[PATCH 08/13] scsi: iscsi: fix lun/target reset cmd cleanup handling

[Mike Christie <michael.christie@oracle.com>]

If we are handling a sg io reset new cmds can be queued to the driver
while we are executing the reset. If the TMF completes ok, then when
we cleanup the running tasks the driver and libiscsi might disagree
on what commands were running, and one layer might cleanup cmds the
other didn't. This has us block our queuecommand while we process
the reset, so both layers know what cmds are running.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/scsi/libiscsi.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 04633e5157e9..c68afcca51a0 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -1922,12 +1922,11 @@ static void fail_scsi_tasks(struct iscsi_conn *conn, u64 lun, int error)
  * iscsi_suspend_queue - suspend iscsi_queuecommand
  * @conn: iscsi conn to stop queueing IO on
  *
- * This grabs the session frwd_lock to make sure no one is in
- * xmit_task/queuecommand, and then sets suspend to prevent
- * new commands from being queued. This only needs to be called
- * by offload drivers that need to sync a path like ep disconnect
- * with the iscsi_queuecommand/xmit_task. To start IO again libiscsi
- * will call iscsi_start_tx and iscsi_unblock_session when in FFP.
+ * This grabs the session frwd_lock to make sure no one is in queuecommand, and
+ * then sets suspend to prevent new commands from being queued. This only needs
+ * to be called by libiscsi or offload drivers that need to sync a path like
+ * ep disconnect with the iscsi_queuecommand. To start IO again libiscsi will
+ * call iscsi_start_tx and/or iscsi_unblock_session when in FFP.
  */
 void iscsi_suspend_queue(struct iscsi_conn *conn)
 {
@@ -2365,6 +2364,13 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
 	if (conn->tmf_state != TMF_INITIAL)
 		goto unlock;
 	conn->tmf_state = TMF_QUEUED;
+	/*
+	 * For sg based ioctls stop IO so we can sync up with the drivers
+	 * on what commands need to be cleaned up. If this function fails
+	 * we can leave suspended since the session will be droppped or
+	 * has already dropped.
+	 */
+	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
 
 	hdr = &conn->tmhdr;
 	iscsi_prep_lun_reset_pdu(sc, hdr);
@@ -2384,6 +2390,7 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
 		goto done;
 	default:
 		conn->tmf_state = TMF_INITIAL;
+		iscsi_start_tx(conn);
 		goto unlock;
 	}
 
@@ -2528,6 +2535,13 @@ static int iscsi_eh_target_reset(struct scsi_cmnd *sc)
 	if (conn->tmf_state != TMF_INITIAL)
 		goto unlock;
 	conn->tmf_state = TMF_QUEUED;
+	/*
+	 * For sg based ioctls stop IO so we can sync up with the drivers
+	 * on what commands need to be cleaned up. If this function fails
+	 * we can leave suspended since the session will be droppped or
+	 * has already dropped.
+	 */
+	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
 
 	hdr = &conn->tmhdr;
 	iscsi_prep_tgt_reset_pdu(sc, hdr);
@@ -2547,6 +2561,7 @@ static int iscsi_eh_target_reset(struct scsi_cmnd *sc)
 		goto done;
 	default:
 		conn->tmf_state = TMF_INITIAL;
+		iscsi_start_tx(conn);
 		goto unlock;
 	}
 
-- 
2.25.1