iscsi/iser-target: Support multi-sequence sendtargets text response

In case sendtargets response is larger than initiator MRDSL, we
send a partial sendtargets response (setting F=0, C=1, TTT!=0xffffffff),
accept a consecutive empty text message and send the rest of the payload.
In case we are done, we set F=1, C=0, TTT=0xffffffff.
We do that by storing the sendtargets response bytes done under
the session.

This patch also makes iscsit_find_cmd_from_itt public for isert.

(Re-add cmd->maxcmdsn_inc and clear in iscsit_build_text_rsp - nab)

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

3 files changed, 66 insertions, 23 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 75c29b687f35..f533a0dfa4de 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1994,6 +1994,7 @@ iscsit_setup_text_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	cmd->cmd_sn		= be32_to_cpu(hdr->cmdsn);
 	cmd->exp_stat_sn	= be32_to_cpu(hdr->exp_statsn);
 	cmd->data_direction	= DMA_NONE;
+	cmd->text_in_ptr	= NULL;
 
 	return 0;
 }
@@ -2007,9 +2008,13 @@ iscsit_process_text_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	int cmdsn_ret;
 
 	if (!text_in) {
-		pr_err("Unable to locate text_in buffer for sendtargets"
-		       " discovery\n");
-		goto reject;
+		cmd->targ_xfer_tag = be32_to_cpu(hdr->ttt);
+		if (cmd->targ_xfer_tag == 0xFFFFFFFF) {
+			pr_err("Unable to locate text_in buffer for sendtargets"
+			       " discovery\n");
+			goto reject;
+		}
+		goto empty_sendtargets;
 	}
 	if (strncmp("SendTargets", text_in, 11) != 0) {
 		pr_err("Received Text Data that is not"
@@ -2036,6 +2041,7 @@ iscsit_process_text_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 	list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
 	spin_unlock_bh(&conn->cmd_lock);
 
+empty_sendtargets:
 	iscsit_ack_from_expstatsn(conn, be32_to_cpu(hdr->exp_statsn));
 
 	if (!(hdr->opcode & ISCSI_OP_IMMEDIATE)) {
@@ -3385,7 +3391,8 @@ static bool iscsit_check_inaddr_any(struct iscsi_np *np)
 
 static int
 iscsit_build_sendtargets_response(struct iscsi_cmd *cmd,
-				  enum iscsit_transport_type network_transport)
+				  enum iscsit_transport_type network_transport,
+				  int skip_bytes, bool *completed)
 {
 	char *payload = NULL;
 	struct iscsi_conn *conn = cmd->conn;
@@ -3476,9 +3483,16 @@ iscsit_build_sendtargets_response(struct iscsi_cmd *cmd,
 						end_of_buf = 1;
 						goto eob;
 					}
-					memcpy(payload + payload_len, buf, len);
-					payload_len += len;
-					target_name_printed = 1;
+
+					if (skip_bytes && len <= skip_bytes) {
+						skip_bytes -= len;
+					} else {
+						memcpy(payload + payload_len, buf, len);
+						payload_len += len;
+						target_name_printed = 1;
+						if (len > skip_bytes)
+							skip_bytes = 0;
+					}
 				}
 
 				len = sprintf(buf, "TargetAddress="
@@ -3494,15 +3508,24 @@ iscsit_build_sendtargets_response(struct iscsi_cmd *cmd,
 					end_of_buf = 1;
 					goto eob;
 				}
-				memcpy(payload + payload_len, buf, len);
-				payload_len += len;
+
+				if (skip_bytes && len <= skip_bytes) {
+					skip_bytes -= len;
+				} else {
+					memcpy(payload + payload_len, buf, len);
+					payload_len += len;
+					if (len > skip_bytes)
+						skip_bytes = 0;
+				}
 			}
 			spin_unlock(&tpg->tpg_np_lock);
 		}
 		spin_unlock(&tiqn->tiqn_tpg_lock);
 eob:
-		if (end_of_buf)
+		if (end_of_buf) {
+			*completed = false;
 			break;
+		}
 
 		if (cmd->cmd_flags & IFC_SENDTARGETS_SINGLE)
 			break;
@@ -3520,13 +3543,23 @@ iscsit_build_text_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 		      enum iscsit_transport_type network_transport)
 {
 	int text_length, padding;
+	bool completed = true;
 
-	text_length = iscsit_build_sendtargets_response(cmd, network_transport);
+	text_length = iscsit_build_sendtargets_response(cmd, network_transport,
+							cmd->read_data_done,
+							&completed);
 	if (text_length < 0)
 		return text_length;
 
