target/iscsi: split iscsit_check_dataout_hdr()

Split iscsit_check_dataout_hdr() into two functions
1. __iscsit_check_dataout_hdr() - This function
   validates data out hdr.
2. iscsit_check_dataout_hdr() - This function finds
   iSCSI cmd using iscsit_find_cmd_from_itt_or_dump(),
   then it calls __iscsit_check_dataout_hdr() to
   validate iSCSI hdr.

This split is required to support Chelsio T6 iSCSI
DDP completion feature. T6 adapters reduce number of
completions to host by generating single completion
for all directly placed(DDP) iSCSI pdus in a sequence,
DDP completion contains iSCSI hdr of the last pdu in a
sequence.

On receiving DDP completion cxgbit driver will first
find iSCSI cmd using iscsit_find_cmd_from_itt_or_dump()
then updates cmd->write_data_done, cmd->next_burst_len,
cmd->data_sn and calls  __iscsit_check_dataout_hdr()
to validate iSCSI hdr.

(Move XRDSL check ahead of itt lookup / dump - nab)

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -1431,36 +1431,17 @@ static void iscsit_do_crypto_hash_buf(
 }
 
 int
-iscsit_check_dataout_hdr(struct iscsi_conn *conn, unsigned char *buf,
-			  struct iscsi_cmd **out_cmd)
+__iscsit_check_dataout_hdr(struct iscsi_conn *conn, void *buf,
+			   struct iscsi_cmd *cmd, u32 payload_length,
+			   bool *success)
 {
-	struct iscsi_data *hdr = (struct iscsi_data *)buf;
-	struct iscsi_cmd *cmd = NULL;
+	struct iscsi_data *hdr = buf;
 	struct se_cmd *se_cmd;
-	u32 payload_length = ntoh24(hdr->dlength);
 	int rc;
 
-	if (!payload_length) {
-		pr_warn("DataOUT payload is ZERO, ignoring.\n");
-		return 0;
-	}
-
 	/* iSCSI write */
 	atomic_long_add(payload_length, &conn->sess->rx_data_octets);
 
-	if (payload_length > conn->conn_ops->MaxXmitDataSegmentLength) {
-		pr_err("DataSegmentLength: %u is greater than"
-			" MaxXmitDataSegmentLength: %u\n", payload_length,
-			conn->conn_ops->MaxXmitDataSegmentLength);
-		return iscsit_add_reject(conn, ISCSI_REASON_PROTOCOL_ERROR,
-					 buf);
-	}
-
-	cmd = iscsit_find_cmd_from_itt_or_dump(conn, hdr->itt,
-			payload_length);
-	if (!cmd)
-		return 0;
-
 	pr_debug("Got DataOut ITT: 0x%08x, TTT: 0x%08x,"
 		" DataSN: 0x%08x, Offset: %u, Length: %u, CID: %hu\n",
 		hdr->itt, hdr->ttt, hdr->datasn, ntohl(hdr->offset),
@@ -1553,10 +1534,44 @@ iscsit_check_dataout_hdr(struct iscsi_conn *conn, unsigned char *buf,
 		return 0;
 	else if (rc == DATAOUT_CANNOT_RECOVER)
 		return -1;
-
-	*out_cmd = cmd;
+	*success = true;
 	return 0;
 }
+EXPORT_SYMBOL(__iscsit_check_dataout_hdr);
+
+int
+iscsit_check_dataout_hdr(struct iscsi_conn *conn, void *buf,
+			 struct iscsi_cmd **out_cmd)
+{
+	struct iscsi_data *hdr = buf;
+	struct iscsi_cmd *cmd;
+	u32 payload_length = ntoh24(hdr->dlength);
+	int rc;
+	bool success = false;
+
+	if (!payload_length) {
+		pr_warn_ratelimited("DataOUT payload is ZERO, ignoring.\n");
+		return 0;
+	}
+
+	if (payload_length > conn->conn_ops->MaxXmitDataSegmentLength) {
+		pr_err_ratelimited("DataSegmentLength: %u is greater than"
+			" MaxXmitDataSegmentLength: %u\n", payload_length,
+			conn->conn_ops->MaxXmitDataSegmentLength);
+		return iscsit_add_reject(conn, ISCSI_REASON_PROTOCOL_ERROR, buf);
+	}
+
+	cmd = iscsit_find_cmd_from_itt_or_dump(conn, hdr->itt, payload_length);
+	if (!cmd)
+		return 0;
+
+	rc = __iscsit_check_dataout_hdr(conn, buf, cmd, payload_length, &success);
+
+	if (success)
+		*out_cmd = cmd;
+
+	return rc;
+}
 EXPORT_SYMBOL(iscsit_check_dataout_hdr);
 
 static int

drivers/target/iscsi/iscsi_target_util.c

@@ -417,6 +417,7 @@ struct iscsi_cmd *iscsit_find_cmd_from_itt_or_dump(
 
 	return NULL;
 }
+EXPORT_SYMBOL(iscsit_find_cmd_from_itt_or_dump);
 
 struct iscsi_cmd *iscsit_find_cmd_from_ttt(
 	struct iscsi_conn *conn,

include/target/iscsi/iscsi_transport.h

@@ -55,8 +55,12 @@ extern int iscsit_setup_scsi_cmd(struct iscsi_conn *, struct iscsi_cmd *,
 extern void iscsit_set_unsoliticed_dataout(struct iscsi_cmd *);
 extern int iscsit_process_scsi_cmd(struct iscsi_conn *, struct iscsi_cmd *,
 				struct iscsi_scsi_req *);
-extern int iscsit_check_dataout_hdr(struct iscsi_conn *, unsigned char *,
-				struct iscsi_cmd **);
+extern int
+__iscsit_check_dataout_hdr(struct iscsi_conn *, void *,
+			   struct iscsi_cmd *, u32, bool *);
+extern int
+iscsit_check_dataout_hdr(struct iscsi_conn *conn, void *buf,
+			 struct iscsi_cmd **out_cmd);
 extern int iscsit_check_dataout_payload(struct iscsi_cmd *, struct iscsi_data *,
 				bool);
 extern int iscsit_setup_nop_out(struct iscsi_conn *, struct iscsi_cmd *,
@@ -125,6 +129,9 @@ extern void iscsit_release_cmd(struct iscsi_cmd *);
 extern void iscsit_free_cmd(struct iscsi_cmd *, bool);
 extern void iscsit_add_cmd_to_immediate_queue(struct iscsi_cmd *,
 					      struct iscsi_conn *, u8);
+extern struct iscsi_cmd *
+iscsit_find_cmd_from_itt_or_dump(struct iscsi_conn *conn,
+				 itt_t init_task_tag, u32 length);
 
 /*
  * From iscsi_target_nego.c