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: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 76 +++++++++++++++++++++++++-----
1 file changed, 64 insertions(+), 12 deletions(-)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 9d5a861..08c434a 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -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
@@ -710,7 +721,7 @@ 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);
@@ -726,7 +737,7 @@ 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;
@@ -756,7 +767,7 @@ 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;
@@ -769,6 +780,7 @@ 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;
@@ -777,7 +789,15 @@ 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);
@@ -892,7 +912,7 @@ 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)
@@ -901,6 +921,38 @@ out:
}
/*
+ * 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;
+
+ /*
+ * This is run asynchronously, and might race with
+ * alua_initialize() which provides the same functionality.
+ * So skip it if alua_initialize() is running.
+ */
+ if (!mutex_trylock(&h->init_mutex))
+ return;
+ rcu_read_lock();
+ pg = rcu_dereference(h->pg);
+ if (!pg || !kref_get_unless_zero(&pg->kref)) {
+ rcu_read_unlock();
+ mutex_unlock(&h->init_mutex);
+ return;
+ }
+ rcu_read_unlock();
+ mutex_unlock(&h->init_mutex);
+
+ alua_rtpg_queue(pg, sdev, NULL, force);
+ kref_put(&pg->kref, release_port_group);
+}
+
+/*
* alua_prep_fn - request callback
*
* Fail I/O to all paths not in state
--
1.8.5.6
--
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