[PATCH 3/7] libiscsi: Check TMF state before sending PDU

[michaelc@cs.wisc.edu]

From: Mike Christie <michaelc@cs.wisc.edu>

Patch and mail from both MikeC and HannesR:

Before we're trying to send a PDU we have to check whether a TMF
is active. If so and if the PDU will be affected by the TMF
we should allow only Data-out PDUs to be sent.

If fast_abort is set, no Data-out PDUs will be sent while
a LUN reset is being processed for a affected LUN.

fast_abort is now ingored during a ABORT TASK tmf. We will not
send any Data-outs for a task if the task is being aborted.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/libiscsi.c    |  113 +++++++++++++++++++++++++++++++++++++++-----
 include/scsi/iscsi_proto.h |    2 +
 2 files changed, 103 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 8c29480..b6ffdc5 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -266,6 +266,88 @@ static int iscsi_prep_bidi_ahs(struct iscsi_task *task)
 }
 
 /**
+ * iscsi_check_tmf_restrictions - check if a task is affected by TMF
+ * @task: iscsi task
+ * @opcode: opcode to check for
+ *
+ * During TMF a task has to be checked if it's affected.
+ * All unrelated I/O can be passed through, but I/O to the
+ * affected LUN should be restricted.
+ * If 'fast_abort' is set we won't be sending any I/O to the
+ * affected LUN.
+ * Otherwise the target is waiting for all TTTs to be completed,
+ * so we have to send all outstanding Data-Out PDUs to the target.
+ */
+static int iscsi_check_tmf_restrictions(struct iscsi_task *task, int opcode)
+{
+	struct iscsi_conn *conn = task->conn;
+	struct iscsi_tm *tmf = &conn->tmhdr;
+	unsigned int hdr_lun;
+
+	if (conn->tmf_state == TMF_INITIAL)
+		return 0;
+
+	if ((tmf->opcode & ISCSI_OPCODE_MASK) != ISCSI_OP_SCSI_TMFUNC)
+		return 0;
+
+	switch (ISCSI_TM_FUNC_VALUE(tmf)) {
+	case ISCSI_TM_FUNC_LOGICAL_UNIT_RESET:
+		/*
+		 * Allow PDUs for unrelated LUNs
+		 */
+		hdr_lun = scsilun_to_int((struct scsi_lun *)tmf->lun);
+		if (hdr_lun != task->sc->device->lun)
+			return 0;
+
+		/*
+		 * Fail all SCSI cmd PDUs
+		 */
+		if (opcode != ISCSI_OP_SCSI_DATA_OUT) {
+			iscsi_conn_printk(KERN_INFO, conn,
+					  "task [op %x/%x itt "
+					  "0x%x/0x%x lun %u] "
+					  "rejected.\n",
+					  task->hdr->opcode, opcode,
+					  task->itt, task->hdr_itt, hdr_lun);
+			return -EACCES;
+		}
+		/*
+		 * And also all data-out PDUs in response to R2T
+		 * if fast_abort is set.
+		 */
+		if (conn->session->fast_abort) {
+			iscsi_conn_printk(KERN_INFO, conn,
+					  "task [op %x/%x itt "
+					  "0x%x/0x%x lun %u] "
+					  "fast abort.\n",
+					  task->hdr->opcode, opcode,
+					  task->itt, task->hdr_itt, hdr_lun);
+			return -EACCES;
+		}
+		break;
+	case ISCSI_TM_FUNC_ABORT_TASK:
+		/*
+		 * the caller has already checked if the task
+		 * they want to abort was in the pending queue so if
+		 * we are here the cmd pdu has gone out already, and
+		 * we will only hit this for data-outs
+		 */
+		if (opcode == ISCSI_OP_SCSI_DATA_OUT &&
+		    task->hdr_itt == tmf->rtt) {
+			ISCSI_DBG_SESSION(conn->session,
+					  "Preventing task %x/%x from sending "
+					  "data-out due to abort task in "
+					  "progress\n", task->itt,
+					  task->hdr_itt);
+			return -EACCES;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+/**
  * iscsi_prep_scsi_cmd_pdu - prep iscsi scsi cmd pdu
  * @task: iscsi task
  *
@@ -282,6 +364,10 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
 	itt_t itt;
 	int rc;
 
+	rc = iscsi_check_tmf_restrictions(task, ISCSI_OP_SCSI_CMD);
+	if (rc)
+		return rc;
+
 	if (conn->session->tt->alloc_pdu) {
 		rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_CMD);
 		if (rc)
@@ -1366,6 +1452,7 @@ EXPORT_SYMBOL_GPL(iscsi_requeue_task);
  **/
 static int iscsi_data_xmit(struct iscsi_conn *conn)
 {
+	struct iscsi_task *task;
 	int rc = 0;
 
 	spin_lock_bh(&conn->session->lock);
@@ -1403,11 +1490,8 @@ check_mgmt:
 
