed
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*/
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return ADD_TO_MLQUEUE;
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if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)
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if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
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/*
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* ALUA state changed
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*/
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alua_check(sdev, true);
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return ADD_TO_MLQUEUE;
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if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07)
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}
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if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
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/*
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* Implicit ALUA state transition failed
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*/
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alua_check(sdev, true);
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return ADD_TO_MLQUEUE;
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}
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if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
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/*
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* Inquiry data has changed
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@ -708,7 +719,7 @@ static void alua_rtpg_work(struct work_struct *work)
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spin_unlock_irqrestore(&pg->lock, flags);
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err = alua_rtpg(sdev, pg);
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spin_lock_irqsave(&pg->lock, flags);
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if (err == SCSI_DH_RETRY) {
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if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
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pg->flags &= ~ALUA_PG_RUNNING;
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pg->flags |= ALUA_PG_RUN_RTPG;
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spin_unlock_irqrestore(&pg->lock, flags);
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@ -724,7 +735,7 @@ static void alua_rtpg_work(struct work_struct *work)
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spin_unlock_irqrestore(&pg->lock, flags);
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err = alua_stpg(sdev, pg);
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spin_lock_irqsave(&pg->lock, flags);
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if (err == SCSI_DH_RETRY) {
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if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
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pg->flags |= ALUA_PG_RUN_RTPG;
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pg->interval = 0;
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pg->flags &= ~ALUA_PG_RUNNING;
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@ -754,7 +765,7 @@ static void alua_rtpg_work(struct work_struct *work)
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static void alua_rtpg_queue(struct alua_port_group *pg,
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struct scsi_device *sdev,
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struct alua_queue_data *qdata)
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struct alua_queue_data *qdata, bool force)
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{
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int start_queue = 0;
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unsigned long flags;
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@ -767,6 +778,7 @@ static void alua_rtpg_queue(struct alua_port_group *pg,
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if (qdata) {
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list_add_tail(&qdata->entry, &pg->rtpg_list);
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pg->flags |= ALUA_PG_RUN_STPG;
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force = true;
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}
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if (pg->rtpg_sdev == NULL) {
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pg->interval = 0;
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@ -775,7 +787,15 @@ static void alua_rtpg_queue(struct alua_port_group *pg,
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pg->rtpg_sdev = sdev;
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scsi_device_get(sdev);
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start_queue = 1;
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} else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
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pg->flags |= ALUA_PG_RUN_RTPG;
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/* Do not queue if the worker is already running */
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if (!(pg->flags & ALUA_PG_RUNNING)) {
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kref_get(&pg->kref);
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start_queue = 1;
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}
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}
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if (pg->flags & ALUA_SYNC_STPG)
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alua_wq = kaluad_sync_wq;
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spin_unlock_irqrestore(&pg->lock, flags);
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@ -890,7 +910,7 @@ static int alua_activate(struct scsi_device *sdev,
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rcu_read_unlock();
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mutex_unlock(&h->init_mutex);
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alua_rtpg_queue(pg, sdev, qdata);
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alua_rtpg_queue(pg, sdev, qdata, true);
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kref_put(&pg->kref, release_port_group);
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out:
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if (fn)
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@ -898,6 +918,29 @@ out:
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return 0;
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}
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/*
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* alua_check - check path status
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* @sdev: device on the path to be checked
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*
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* Check the device status
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*/
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static void alua_check(struct scsi_device *sdev, bool force)
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{
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struct alua_dh_data *h = sdev->handler_data;
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struct alua_port_group *pg;
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rcu_read_lock();
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pg = rcu_dereference(h->pg);
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if (!pg || !kref_get_unless_zero(&pg->kref)) {
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rcu_read_unlock();
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return;
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}
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rcu_read_unlock();
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alua_rtpg_queue(pg, sdev, NULL, force);
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kref_put(&pg->kref, release_port_group);
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}
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/*
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* alua_prep_fn - request callback
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*
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