scsi_dh_alua: update 'access_state' field

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

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Ewan Milne <emilne@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files 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 19f653930f7c..5bcdf8dd6fb0 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <asm/unaligned.h>
 #include <scsi/scsi.h>
+#include <scsi/scsi_proto.h>
 #include <scsi/scsi_dbg.h>
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_dh.h>
@@ -75,6 +76,7 @@ struct alua_port_group {
         struct kref             kref;
         struct rcu_head         rcu;
         struct list_head        node;
+        struct list_head        dh_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_head        node;
         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(&pg->rtpg_work, alua_rtpg_work);
         INIT_LIST_HEAD(&pg->rtpg_list);
         INIT_LIST_HEAD(&pg->node);
+        INIT_LIST_HEAD(&pg->dh_list);
         spin_lock_init(&pg->lock);
 
         spin_lock(&port_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, &rel_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(&old_pg->lock, flags);
+                        list_del_rcu(&h->node);
+                        spin_unlock_irqrestore(&old_pg->lock, flags);
+                }
                 rcu_assign_pointer(h->pg, pg);
+                pg_updated = true;
         }
+
+        spin_lock_irqsave(&pg->lock, flags);
         if (sdev->synchronous_alua)
                 pg->flags |= ALUA_SYNC_STPG;
+        if (pg_updated)
+                list_add_rcu(&h->node, &pg->dh_list);
+        spin_unlock_irqrestore(&pg->lock, flags);
+
         alua_rtpg_queue(h->pg, sdev, NULL, true);
         spin_unlock(&h->pg_lock);
 
@@ -613,8 +631,18 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
                         if (spin_trylock_irqsave(&tmp_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,
+                                                &tmp_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, &pg->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();
                 }
                 break;
         case SCSI_ACCESS_STATE_OFFLINE:
@@ -1041,6 +1081,7 @@ static int alua_bus_attach(struct scsi_device *sdev)
         rcu_assign_pointer(h->pg, NULL);
         h->init_error = SCSI_DH_OK;
         h->sdev = sdev;
+        INIT_LIST_HEAD(&h->node);
 
         mutex_init(&h->init_mutex);
         err = alua_initialize(sdev, h);
@@ -1070,9 +1111,12 @@ static void alua_bus_detach(struct scsi_device *sdev)
         rcu_assign_pointer(h->pg, NULL);
         h->sdev = NULL;
         spin_unlock(&h->pg_lock);
-        if (pg)
+        if (pg) {
+                spin_lock(&pg->lock);
+                list_del_rcu(&h->node);
+                spin_unlock(&pg->lock);
                 kref_put(&pg->kref, release_port_group);
-
+        }
         sdev->handler_data = NULL;
         kfree(h);
 }