text: /*******************************************************************************
   * This file contains error recovery level one used by the iSCSI Target driver.
   *
   * (c) Copyright 2007-2013 Datera, Inc.
   *
   * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   ******************************************************************************/
  
  #include <linux/list.h>
  #include <scsi/iscsi_proto.h>
  #include <target/target_core_base.h>
  #include <target/target_core_fabric.h>
  #include <target/iscsi/iscsi_transport.h>
  
  #include "iscsi_target_core.h"
  #include "iscsi_target_seq_pdu_list.h"
  #include "iscsi_target_datain_values.h"
  #include "iscsi_target_device.h"
  #include "iscsi_target_tpg.h"
  #include "iscsi_target_util.h"
  #include "iscsi_target_erl0.h"
  #include "iscsi_target_erl1.h"
  #include "iscsi_target_erl2.h"
  #include "iscsi_target.h"
  
  #define OFFLOAD_BUF_SIZE	32768
  
  /*
   *	Used to dump excess datain payload for certain error recovery
   *	situations.  Receive in OFFLOAD_BUF_SIZE max of datain per rx_data().
   *
   *	dump_padding_digest denotes if padding and data digests need
   *	to be dumped.
   */
  int iscsit_dump_data_payload(
  	struct iscsi_conn *conn,
  	u32 buf_len,
  	int dump_padding_digest)
  {
  	char *buf, pad_bytes[4];
  	int ret = DATAOUT_WITHIN_COMMAND_RECOVERY, rx_got;
  	u32 length, padding, offset = 0, size;
  	struct kvec iov;
  
  	if (conn->sess->sess_ops->RDMAExtensions)
  		return 0;
  
  	length = (buf_len > OFFLOAD_BUF_SIZE) ? OFFLOAD_BUF_SIZE : buf_len;
  
  	buf = kzalloc(length, GFP_ATOMIC);
  	if (!buf) {
  		pr_err("Unable to allocate %u bytes for offload"
  				" buffer.\n", length);
  		return -1;
  	}
  	memset(&iov, 0, sizeof(struct kvec));
  
  	while (offset < buf_len) {
  		size = ((offset + length) > buf_len) ?
  			(buf_len - offset) : length;
  
  		iov.iov_len = size;
  		iov.iov_base = buf;
  
  		rx_got = rx_data(conn, &iov, 1, size);
  		if (rx_got != size) {
  			ret = DATAOUT_CANNOT_RECOVER;
  			goto out;
  		}
  
  		offset += size;
  	}
  
  	if (!dump_padding_digest)
  		goto out;
  
  	padding = ((-buf_len) & 3);
  	if (padding != 0) {
  		iov.iov_len = padding;
  		iov.iov_base = pad_bytes;
  
  		rx_got = rx_data(conn, &iov, 1, padding);
  		if (rx_got != padding) {
  			ret = DATAOUT_CANNOT_RECOVER;
  			goto out;
  		}
  	}
  
  	if (conn->conn_ops->DataDigest) {
  		u32 data_crc;
  
  		iov.iov_len = ISCSI_CRC_LEN;
  		iov.iov_base = &data_crc;
  
  		rx_got = rx_data(conn, &iov, 1, ISCSI_CRC_LEN);
  		if (rx_got != ISCSI_CRC_LEN) {
  			ret = DATAOUT_CANNOT_RECOVER;
  			goto out;
  		}
  	}
  
  out:
  	kfree(buf);
  	return ret;
  }
  
  /*
   *	Used for retransmitting R2Ts from a R2T SNACK request.
   */
  static int iscsit_send_recovery_r2t_for_snack(
  	struct iscsi_cmd *cmd,
  	struct iscsi_r2t *r2t)
  {
  	/*
  	 * If the struct iscsi_r2t has not been sent yet, we can safely
  	 * ignore retransmission
  	 * of the R2TSN in question.
  	 */
  	spin_lock_bh(&cmd->r2t_lock);
  	if (!r2t->sent_r2t) {
  		spin_unlock_bh(&cmd->r2t_lock);
  		return 0;
  	}
  	r2t->sent_r2t = 0;
  	spin_unlock_bh(&cmd->r2t_lock);
  
  	iscsit_add_cmd_to_immediate_queue(cmd, cmd->conn, ISTATE_SEND_R2T);
  
  	return 0;
  }
  
  static int iscsit_handle_r2t_snack(
  	struct iscsi_cmd *cmd,
  	unsigned char *buf,
  	u32 begrun,
  	u32 runlength)
  {
  	u32 last_r2tsn;
  	struct iscsi_r2t *r2t;
  
