scsi: qedi: Fix cleanup session block/unblock use

Drivers shouldn't be calling block/unblock session for cmd cleanup because
the functions can change the session state from under libiscsi.  This adds
a new a driver level bit so it can block all I/O the host while it drains
the card.

Link: https://lore.kernel.org/r/20210525181821.7617-26-michael.christie@oracle.com
Reviewed-by: Manish Rangankar <mrangankar@marvell.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qedi/qedi.h

@@ -284,6 +284,7 @@ struct qedi_ctx {
 #define QEDI_IN_RECOVERY	5
 #define QEDI_IN_OFFLINE		6
 #define QEDI_IN_SHUTDOWN	7
+#define QEDI_BLOCK_IO		8
 
 	u8 mac[ETH_ALEN];
 	u32 src_ip[4];

drivers/scsi/qedi/qedi_iscsi.c

@@ -330,12 +330,22 @@ free_conn:
 
 void qedi_mark_device_missing(struct iscsi_cls_session *cls_session)
 {
-	iscsi_block_session(cls_session);
+	struct iscsi_session *session = cls_session->dd_data;
+	struct qedi_conn *qedi_conn = session->leadconn->dd_data;
+
+	spin_lock_bh(&session->frwd_lock);
+	set_bit(QEDI_BLOCK_IO, &qedi_conn->qedi->flags);
+	spin_unlock_bh(&session->frwd_lock);
 }
 
 void qedi_mark_device_available(struct iscsi_cls_session *cls_session)
 {
-	iscsi_unblock_session(cls_session);
+	struct iscsi_session *session = cls_session->dd_data;
+	struct qedi_conn *qedi_conn = session->leadconn->dd_data;
+
+	spin_lock_bh(&session->frwd_lock);
+	clear_bit(QEDI_BLOCK_IO, &qedi_conn->qedi->flags);
+	spin_unlock_bh(&session->frwd_lock);
 }
 
 static int qedi_bind_conn_to_iscsi_cid(struct qedi_ctx *qedi,
@@ -800,6 +810,9 @@ static int qedi_task_xmit(struct iscsi_task *task)
 	if (test_bit(QEDI_IN_SHUTDOWN, &qedi_conn->qedi->flags))
 		return -ENODEV;
 
+	if (test_bit(QEDI_BLOCK_IO, &qedi_conn->qedi->flags))
+		return -EACCES;
+
 	cmd->state = 0;
 	cmd->task = NULL;
 	cmd->use_slowpath = false;