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scsi_dh_alua: Recheck state on unit attention

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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>
This commit is contained in:
Hannes Reinecke 2016-02-19 09:17:13 +01:00 committed by Martin K. Petersen
parent 851cde9909
commit 2b35865e7a
1 changed files with 55 additions and 12 deletions
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67
drivers/scsi/device_handler/scsi_dh_alua.c
View file

@ -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 @@ static int alua_activate(struct scsi_device *sdev,
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
*