  	/*
  	 * Make sure the initiator is not requesting retransmission
  	 * of R2TSNs already acknowledged by a TMR TASK_REASSIGN.
  	 */
  	if ((cmd->cmd_flags & ICF_GOT_DATACK_SNACK) &&
  	    (begrun <= cmd->acked_data_sn)) {
  		pr_err("ITT: 0x%08x, R2T SNACK requesting"
  			" retransmission of R2TSN: 0x%08x to 0x%08x but already"
  			" acked to  R2TSN: 0x%08x by TMR TASK_REASSIGN,"
  			" protocol error.\n", cmd->init_task_tag, begrun,
  			(begrun + runlength), cmd->acked_data_sn);
  
  			return iscsit_reject_cmd(cmd,
  					ISCSI_REASON_PROTOCOL_ERROR, buf);
  	}
  
  	if (runlength) {
  		if ((begrun + runlength) > cmd->r2t_sn) {
  			pr_err("Command ITT: 0x%08x received R2T SNACK"
  			" with BegRun: 0x%08x, RunLength: 0x%08x, exceeds"
  			" current R2TSN: 0x%08x, protocol error.\n",
  			cmd->init_task_tag, begrun, runlength, cmd->r2t_sn);
  			return iscsit_reject_cmd(cmd,
  					ISCSI_REASON_BOOKMARK_INVALID, buf);
  		}
  		last_r2tsn = (begrun + runlength);
  	} else
  		last_r2tsn = cmd->r2t_sn;
  
  	while (begrun < last_r2tsn) {
  		r2t = iscsit_get_holder_for_r2tsn(cmd, begrun);
  		if (!r2t)
  			return -1;
  		if (iscsit_send_recovery_r2t_for_snack(cmd, r2t) < 0)
  			return -1;
  
  		begrun++;
  	}
  
  	return 0;
  }
  
  /*
   *	Generates Offsets and NextBurstLength based on Begrun and Runlength
   *	carried in a Data SNACK or ExpDataSN in TMR TASK_REASSIGN.
   *
   *	For DataSequenceInOrder=Yes and DataPDUInOrder=[Yes,No] only.
   *
   *	FIXME: How is this handled for a RData SNACK?
   */
  int iscsit_create_recovery_datain_values_datasequenceinorder_yes(
  	struct iscsi_cmd *cmd,
  	struct iscsi_datain_req *dr)
  {
  	u32 data_sn = 0, data_sn_count = 0;
  	u32 pdu_start = 0, seq_no = 0;
  	u32 begrun = dr->begrun;
  	struct iscsi_conn *conn = cmd->conn;
  
  	while (begrun > data_sn++) {
  		data_sn_count++;
  		if ((dr->next_burst_len +
  		     conn->conn_ops->MaxRecvDataSegmentLength) <
  		     conn->sess->sess_ops->MaxBurstLength) {
  			dr->read_data_done +=
  				conn->conn_ops->MaxRecvDataSegmentLength;
  			dr->next_burst_len +=
  				conn->conn_ops->MaxRecvDataSegmentLength;
  		} else {
  			dr->read_data_done +=
  				(conn->sess->sess_ops->MaxBurstLength -
  				 dr->next_burst_len);
  			dr->next_burst_len = 0;
  			pdu_start += data_sn_count;
  			data_sn_count = 0;
  			seq_no++;
  		}
  	}
  
  	if (!conn->sess->sess_ops->DataPDUInOrder) {
  		cmd->seq_no = seq_no;
  		cmd->pdu_start = pdu_start;
  		cmd->pdu_send_order = data_sn_count;
  	}
  
  	return 0;
  }
  
  /*
   *	Generates Offsets and NextBurstLength based on Begrun and Runlength
   *	carried in a Data SNACK or ExpDataSN in TMR TASK_REASSIGN.
   *
   *	For DataSequenceInOrder=No and DataPDUInOrder=[Yes,No] only.
   *
   *	FIXME: How is this handled for a RData SNACK?
   */
  int iscsit_create_recovery_datain_values_datasequenceinorder_no(
  	struct iscsi_cmd *cmd,
  	struct iscsi_datain_req *dr)
  {
  	int found_seq = 0, i;
  	u32 data_sn, read_data_done = 0, seq_send_order = 0;
  	u32 begrun = dr->begrun;
  	u32 runlength = dr->runlength;
  	struct iscsi_conn *conn = cmd->conn;
  	struct iscsi_seq *first_seq = NULL, *seq = NULL;
  
  	if (!cmd->seq_list) {
  		pr_err("struct iscsi_cmd->seq_list is NULL!\n");
  		return -1;
  	}
  
  	/*
  	 * Calculate read_data_done for all sequences containing a
  	 * first_datasn and last_datasn less than the BegRun.
  	 *
  	 * Locate the struct iscsi_seq the BegRun lies within and calculate
  	 * NextBurstLenghth up to the DataSN based on MaxRecvDataSegmentLength.
  	 *
  	 * Also use struct iscsi_seq->seq_send_order to determine where to start.
  	 */
  	for (i = 0; i < cmd->seq_count; i++) {
  		seq = &cmd->seq_list[i];
  
  		if (!seq->seq_send_order)
  			first_seq = seq;
  
