Re: [PATCH 13/20] scsi_dh_alua: Recheck state on unit attention

2015-12-31 Thread Hannes Reinecke 

On 12/30/2015 02:22 PM, Christoph Hellwig wrote:

On Tue, Dec 08, 2015 at 08:37:33AM +0100, Hannes Reinecke wrote:

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.

Signed-off-by: Hannes Reinecke 
---
  drivers/scsi/device_handler/scsi_dh_alua.c | 58 --
  1 file changed, 47 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c 
b/drivers/scsi/device_handler/scsi_dh_alua.c
index 525449f..04a3a543 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -121,7 +121,8 @@ 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)
  {
@@ -386,7 +387,7 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h,
rcu_assign_pointer(h->pg, pg);
pg_found = true;
}
-   alua_rtpg_queue(h->pg, sdev, NULL);
+   alua_rtpg_queue(h->pg, sdev, NULL, true);
spin_unlock(>pg_lock);

if (pg_found)
@@ -427,18 +428,24 @@ 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
@@ -449,16 +456,20 @@ 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
@@ -777,7 +788,7 @@ 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;
@@ -797,7 +808,9 @@ 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)
+   start_queue = 1;
+
spin_unlock_irqrestore(>lock, flags);

if (start_queue &&
@@ -912,7 +925,7 @@ static int alua_activate(struct scsi_device *sdev,
kref_get(>kref);

Re: [PATCH 13/20] scsi_dh_alua: Recheck state on unit attention

2015-12-30 Thread Christoph Hellwig 
On Tue, Dec 08, 2015 at 08:37:33AM +0100, Hannes Reinecke wrote:
> 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.
> 
> Signed-off-by: Hannes Reinecke 
> ---
>  drivers/scsi/device_handler/scsi_dh_alua.c | 58 
> --
>  1 file changed, 47 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c 
> b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 525449f..04a3a543 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -121,7 +121,8 @@ 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)
>  {
> @@ -386,7 +387,7 @@ static int alua_check_vpd(struct scsi_device *sdev, 
> struct alua_dh_data *h,
>   rcu_assign_pointer(h->pg, pg);
>   pg_found = true;
>   }
> - alua_rtpg_queue(h->pg, sdev, NULL);
> + alua_rtpg_queue(h->pg, sdev, NULL, true);
>   spin_unlock(>pg_lock);
>  
>   if (pg_found)
> @@ -427,18 +428,24 @@ 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
> @@ -449,16 +456,20 @@ 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
> @@ -777,7 +788,7 @@ 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;
> @@ -797,7 +808,9 @@ 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)
> + start_queue = 1;
> +
>   spin_unlock_irqrestore(>lock, flags);
>  
>   if (start_queue &&
> @@ -912,7 +925,7 @@ static int alua_activate(struct scsi_device *sdev,
>

[PATCH 13/20] scsi_dh_alua: Recheck state on unit attention

2015-12-07 Thread Hannes Reinecke 
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.

Signed-off-by: Hannes Reinecke 
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 58 --
 1 file changed, 47 insertions(+), 11 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c 
b/drivers/scsi/device_handler/scsi_dh_alua.c
index 525449f..04a3a543 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -121,7 +121,8 @@ 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)
 {
@@ -386,7 +387,7 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h,
rcu_assign_pointer(h->pg, pg);
pg_found = true;
}
-   alua_rtpg_queue(h->pg, sdev, NULL);
+   alua_rtpg_queue(h->pg, sdev, NULL, true);
spin_unlock(>pg_lock);
 
if (pg_found)
@@ -427,18 +428,24 @@ 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
@@ -449,16 +456,20 @@ 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
@@ -777,7 +788,7 @@ 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;
@@ -797,7 +808,9 @@ 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)
+   start_queue = 1;
+
spin_unlock_irqrestore(>lock, flags);
 
if (start_queue &&
@@ -912,7 +925,7 @@ static int alua_activate(struct scsi_device *sdev,
kref_get(>kref);
rcu_read_unlock();
 
-   alua_rtpg_queue(pg, sdev, qdata);
+   alua_rtpg_queue(pg, sdev, qdata, true);