[SCSI] iscsi class: add session scanning

This just adds iscsi session scanning which works like fc rport scanning.
The future patches will hook the drivers into Mathew Wilcox's async
scanning infrastructure, so userspace does not have to special case
iscsi and so userspace does not have to make a extra special case for
hardware iscsi root scanning.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 30 insertions, 7 deletions

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index f876b0ae521a..af88955d0ec1 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -128,11 +128,11 @@ static int iscsi_setup_host(struct transport_container *tc, struct device *dev,
 	INIT_LIST_HEAD(&ihost->sessions);
 	mutex_init(&ihost->mutex);
 
-	snprintf(ihost->unbind_workq_name, KOBJ_NAME_LEN, "iscsi_unbind_%d",
+	snprintf(ihost->scan_workq_name, KOBJ_NAME_LEN, "iscsi_scan_%d",
 		shost->host_no);
-	ihost->unbind_workq = create_singlethread_workqueue(
-						ihost->unbind_workq_name);
-	if (!ihost->unbind_workq)
+	ihost->scan_workq = create_singlethread_workqueue(
+						ihost->scan_workq_name);
+	if (!ihost->scan_workq)
 		return -ENOMEM;
 	return 0;
 }
@@ -143,7 +143,7 @@ static int iscsi_remove_host(struct transport_container *tc, struct device *dev,
 	struct Scsi_Host *shost = dev_to_shost(dev);
 	struct iscsi_host *ihost = shost->shost_data;
 
-	destroy_workqueue(ihost->unbind_workq);
+	destroy_workqueue(ihost->scan_workq);
 	return 0;
 }
 
@@ -302,6 +302,23 @@ static int iscsi_user_scan(struct Scsi_Host *shost, uint channel,
 	return 0;
 }
 
+static void iscsi_scan_session(struct work_struct *work)
+{
+	struct iscsi_cls_session *session =
+			container_of(work, struct iscsi_cls_session, scan_work);
+	unsigned long flags;
+
+	spin_lock_irqsave(&session->lock, flags);
+	if (session->state != ISCSI_SESSION_LOGGED_IN) {
+		spin_unlock_irqrestore(&session->lock, flags);
+		return;
+	}
+	spin_unlock_irqrestore(&session->lock, flags);
+
+	scsi_scan_target(&session->dev, 0, session->target_id,
+			 SCAN_WILD_CARD, 1);
+}
+
 static void session_recovery_timedout(struct work_struct *work)
 {
 	struct iscsi_cls_session *session =
@@ -340,6 +357,8 @@ void __iscsi_unblock_session(struct iscsi_cls_session *session)
 
 void iscsi_unblock_session(struct iscsi_cls_session *session)
 {
+	struct Scsi_Host *shost = iscsi_session_to_shost(session);
+	struct iscsi_host *ihost = shost->shost_data;
 	unsigned long flags;
 
 	spin_lock_irqsave(&session->lock, flags);
@@ -347,6 +366,7 @@ void iscsi_unblock_session(struct iscsi_cls_session *session)
 	spin_unlock_irqrestore(&session->lock, flags);
 
 	__iscsi_unblock_session(session);
+	queue_work(ihost->scan_workq, &session->scan_work);
 }
 EXPORT_SYMBOL_GPL(iscsi_unblock_session);
 
@@ -390,7 +410,7 @@ static int iscsi_unbind_session(struct iscsi_cls_session *session)
 	struct Scsi_Host *shost = iscsi_session_to_shost(session);
 	struct iscsi_host *ihost = shost->shost_data;
 
-	return queue_work(ihost->unbind_workq, &session->unbind_work);
+	return queue_work(ihost->scan_workq, &session->unbind_work);
 }
 
 struct iscsi_cls_session *
@@ -411,6 +431,7 @@ iscsi_alloc_session(struct Scsi_Host *shost,
 	INIT_LIST_HEAD(&session->host_list);
 	INIT_LIST_HEAD(&session->sess_list);
 	INIT_WORK(&session->unbind_work, __iscsi_unbind_session);
+	INIT_WORK(&session->scan_work, iscsi_scan_session);
 	spin_lock_init(&session->lock);
 
 	/* this is released in the dev's release function */
@@ -530,13 +551,15 @@ void iscsi_remove_session(struct iscsi_cls_session *session)
 	spin_unlock_irqrestore(&session->lock, flags);
 	__iscsi_unblock_session(session);
 	iscsi_unbind_session(session);
+
+	/* flush running scans */
+	flush_workqueue(ihost->scan_workq);
 	/*
 	 * If the session dropped while removing devices then we need to make
 	 * sure it is not blocked
 	 */
 	if (!cancel_delayed_work(&session->recovery_work))
 		flush_workqueue(iscsi_eh_timer_workq);
-	flush_workqueue(ihost->unbind_workq);
 
 	/* hw iscsi may not have removed all connections from session */
 	err = device_for_each_child(&session->dev, NULL,