  		/*
  		 * No data has been transferred for this DataIN sequence, so the
  		 * seq->first_datasn and seq->last_datasn have not been set.
  		 */
  		if (!seq->sent) {
  			pr_err("Ignoring non-sent sequence 0x%08x ->"
  				" 0x%08x\n\n", seq->first_datasn,
  				seq->last_datasn);
  			continue;
  		}
  
  		/*
  		 * This DataIN sequence is precedes the received BegRun, add the
  		 * total xfer_len of the sequence to read_data_done and reset
  		 * seq->pdu_send_order.
  		 */
  		if ((seq->first_datasn < begrun) &&
  				(seq->last_datasn < begrun)) {
  			pr_err("Pre BegRun sequence 0x%08x ->"
  				" 0x%08x\n", seq->first_datasn,
  				seq->last_datasn);
  
  			read_data_done += cmd->seq_list[i].xfer_len;
  			seq->next_burst_len = seq->pdu_send_order = 0;
  			continue;
  		}
  
  		/*
  		 * The BegRun lies within this DataIN sequence.
  		 */
  		if ((seq->first_datasn <= begrun) &&
  				(seq->last_datasn >= begrun)) {
  			pr_err("Found sequence begrun: 0x%08x in"
  				" 0x%08x -> 0x%08x\n", begrun,
  				seq->first_datasn, seq->last_datasn);
  
  			seq_send_order = seq->seq_send_order;
  			data_sn = seq->first_datasn;
  			seq->next_burst_len = seq->pdu_send_order = 0;
  			found_seq = 1;
  
  			/*
  			 * For DataPDUInOrder=Yes, while the first DataSN of
  			 * the sequence is less than the received BegRun, add
  			 * the MaxRecvDataSegmentLength to read_data_done and
  			 * to the sequence's next_burst_len;
  			 *
  			 * For DataPDUInOrder=No, while the first DataSN of the
  			 * sequence is less than the received BegRun, find the
  			 * struct iscsi_pdu of the DataSN in question and add the
  			 * MaxRecvDataSegmentLength to read_data_done and to the
  			 * sequence's next_burst_len;
  			 */
  			if (conn->sess->sess_ops->DataPDUInOrder) {
  				while (data_sn < begrun) {
  					seq->pdu_send_order++;
  					read_data_done +=
  						conn->conn_ops->MaxRecvDataSegmentLength;
  					seq->next_burst_len +=
  						conn->conn_ops->MaxRecvDataSegmentLength;
  					data_sn++;
  				}
  			} else {
  				int j;
  				struct iscsi_pdu *pdu;
  
  				while (data_sn < begrun) {
  					seq->pdu_send_order++;
  
  					for (j = 0; j < seq->pdu_count; j++) {
  						pdu = &cmd->pdu_list[
  							seq->pdu_start + j];
  						if (pdu->data_sn == data_sn) {
  							read_data_done +=
  								pdu->length;
  							seq->next_burst_len +=
  								pdu->length;
  						}
  					}
  					data_sn++;
  				}
  			}
  			continue;
  		}
  
  		/*
  		 * This DataIN sequence is larger than the received BegRun,
  		 * reset seq->pdu_send_order and continue.
  		 */
  		if ((seq->first_datasn > begrun) ||
  				(seq->last_datasn > begrun)) {
  			pr_err("Post BegRun sequence 0x%08x -> 0x%08x\n",
  					seq->first_datasn, seq->last_datasn);
  
  			seq->next_burst_len = seq->pdu_send_order = 0;
  			continue;
  		}
  	}
  
  	if (!found_seq) {
  		if (!begrun) {
  			if (!first_seq) {
  				pr_err("ITT: 0x%08x, Begrun: 0x%08x"
  					" but first_seq is NULL\n",
  					cmd->init_task_tag, begrun);
  				return -1;
  			}
  			seq_send_order = first_seq->seq_send_order;
  			seq->next_burst_len = seq->pdu_send_order = 0;
  			goto done;
  		}
  
  		pr_err("Unable to locate struct iscsi_seq for ITT: 0x%08x,"
  			" BegRun: 0x%08x, RunLength: 0x%08x while"
  			" DataSequenceInOrder=No and DataPDUInOrder=%s.\n",
  				cmd->init_task_tag, begrun, runlength,
  			(conn->sess->sess_ops->DataPDUInOrder) ? "Yes" : "No");
  		return -1;
  	}
  
  done:
  	dr->read_data_done = read_data_done;
  	dr->seq_send_order = seq_send_order;
  
  	return 0;
  }
  
  static int iscsit_handle_recovery_datain(
  	struct iscsi_cmd *cmd,
  	unsigned char *buf,
  	u32 begrun,
  	u32 runlength)
  {
  	struct iscsi_conn *conn = cmd->conn;
  	struct iscsi_datain_req *dr;
  	struct se_cmd *se_cmd = &cmd->se_cmd;
  
  	if (!(se_cmd->transport_state & CMD_T_COMPLETE)) {
  		pr_err("Ignoring ITT: 0x%08x Data SNACK\n",
  				cmd->init_task_tag);
  		return 0;
  	}
  
