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>

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 19f6539..5bcdf8d 100644 (file)
--- 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);
 }