iscsi-target: Refactor ISCSI_OP_TEXT_RSP TX handling

This patch refactoring existing iscsit_send_text_rsp() in order
to handle iscsi_text_rsp payloads in a transport specific manner.

This includes the addition of iscsit_build_text_rsp() to build
the response payload and initialize ISCSI_OP_TEXT_RSP.

v2: Make iscsit_build_text_rsp() determine extra padding bytes, and
    drop legacy padding calculation for traditional iSCSI text
    responses within iscsit_send_text_rsp()
Reported-by: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -3461,52 +3461,62 @@ static int iscsit_build_sendtargets_response(struct iscsi_cmd *cmd)
 	return payload_len;
 }
 
-/*
- *	FIXME: Add support for F_BIT and C_BIT when the length is longer than
- *	MaxRecvDataSegmentLength.
- */
-static int iscsit_send_text_rsp(
-	struct iscsi_cmd *cmd,
-	struct iscsi_conn *conn)
+int
+iscsit_build_text_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
+		      struct iscsi_text_rsp *hdr)
 {
-	struct iscsi_text_rsp *hdr;
-	struct kvec *iov;
-	u32 padding = 0, tx_size = 0;
-	int text_length, iov_count = 0;
+	int text_length, padding;
 
 	text_length = iscsit_build_sendtargets_response(cmd);
 	if (text_length < 0)
 		return text_length;
 
+	hdr->opcode = ISCSI_OP_TEXT_RSP;
+	hdr->flags |= ISCSI_FLAG_CMD_FINAL;
 	padding = ((-text_length) & 3);
-	if (padding != 0) {
-		memset(cmd->buf_ptr + text_length, 0, padding);
-		pr_debug("Attaching %u additional bytes for"
-			" padding.\n", padding);
-	}
-
-	hdr			= (struct iscsi_text_rsp *) cmd->pdu;
-	memset(hdr, 0, ISCSI_HDR_LEN);
-	hdr->opcode		= ISCSI_OP_TEXT_RSP;
-	hdr->flags		|= ISCSI_FLAG_CMD_FINAL;
 	hton24(hdr->dlength, text_length);
-	hdr->itt		= cmd->init_task_tag;
-	hdr->ttt		= cpu_to_be32(cmd->targ_xfer_tag);
-	cmd->stat_sn		= conn->stat_sn++;
-	hdr->statsn		= cpu_to_be32(cmd->stat_sn);
+	hdr->itt = cmd->init_task_tag;
+	hdr->ttt = cpu_to_be32(cmd->targ_xfer_tag);
+	cmd->stat_sn = conn->stat_sn++;
+	hdr->statsn = cpu_to_be32(cmd->stat_sn);
 
 	iscsit_increment_maxcmdsn(cmd, conn->sess);
-	hdr->exp_cmdsn		= cpu_to_be32(conn->sess->exp_cmd_sn);
-	hdr->max_cmdsn		= cpu_to_be32(conn->sess->max_cmd_sn);
+	hdr->exp_cmdsn = cpu_to_be32(conn->sess->exp_cmd_sn);
+	hdr->max_cmdsn = cpu_to_be32(conn->sess->max_cmd_sn);
 
-	iov = &cmd->iov_misc[0];
+	pr_debug("Built Text Response: ITT: 0x%08x, StatSN: 0x%08x,"
+		" Length: %u, CID: %hu\n", cmd->init_task_tag, cmd->stat_sn,
+		text_length, conn->cid);
+
+	return text_length + padding;
+}
+EXPORT_SYMBOL(iscsit_build_text_rsp);
 
+/*
+ *	FIXME: Add support for F_BIT and C_BIT when the length is longer than
+ *	MaxRecvDataSegmentLength.
+ */
+static int iscsit_send_text_rsp(
+	struct iscsi_cmd *cmd,
+	struct iscsi_conn *conn)
+{
+	struct iscsi_text_rsp *hdr = (struct iscsi_text_rsp *)cmd->pdu;
+	struct kvec *iov;
+	u32 tx_size = 0;
+	int text_length, iov_count = 0, rc;
+
+	rc = iscsit_build_text_rsp(cmd, conn, hdr);
+	if (rc < 0)
+		return rc;
+
+	text_length = rc;
+	iov = &cmd->iov_misc[0];
 	iov[iov_count].iov_base = cmd->pdu;
 	iov[iov_count++].iov_len = ISCSI_HDR_LEN;
 	iov[iov_count].iov_base	= cmd->buf_ptr;
-	iov[iov_count++].iov_len = text_length + padding;
+	iov[iov_count++].iov_len = text_length;
 
-	tx_size += (ISCSI_HDR_LEN + text_length + padding);
+	tx_size += (ISCSI_HDR_LEN + text_length);
 
 	if (conn->conn_ops->HeaderDigest) {
 		u32 *header_digest = (u32 *)&cmd->pdu[ISCSI_HDR_LEN];
@@ -3522,7 +3532,7 @@ static int iscsit_send_text_rsp(
 
 	if (conn->conn_ops->DataDigest) {
 		iscsit_do_crypto_hash_buf(&conn->conn_tx_hash,
-				cmd->buf_ptr, (text_length + padding),
+				cmd->buf_ptr, text_length,
 				0, NULL, (u8 *)&cmd->data_crc);
 
 		iov[iov_count].iov_base	= &cmd->data_crc;
@@ -3530,16 +3540,13 @@ static int iscsit_send_text_rsp(
 		tx_size	+= ISCSI_CRC_LEN;
 
 		pr_debug("Attaching DataDigest for %u bytes of text"
-			" data, CRC 0x%08x\n", (text_length + padding),
+			" data, CRC 0x%08x\n", text_length,
 			cmd->data_crc);
 	}
 
 	cmd->iov_misc_count = iov_count;
 	cmd->tx_size = tx_size;
 
-	pr_debug("Built Text Response: ITT: 0x%08x, StatSN: 0x%08x,"
-		" Length: %u, CID: %hu\n", cmd->init_task_tag, cmd->stat_sn,
-			text_length, conn->cid);
 	return 0;
 }
 

include/target/iscsi/iscsi_transport.h

@@ -63,6 +63,8 @@ extern void iscsit_build_nopin_rsp(struct iscsi_cmd *, struct iscsi_conn *,
 				struct iscsi_nopin *, bool);
 extern void iscsit_build_task_mgt_rsp(struct iscsi_cmd *, struct iscsi_conn *,
 				struct iscsi_tm_rsp *);
+extern int iscsit_build_text_rsp(struct iscsi_cmd *, struct iscsi_conn *,
+				struct iscsi_text_rsp *);
 extern void iscsit_build_reject(struct iscsi_cmd *, struct iscsi_conn *,
 				struct iscsi_reject *);
 extern int iscsit_build_logout_rsp(struct iscsi_cmd *, struct iscsi_conn *,