  	/*
  	 * Make sure the initiator is not requesting retransmission
  	 * of DataSNs already acknowledged by a Data ACK SNACK.
  	 */
  	if ((cmd->cmd_flags & ICF_GOT_DATACK_SNACK) &&
  	    (begrun <= cmd->acked_data_sn)) {
  		pr_err("ITT: 0x%08x, Data SNACK requesting"
  			" retransmission of DataSN: 0x%08x to 0x%08x but"
  			" already acked to DataSN: 0x%08x by Data ACK SNACK,"
  			" protocol error.\n", cmd->init_task_tag, begrun,
  			(begrun + runlength), cmd->acked_data_sn);
  
  		return iscsit_reject_cmd(cmd, ISCSI_REASON_PROTOCOL_ERROR, buf);
  	}
  
  	/*
  	 * Make sure BegRun and RunLength in the Data SNACK are sane.
  	 * Note: (cmd->data_sn - 1) will carry the maximum DataSN sent.
  	 */
  	if ((begrun + runlength) > (cmd->data_sn - 1)) {
  		pr_err("Initiator requesting BegRun: 0x%08x, RunLength"
  			": 0x%08x greater than maximum DataSN: 0x%08x.\n",
  				begrun, runlength, (cmd->data_sn - 1));
  		return iscsit_reject_cmd(cmd, ISCSI_REASON_BOOKMARK_INVALID,
  					 buf);
  	}
  
  	dr = iscsit_allocate_datain_req();
  	if (!dr)
  		return iscsit_reject_cmd(cmd, ISCSI_REASON_BOOKMARK_NO_RESOURCES,
  					 buf);
  
  	dr->data_sn = dr->begrun = begrun;
  	dr->runlength = runlength;
  	dr->generate_recovery_values = 1;
  	dr->recovery = DATAIN_WITHIN_COMMAND_RECOVERY;
  
  	iscsit_attach_datain_req(cmd, dr);
  
  	cmd->i_state = ISTATE_SEND_DATAIN;
  	iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
  
  	return 0;
  }
  
  int iscsit_handle_recovery_datain_or_r2t(
  	struct iscsi_conn *conn,
  	unsigned char *buf,
  	itt_t init_task_tag,
  	u32 targ_xfer_tag,
  	u32 begrun,
  	u32 runlength)
  {
  	struct iscsi_cmd *cmd;
  
  	cmd = iscsit_find_cmd_from_itt(conn, init_task_tag);
  	if (!cmd)
  		return 0;
  
  	/*
  	 * FIXME: This will not work for bidi commands.
  	 */
  	switch (cmd->data_direction) {
  	case DMA_TO_DEVICE:
  		return iscsit_handle_r2t_snack(cmd, buf, begrun, runlength);
  	case DMA_FROM_DEVICE:
  		return iscsit_handle_recovery_datain(cmd, buf, begrun,
  				runlength);
  	default:
  		pr_err("Unknown cmd->data_direction: 0x%02x\n",
  				cmd->data_direction);
  		return -1;
  	}
  
  	return 0;
  }
  
  /* #warning FIXME: Status SNACK needs to be dependent on OPCODE!!! */
  int iscsit_handle_status_snack(
  	struct iscsi_conn *conn,
  	itt_t init_task_tag,
  	u32 targ_xfer_tag,
  	u32 begrun,
  	u32 runlength)
  {
  	struct iscsi_cmd *cmd = NULL;
  	u32 last_statsn;
  	int found_cmd;
  
  	if (!begrun) {
  		begrun = conn->exp_statsn;
  	} else if (conn->exp_statsn > begrun) {
  		pr_err("Got Status SNACK Begrun: 0x%08x, RunLength:"
  			" 0x%08x but already got ExpStatSN: 0x%08x on CID:"
  			" %hu.\n", begrun, runlength, conn->exp_statsn,
  			conn->cid);
  		return 0;
  	}
  
  	last_statsn = (!runlength) ? conn->stat_sn : (begrun + runlength);
  
  	while (begrun < last_statsn) {
  		found_cmd = 0;
  
  		spin_lock_bh(&conn->cmd_lock);
  		list_for_each_entry(cmd, &conn->conn_cmd_list, i_conn_node) {
  			if (cmd->stat_sn == begrun) {
  				found_cmd = 1;
  				break;
  			}
  		}
  		spin_unlock_bh(&conn->cmd_lock);
  
  		if (!found_cmd) {
  			pr_err("Unable to find StatSN: 0x%08x for"
  				" a Status SNACK, assuming this was a"
  				" protactic SNACK for an untransmitted"
  				" StatSN, ignoring.\n", begrun);
  			begrun++;
  			continue;
  		}
  