+	if (completed) {
+		hdr->flags |= ISCSI_FLAG_CMD_FINAL;
+	} else {
+		hdr->flags |= ISCSI_FLAG_TEXT_CONTINUE;
+		cmd->read_data_done += text_length;
+		if (cmd->targ_xfer_tag == 0xFFFFFFFF)
+			cmd->targ_xfer_tag = session_get_next_ttt(conn->sess);
+	}
 	hdr->opcode = ISCSI_OP_TEXT_RSP;
-	hdr->flags |= ISCSI_FLAG_CMD_FINAL;
 	padding = ((-text_length) & 3);
 	hton24(hdr->dlength, text_length);
 	hdr->itt = cmd->init_task_tag;
@@ -3535,21 +3568,25 @@ iscsit_build_text_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn,
 	hdr->statsn = cpu_to_be32(cmd->stat_sn);
 
 	iscsit_increment_maxcmdsn(cmd, conn->sess);
+	/*
+	 * Reset maxcmdsn_inc in multi-part text payload exchanges to
+	 * correctly increment MaxCmdSN for each response answering a
+	 * non immediate text request with a valid CmdSN.
+	 */
+	cmd->maxcmdsn_inc = 0;
 	hdr->exp_cmdsn = cpu_to_be32(conn->sess->exp_cmd_sn);
 	hdr->max_cmdsn = cpu_to_be32(conn->sess->max_cmd_sn);
 
-	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);
+	pr_debug("Built Text Response: ITT: 0x%08x, TTT: 0x%08x, StatSN: 0x%08x,"
+		" Length: %u, CID: %hu F: %d C: %d\n", cmd->init_task_tag,
+		cmd->targ_xfer_tag, cmd->stat_sn, text_length, conn->cid,
+		!!(hdr->flags & ISCSI_FLAG_CMD_FINAL),
+		!!(hdr->flags & ISCSI_FLAG_TEXT_CONTINUE));
 
 	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)
@@ -4013,9 +4050,15 @@ static int iscsi_target_rx_opcode(struct iscsi_conn *conn, unsigned char *buf)
 		ret = iscsit_handle_task_mgt_cmd(conn, cmd, buf);
 		break;
 	case ISCSI_OP_TEXT:
-		cmd = iscsit_allocate_cmd(conn, TASK_INTERRUPTIBLE);
-		if (!cmd)
-			goto reject;
+		if (hdr->ttt != cpu_to_be32(0xFFFFFFFF)) {
+			cmd = iscsit_find_cmd_from_itt(conn, hdr->itt);
+			if (!cmd)
+				goto reject;
+		} else {
+			cmd = iscsit_allocate_cmd(conn, TASK_INTERRUPTIBLE);
+			if (!cmd)
+				goto reject;
+		}
 
 		ret = iscsit_handle_text_cmd(conn, cmd, buf);
 		break;
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index c211d3f2726c..390df8ed72b2 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -390,6 +390,7 @@ struct iscsi_cmd *iscsit_find_cmd_from_itt(
 			init_task_tag, conn->cid);
 	return NULL;
 }
+EXPORT_SYMBOL(iscsit_find_cmd_from_itt);
 
 struct iscsi_cmd *iscsit_find_cmd_from_itt_or_dump(
 	struct iscsi_conn *conn,
diff --git a/drivers/target/iscsi/iscsi_target_util.h b/drivers/target/iscsi/iscsi_target_util.h
index a68508c4fec8..1ab754a671ff 100644
--- a/drivers/target/iscsi/iscsi_target_util.h
+++ b/drivers/target/iscsi/iscsi_target_util.h
@@ -16,7 +16,6 @@ extern struct iscsi_r2t *iscsit_get_holder_for_r2tsn(struct iscsi_cmd *, u32);
 extern int iscsit_sequence_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
 			       unsigned char * ,__be32 cmdsn);
 extern int iscsit_check_unsolicited_dataout(struct iscsi_cmd *, unsigned char *);
-extern struct iscsi_cmd *iscsit_find_cmd_from_itt(struct iscsi_conn *, itt_t);
 extern struct iscsi_cmd *iscsit_find_cmd_from_itt_or_dump(struct iscsi_conn *,
 			itt_t, u32);
 extern struct iscsi_cmd *iscsit_find_cmd_from_ttt(struct iscsi_conn *, u32);