Re: [PATCHv7 22/23] scsi_dh_alua: update 'access_state' field

[Bart Van Assche]

On 02/15/2016 12:24 AM, Hannes Reinecke wrote:

Track attached SCSI devices and update the 'access_state' field
whenever an ALUA state change has been detected.


Reviewed-by: Bart Van Assche 
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[PATCHv7 22/23] scsi_dh_alua: update 'access_state' field

[Hannes Reinecke]

Track attached SCSI devices and update the 'access_state' field
whenever an ALUA state change has been detected.

Reviewed-by: Ewan Milne 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Hannes Reinecke 
---
 drivers/scsi/device_handler/scsi_dh_alua.c | 48 --
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c 
b/drivers/scsi/device_handler/scsi_dh_alua.c
index cd636bc..3199aef 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -24,6 +24,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -75,6 +76,7 @@ struct alua_port_group {
struct kref kref;
struct rcu_head rcu;
struct list_headnode;
+   struct list_headdh_list;
unsigned char   device_id_str[256];
int device_id_len;
int group_id;
@@ -92,6 +94,7 @@ struct alua_port_group {
 };
 
 struct alua_dh_data {
+   struct list_headnode;
struct alua_port_group  *pg;
int group_id;
spinlock_t  pg_lock;
@@ -247,6 +250,7 @@ struct alua_port_group *alua_alloc_pg(struct scsi_device 
*sdev,
INIT_DELAYED_WORK(>rtpg_work, alua_rtpg_work);
INIT_LIST_HEAD(>rtpg_list);
INIT_LIST_HEAD(>node);
+   INIT_LIST_HEAD(>dh_list);
spin_lock_init(>lock);
 
spin_lock(_group_lock);
@@ -328,6 +332,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct 
alua_dh_data *h,
 {
int rel_port = -1, group_id;
struct alua_port_group *pg, *old_pg = NULL;
+   bool pg_updated;
+   unsigned long flags;
 
group_id = scsi_vpd_tpg_id(sdev, _port);
if (group_id < 0) {
@@ -357,10 +363,22 @@ static int alua_check_vpd(struct scsi_device *sdev, 
struct alua_dh_data *h,
old_pg = h->pg;
if (old_pg != pg) {
/* port group has changed. Update to new port group */
+   if (h->pg) {
+   spin_lock_irqsave(_pg->lock, flags);
+   list_del_rcu(>node);
+   spin_unlock_irqrestore(_pg->lock, flags);
+   }
rcu_assign_pointer(h->pg, pg);
+   pg_updated = true;
}
+
+   spin_lock_irqsave(>lock, flags);
if (sdev->synchronous_alua)
pg->flags |= ALUA_SYNC_STPG;
+   if (pg_updated)
+   list_add_rcu(>node, >dh_list);
+   spin_unlock_irqrestore(>lock, flags);
+
alua_rtpg_queue(h->pg, sdev, NULL, true);
spin_unlock(>pg_lock);
 
@@ -613,8 +631,18 @@ static int alua_rtpg(struct scsi_device *sdev, struct 
alua_port_group *pg)
if (spin_trylock_irqsave(_pg->lock, flags)) {
if ((tmp_pg == pg) ||
!(tmp_pg->flags & ALUA_PG_RUNNING)) {
+   struct alua_dh_data *h;
+
tmp_pg->state = desc[0] & 0x0f;
tmp_pg->pref = desc[0] >> 7;
+   rcu_read_lock();
+   list_for_each_entry_rcu(h,
+   _pg->dh_list, node) {
+   /* h->sdev should always be 
valid */
+   BUG_ON(!h->sdev);
+   h->sdev->access_state = desc[0];
+   }
+   rcu_read_unlock();
}
if (tmp_pg == pg)
valid_states = desc[1];
@@ -645,10 +673,22 @@ static int alua_rtpg(struct scsi_device *sdev, struct 
alua_port_group *pg)
pg->interval = 2;
err = SCSI_DH_RETRY;
} else {
+   struct alua_dh_data *h;
+
/* Transitioning time exceeded, set port to standby */
err = SCSI_DH_IO;
pg->state = SCSI_ACCESS_STATE_STANDBY;
pg->expiry = 0;
+   rcu_read_lock();
+   list_for_each_entry_rcu(h, >dh_list, node) {
+   BUG_ON(!h->sdev);
+   h->sdev->access_state =
+   (pg->state & SCSI_ACCESS_STATE_MASK);
+   if (pg->pref)
+   h->sdev->access_state |=
+   SCSI_ACCESS_STATE_PREFERRED;
+   }
+   rcu_read_unlock();
}