  		spin_lock_bh(&cmd->istate_lock);
  		if (cmd->i_state == ISTATE_SEND_DATAIN) {
  			spin_unlock_bh(&cmd->istate_lock);
  			pr_err("Ignoring Status SNACK for BegRun:"
  				" 0x%08x, RunLength: 0x%08x, assuming this was"
  				" a protactic SNACK for an untransmitted"
  				" StatSN\n", begrun, runlength);
  			begrun++;
  			continue;
  		}
  		spin_unlock_bh(&cmd->istate_lock);
  
  		cmd->i_state = ISTATE_SEND_STATUS_RECOVERY;
  		iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
  		begrun++;
  	}
  
  	return 0;
  }
  
  int iscsit_handle_data_ack(
  	struct iscsi_conn *conn,
  	u32 targ_xfer_tag,
  	u32 begrun,
  	u32 runlength)
  {
  	struct iscsi_cmd *cmd = NULL;
  
  	cmd = iscsit_find_cmd_from_ttt(conn, targ_xfer_tag);
  	if (!cmd) {
  		pr_err("Data ACK SNACK for TTT: 0x%08x is"
  			" invalid.\n", targ_xfer_tag);
  		return -1;
  	}
  
  	if (begrun <= cmd->acked_data_sn) {
  		pr_err("ITT: 0x%08x Data ACK SNACK BegRUN: 0x%08x is"
  			" less than the already acked DataSN: 0x%08x.\n",
  			cmd->init_task_tag, begrun, cmd->acked_data_sn);
  		return -1;
  	}
  
  	/*
  	 * For Data ACK SNACK, BegRun is the next expected DataSN.
  	 * (see iSCSI v19: 10.16.6)
  	 */
  	cmd->cmd_flags |= ICF_GOT_DATACK_SNACK;
  	cmd->acked_data_sn = (begrun - 1);
  
  	pr_debug("Received Data ACK SNACK for ITT: 0x%08x,"
  		" updated acked DataSN to 0x%08x.\n",
  			cmd->init_task_tag, cmd->acked_data_sn);
  
  	return 0;
  }
  
  static int iscsit_send_recovery_r2t(
  	struct iscsi_cmd *cmd,
  	u32 offset,
  	u32 xfer_len)
  {
  	int ret;
  
  	spin_lock_bh(&cmd->r2t_lock);
  	ret = iscsit_add_r2t_to_list(cmd, offset, xfer_len, 1, 0);
  	spin_unlock_bh(&cmd->r2t_lock);
  
  	return ret;
  }
  
  int iscsit_dataout_datapduinorder_no_fbit(
  	struct iscsi_cmd *cmd,
  	struct iscsi_pdu *pdu)
  {
  	int i, send_recovery_r2t = 0, recovery = 0;
  	u32 length = 0, offset = 0, pdu_count = 0, xfer_len = 0;
  	struct iscsi_conn *conn = cmd->conn;
  	struct iscsi_pdu *first_pdu = NULL;
  
  	/*
  	 * Get an struct iscsi_pdu pointer to the first PDU, and total PDU count
  	 * of the DataOUT sequence.
  	 */
  	if (conn->sess->sess_ops->DataSequenceInOrder) {
  		for (i = 0; i < cmd->pdu_count; i++) {
  			if (cmd->pdu_list[i].seq_no == pdu->seq_no) {
  				if (!first_pdu)
  					first_pdu = &cmd->pdu_list[i];
  				 xfer_len += cmd->pdu_list[i].length;
  				 pdu_count++;
  			} else if (pdu_count)
  				break;
  		}
  	} else {
  		struct iscsi_seq *seq = cmd->seq_ptr;
  
  		first_pdu = &cmd->pdu_list[seq->pdu_start];
  		pdu_count = seq->pdu_count;
  	}
  
  	if (!first_pdu || !pdu_count)
  		return DATAOUT_CANNOT_RECOVER;
  
  	/*
  	 * Loop through the ending DataOUT Sequence checking each struct iscsi_pdu.
  	 * The following ugly logic does batching of not received PDUs.
  	 */
  	for (i = 0; i < pdu_count; i++) {
  		if (first_pdu[i].status == ISCSI_PDU_RECEIVED_OK) {
  			if (!send_recovery_r2t)
  				continue;
  
  			if (iscsit_send_recovery_r2t(cmd, offset, length) < 0)
  				return DATAOUT_CANNOT_RECOVER;
  
  			send_recovery_r2t = length = offset = 0;
  			continue;
  		}
  		/*
  		 * Set recovery = 1 for any missing, CRC failed, or timed
  		 * out PDUs to let the DataOUT logic know that this sequence
  		 * has not been completed yet.
  		 *
  		 * Also, only send a Recovery R2T for ISCSI_PDU_NOT_RECEIVED.
  		 * We assume if the PDU either failed CRC or timed out
  		 * that a Recovery R2T has already been sent.
  		 */
  		recovery = 1;
  
  		if (first_pdu[i].status != ISCSI_PDU_NOT_RECEIVED)
  			continue;
  
  		if (!offset)
  			offset = first_pdu[i].offset;
  		length += first_pdu[i].length;
  
