[SCSI] libata, libsas: introduce sched_eh and end_eh port ops

When managing shost->host_eh_scheduled libata assumes that there is a
1:1 shost-to-ata_port relationship.  libsas creates a 1:N relationship
so it needs to manage host_eh_scheduled cumulatively at the host level.
The sched_eh and end_eh port port ops allow libsas to track when domain
devices enter/leave the "eh-pending" state under ha->lock (previously
named ha->state_lock, but it is no longer just a lock for ha->state
changes).

Since host_eh_scheduled indicates eh without backing commands pinning
the device it can be deallocated at any time.  Move the taking of the
domain_device reference under the port_lock to guarantee that the
ata_port stays around for the duration of eh.

Reviewed-by: Jacek Danecki <jacek.danecki@intel.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 10cb5ae..6909fef 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -114,7 +114,7 @@
 		sas_ha->lldd_queue_size = 128; /* Sanity */
 
 	set_bit(SAS_HA_REGISTERED, &sas_ha->state);
-	spin_lock_init(&sas_ha->state_lock);
+	spin_lock_init(&sas_ha->lock);
 	mutex_init(&sas_ha->drain_mutex);
 	INIT_LIST_HEAD(&sas_ha->defer_q);
 
@@ -163,9 +163,9 @@
 	 * events to be queued, and flush any in-progress drainers
 	 */
 	mutex_lock(&sas_ha->drain_mutex);
-	spin_lock_irq(&sas_ha->state_lock);
+	spin_lock_irq(&sas_ha->lock);
 	clear_bit(SAS_HA_REGISTERED, &sas_ha->state);
-	spin_unlock_irq(&sas_ha->state_lock);
+	spin_unlock_irq(&sas_ha->lock);
 	__sas_drain_work(sas_ha);
 	mutex_unlock(&sas_ha->drain_mutex);
 
@@ -411,9 +411,9 @@
 	d->reset_result = 0;
 	d->hard_reset = hard_reset;
 
-	spin_lock_irq(&ha->state_lock);
+	spin_lock_irq(&ha->lock);
 	sas_queue_work(ha, &d->reset_work);
-	spin_unlock_irq(&ha->state_lock);
+	spin_unlock_irq(&ha->lock);
 
 	rc = sas_drain_work(ha);
 	if (rc == 0)
@@ -438,9 +438,9 @@
 	d->enable_result = 0;
 	d->enable = enable;
 
-	spin_lock_irq(&ha->state_lock);
+	spin_lock_irq(&ha->lock);
 	sas_queue_work(ha, &d->enable_work);
-	spin_unlock_irq(&ha->state_lock);
+	spin_unlock_irq(&ha->lock);
 
 	rc = sas_drain_work(ha);
 	if (rc == 0)