 	/* process pending command queue */
 	while (!list_empty(&conn->cmdqueue)) {
-		if (conn->tmf_state == TMF_QUEUED)
-			break;
-
-		conn->task = list_entry(conn->cmdqueue.next,
-					 struct iscsi_task, running);
+		conn->task = list_entry(conn->cmdqueue.next, struct iscsi_task,
+					running);
 		list_del_init(&conn->task->running);
 		if (conn->session->state == ISCSI_STATE_LOGGING_OUT) {
 			fail_scsi_task(conn->task, DID_IMM_RETRY);
@@ -1415,7 +1499,7 @@ check_mgmt:
 		}
 		rc = iscsi_prep_scsi_cmd_pdu(conn->task);
 		if (rc) {
-			if (rc == -ENOMEM) {
+			if (rc == -ENOMEM || rc == -EACCES) {
 				list_add_tail(&conn->task->running,
 					      &conn->cmdqueue);
 				conn->task = NULL;
@@ -1437,17 +1521,18 @@ check_mgmt:
 	}
 
 	while (!list_empty(&conn->requeue)) {
-		if (conn->session->fast_abort && conn->tmf_state != TMF_INITIAL)
-			break;
-
 		/*
 		 * we always do fastlogout - conn stop code will clean up.
 		 */
 		if (conn->session->state == ISCSI_STATE_LOGGING_OUT)
 			break;
 
-		conn->task = list_entry(conn->requeue.next,
-					 struct iscsi_task, running);
+		task = list_entry(conn->requeue.next, struct iscsi_task,
+				  running);
+		if (iscsi_check_tmf_restrictions(task, ISCSI_OP_SCSI_DATA_OUT))
+			break;
+
+		conn->task = task;
 		list_del_init(&conn->task->running);
 		conn->task->state = ISCSI_TASK_RUNNING;
 		rc = iscsi_xmit_task(conn);
@@ -1600,7 +1685,7 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 	if (!ihost->workq) {
 		reason = iscsi_prep_scsi_cmd_pdu(task);
 		if (reason) {
-			if (reason == -ENOMEM) {
+			if (reason == -ENOMEM ||  reason == -EACCES) {
 				reason = FAILURE_OOM;
 				goto prepd_reject;
 			} else {
@@ -2120,6 +2205,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 		spin_lock_bh(&session->lock);
 		fail_scsi_task(task, DID_ABORT);
 		conn->tmf_state = TMF_INITIAL;
+		memset(hdr, 0, sizeof(*hdr));
 		spin_unlock_bh(&session->lock);
 		iscsi_start_tx(conn);
 		goto success_unlocked;
@@ -2130,6 +2216,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 	case TMF_NOT_FOUND:
 		if (!sc->SCp.ptr) {
 			conn->tmf_state = TMF_INITIAL;
+			memset(hdr, 0, sizeof(*hdr));
 			/* task completed before tmf abort response */
 			ISCSI_DBG_EH(session, "sc completed while abort	in "
 					      "progress\n");
@@ -2224,6 +2311,7 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
 	iscsi_suspend_tx(conn);
 
 	spin_lock_bh(&session->lock);
+	memset(hdr, 0, sizeof(*hdr));
 	fail_scsi_tasks(conn, sc->device->lun, DID_ERROR);
 	conn->tmf_state = TMF_INITIAL;
 	spin_unlock_bh(&session->lock);
@@ -2868,6 +2956,7 @@ static void iscsi_start_session_recovery(struct iscsi_session *session,
 	spin_lock_bh(&session->lock);
 	fail_scsi_tasks(conn, -1, DID_TRANSPORT_DISRUPTED);
 	fail_mgmt_tasks(session, conn);
+	memset(&conn->tmhdr, 0, sizeof(conn->tmhdr));
 	spin_unlock_bh(&session->lock);
 	mutex_unlock(&session->eh_mutex);
 }
diff --git a/include/scsi/iscsi_proto.h b/include/scsi/iscsi_proto.h
index f2a2c11..dd0a52c 100644
--- a/include/scsi/iscsi_proto.h
+++ b/include/scsi/iscsi_proto.h
@@ -279,6 +279,8 @@ struct iscsi_tm {
 #define ISCSI_TM_FUNC_TARGET_COLD_RESET		7
 #define ISCSI_TM_FUNC_TASK_REASSIGN		8
 
+#define ISCSI_TM_FUNC_VALUE(hdr) ((hdr)->flags & ISCSI_FLAG_TM_FUNC_MASK)
+
 /* SCSI Task Management Response Header */
 struct iscsi_tm_rsp {
 	uint8_t opcode;
-- 
1.6.2.2