  		send_recovery_r2t = 1;
  	}
  
  	if (send_recovery_r2t)
  		if (iscsit_send_recovery_r2t(cmd, offset, length) < 0)
  			return DATAOUT_CANNOT_RECOVER;
  
  	return (!recovery) ? DATAOUT_NORMAL : DATAOUT_WITHIN_COMMAND_RECOVERY;
  }
  
  static int iscsit_recalculate_dataout_values(
  	struct iscsi_cmd *cmd,
  	u32 pdu_offset,
  	u32 pdu_length,
  	u32 *r2t_offset,
  	u32 *r2t_length)
  {
  	int i;
  	struct iscsi_conn *conn = cmd->conn;
  	struct iscsi_pdu *pdu = NULL;
  
  	if (conn->sess->sess_ops->DataSequenceInOrder) {
  		cmd->data_sn = 0;
  
  		if (conn->sess->sess_ops->DataPDUInOrder) {
  			*r2t_offset = cmd->write_data_done;
  			*r2t_length = (cmd->seq_end_offset -
  					cmd->write_data_done);
  			return 0;
  		}
  
  		*r2t_offset = cmd->seq_start_offset;
  		*r2t_length = (cmd->seq_end_offset - cmd->seq_start_offset);
  
  		for (i = 0; i < cmd->pdu_count; i++) {
  			pdu = &cmd->pdu_list[i];
  
  			if (pdu->status != ISCSI_PDU_RECEIVED_OK)
  				continue;
  
  			if ((pdu->offset >= cmd->seq_start_offset) &&
  			   ((pdu->offset + pdu->length) <=
  			     cmd->seq_end_offset)) {
  				if (!cmd->unsolicited_data)
  					cmd->next_burst_len -= pdu->length;
  				else
  					cmd->first_burst_len -= pdu->length;
  
  				cmd->write_data_done -= pdu->length;
  				pdu->status = ISCSI_PDU_NOT_RECEIVED;
  			}
  		}
  	} else {
  		struct iscsi_seq *seq = NULL;
  
  		seq = iscsit_get_seq_holder(cmd, pdu_offset, pdu_length);
  		if (!seq)
  			return -1;
  
  		*r2t_offset = seq->orig_offset;
  		*r2t_length = seq->xfer_len;
  
  		cmd->write_data_done -= (seq->offset - seq->orig_offset);
  		if (cmd->immediate_data)
  			cmd->first_burst_len = cmd->write_data_done;
  
  		seq->data_sn = 0;
  		seq->offset = seq->orig_offset;
  		seq->next_burst_len = 0;
  		seq->status = DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY;
  
  		if (conn->sess->sess_ops->DataPDUInOrder)
  			return 0;
  
  		for (i = 0; i < seq->pdu_count; i++) {
  			pdu = &cmd->pdu_list[i+seq->pdu_start];
  
  			if (pdu->status != ISCSI_PDU_RECEIVED_OK)
  				continue;
  
  			pdu->status = ISCSI_PDU_NOT_RECEIVED;
  		}
  	}
  
  	return 0;
  }
  
  int iscsit_recover_dataout_sequence(
  	struct iscsi_cmd *cmd,
  	u32 pdu_offset,
  	u32 pdu_length)
  {
  	u32 r2t_length = 0, r2t_offset = 0;
  
  	spin_lock_bh(&cmd->istate_lock);
  	cmd->cmd_flags |= ICF_WITHIN_COMMAND_RECOVERY;
  	spin_unlock_bh(&cmd->istate_lock);
  
  	if (iscsit_recalculate_dataout_values(cmd, pdu_offset, pdu_length,
  			&r2t_offset, &r2t_length) < 0)
  		return DATAOUT_CANNOT_RECOVER;
  
  	iscsit_send_recovery_r2t(cmd, r2t_offset, r2t_length);
  
  	return DATAOUT_WITHIN_COMMAND_RECOVERY;
  }
  
  static struct iscsi_ooo_cmdsn *iscsit_allocate_ooo_cmdsn(void)
  {
  	struct iscsi_ooo_cmdsn *ooo_cmdsn = NULL;
  
  	ooo_cmdsn = kmem_cache_zalloc(lio_ooo_cache, GFP_ATOMIC);
  	if (!ooo_cmdsn) {
  		pr_err("Unable to allocate memory for"
  			" struct iscsi_ooo_cmdsn.\n");
  		return NULL;
  	}
  	INIT_LIST_HEAD(&ooo_cmdsn->ooo_list);
  
  	return ooo_cmdsn;
  }
  
  /*
   *	Called with sess->cmdsn_mutex held.
   */
  static int iscsit_attach_ooo_cmdsn(
  	struct iscsi_session *sess,
  	struct iscsi_ooo_cmdsn *ooo_cmdsn)
  {
  	struct iscsi_ooo_cmdsn *ooo_tail, *ooo_tmp;
  	/*
  	 * We attach the struct iscsi_ooo_cmdsn entry to the out of order
  	 * list in increasing CmdSN order.
  	 * This allows iscsi_execute_ooo_cmdsns() to detect any
  	 * additional CmdSN holes while performing delayed execution.
  	 */
  	if (list_empty(&sess->sess_ooo_cmdsn_list))
  		list_add_tail(&ooo_cmdsn->ooo_list,
  				&sess->sess_ooo_cmdsn_list);
  	else {
  		ooo_tail = list_entry(sess->sess_ooo_cmdsn_list.prev,
  				typeof(*ooo_tail), ooo_list);
  		/*
  		 * CmdSN is greater than the tail of the list.
  		 */
  		if (iscsi_sna_lt(ooo_tail->cmdsn, ooo_cmdsn->cmdsn))
  			list_add_tail(&ooo_cmdsn->ooo_list,
  					&sess->sess_ooo_cmdsn_list);
  		else {
  			/*
  			 * CmdSN is either lower than the head,  or somewhere
  			 * in the middle.
  			 */
  			list_for_each_entry(ooo_tmp, &sess->sess_ooo_cmdsn_list,
  						ooo_list) {
  				if (iscsi_sna_lt(ooo_tmp->cmdsn, ooo_cmdsn->cmdsn))
  					continue;
  
  				/* Insert before this entry */
  				list_add(&ooo_cmdsn->ooo_list,
  					ooo_tmp->ooo_list.prev);
  				break;
  			}
  		}
  	}
  
  	return 0;
  }
  
  /*
   *	Removes an struct iscsi_ooo_cmdsn from a session's list,
   *	called with struct iscsi_session->cmdsn_mutex held.
   */
  void iscsit_remove_ooo_cmdsn(
  	struct iscsi_session *sess,
  	struct iscsi_ooo_cmdsn *ooo_cmdsn)
  {
  	list_del(&ooo_cmdsn->ooo_list);
  	kmem_cache_free(lio_ooo_cache, ooo_cmdsn);
  }
  
  void iscsit_clear_ooo_cmdsns_for_conn(struct iscsi_conn *conn)
  {
  	struct iscsi_ooo_cmdsn *ooo_cmdsn;
  	struct iscsi_session *sess = conn->sess;
  
  	mutex_lock(&sess->cmdsn_mutex);
  	list_for_each_entry(ooo_cmdsn, &sess->sess_ooo_cmdsn_list, ooo_list) {
  		if (ooo_cmdsn->cid != conn->cid)
  			continue;
  
  		ooo_cmdsn->cmd = NULL;
  	}
  	mutex_unlock(&sess->cmdsn_mutex);
  }
  
  /*
   *	Called with sess->cmdsn_mutex held.
   */
  int iscsit_execute_ooo_cmdsns(struct iscsi_session *sess)
  {
  	int ooo_count = 0;
  	struct iscsi_cmd *cmd = NULL;
  	struct iscsi_ooo_cmdsn *ooo_cmdsn, *ooo_cmdsn_tmp;
  
  	list_for_each_entry_safe(ooo_cmdsn, ooo_cmdsn_tmp,
  				&sess->sess_ooo_cmdsn_list, ooo_list) {
  		if (ooo_cmdsn->cmdsn != sess->exp_cmd_sn)
  			continue;
  
  		if (!ooo_cmdsn->cmd) {
  			sess->exp_cmd_sn++;
  			iscsit_remove_ooo_cmdsn(sess, ooo_cmdsn);
  			continue;
  		}
  
  		cmd = ooo_cmdsn->cmd;
  		cmd->i_state = cmd->deferred_i_state;
  		ooo_count++;
  		sess->exp_cmd_sn++;
  		pr_debug("Executing out of order CmdSN: 0x%08x,"
  			" incremented ExpCmdSN to 0x%08x.\n",
  			cmd->cmd_sn, sess->exp_cmd_sn);
  
  		iscsit_remove_ooo_cmdsn(sess, ooo_cmdsn);
  
  		if (iscsit_execute_cmd(cmd, 1) < 0)
  			return -1;
  
  		continue;
  	}
  
  	return ooo_count;
  }
  
  /*
   *	Called either:
   *
   *	1. With sess->cmdsn_mutex held from iscsi_execute_ooo_cmdsns()
   *	or iscsi_check_received_cmdsn().
   *	2. With no locks held directly from iscsi_handle_XXX_pdu() functions
   *	for immediate commands.
   */
  int iscsit_execute_cmd(struct iscsi_cmd *cmd, int ooo)
  {
  	struct se_cmd *se_cmd = &cmd->se_cmd;
  	struct iscsi_conn *conn = cmd->conn;
  	int lr = 0;
  
  	spin_lock_bh(&cmd->istate_lock);
  	if (ooo)
  		cmd->cmd_flags &= ~ICF_OOO_CMDSN;
  
  	switch (cmd->iscsi_opcode) {
  	case ISCSI_OP_SCSI_CMD:
  		/*
  		 * Go ahead and send the CHECK_CONDITION status for
  		 * any SCSI CDB exceptions that may have occurred.
  		 */
  		if (cmd->sense_reason) {
  			if (cmd->sense_reason == TCM_RESERVATION_CONFLICT) {
  				cmd->i_state = ISTATE_SEND_STATUS;
  				spin_unlock_bh(&cmd->istate_lock);
  				iscsit_add_cmd_to_response_queue(cmd, cmd->conn,
  						cmd->i_state);
  				return 0;
  			}
  			spin_unlock_bh(&cmd->istate_lock);
  			/*
  			 * Determine if delayed TASK_ABORTED status for WRITEs
  			 * should be sent now if no unsolicited data out
  			 * payloads are expected, or if the delayed status
  			 * should be sent after unsolicited data out with
  			 * ISCSI_FLAG_CMD_FINAL set in iscsi_handle_data_out()
  			 */
  			if (transport_check_aborted_status(se_cmd,
  					(cmd->unsolicited_data == 0)) != 0)
  				return 0;
  			/*
  			 * Otherwise send CHECK_CONDITION and sense for
  			 * exception
  			 */
  			return transport_send_check_condition_and_sense(se_cmd,
  					cmd->sense_reason, 0);
  		}
  		/*
  		 * Special case for delayed CmdSN with Immediate
  		 * Data and/or Unsolicited Data Out attached.
  		 */
  		if (cmd->immediate_data) {
  			if (cmd->cmd_flags & ICF_GOT_LAST_DATAOUT) {
  				spin_unlock_bh(&cmd->istate_lock);
  				target_execute_cmd(&cmd->se_cmd);
  				return 0;
  			}
  			spin_unlock_bh(&cmd->istate_lock);
  
  			if (!(cmd->cmd_flags &
  					ICF_NON_IMMEDIATE_UNSOLICITED_DATA)) {
  				/*
  				 * Send the delayed TASK_ABORTED status for
  				 * WRITEs if no more unsolicitied data is
  				 * expected.
  				 */
  				if (transport_check_aborted_status(se_cmd, 1)
  						!= 0)
  					return 0;
  
  				iscsit_set_dataout_sequence_values(cmd);
  				conn->conn_transport->iscsit_get_dataout(conn, cmd, false);
  			}
  			return 0;
  		}
  		/*
  		 * The default handler.
  		 */
  		spin_unlock_bh(&cmd->istate_lock);
  
  		if ((cmd->data_direction == DMA_TO_DEVICE) &&
  		    !(cmd->cmd_flags & ICF_NON_IMMEDIATE_UNSOLICITED_DATA)) {
  			/*
  			 * Send the delayed TASK_ABORTED status for WRITEs if
  			 * no more nsolicitied data is expected.
  			 */
  			if (transport_check_aborted_status(se_cmd, 1) != 0)
  				return 0;
  
  			iscsit_set_unsoliticed_dataout(cmd);
  		}
  		return transport_handle_cdb_direct(&cmd->se_cmd);
  
  	case ISCSI_OP_NOOP_OUT:
  	case ISCSI_OP_TEXT:
  		spin_unlock_bh(&cmd->istate_lock);
  		iscsit_add_cmd_to_response_queue(cmd, cmd->conn, cmd->i_state);
  		break;
  	case ISCSI_OP_SCSI_TMFUNC:
  		if (cmd->se_cmd.se_tmr_req->response) {
  			spin_unlock_bh(&cmd->istate_lock);
  			iscsit_add_cmd_to_response_queue(cmd, cmd->conn,
  					cmd->i_state);
  			return 0;
  		}
  		spin_unlock_bh(&cmd->istate_lock);
  
  		return transport_generic_handle_tmr(&cmd->se_cmd);
  	case ISCSI_OP_LOGOUT:
  		spin_unlock_bh(&cmd->istate_lock);
  		switch (cmd->logout_reason) {
  		case ISCSI_LOGOUT_REASON_CLOSE_SESSION:
  			lr = iscsit_logout_closesession(cmd, cmd->conn);
  			break;
  		case ISCSI_LOGOUT_REASON_CLOSE_CONNECTION:
  			lr = iscsit_logout_closeconnection(cmd, cmd->conn);
  			break;
  		case ISCSI_LOGOUT_REASON_RECOVERY:
  			lr = iscsit_logout_removeconnforrecovery(cmd, cmd->conn);
  			break;
  		default:
  			pr_err("Unknown iSCSI Logout Request Code:"
  				" 0x%02x\n", cmd->logout_reason);
  			return -1;
  		}
  
  		return lr;
  	default:
  		spin_unlock_bh(&cmd->istate_lock);
  		pr_err("Cannot perform out of order execution for"
  		" unknown iSCSI Opcode: 0x%02x\n", cmd->iscsi_opcode);
  		return -1;
  	}
  
  	return 0;
  }
  
  void iscsit_free_all_ooo_cmdsns(struct iscsi_session *sess)
  {
  	struct iscsi_ooo_cmdsn *ooo_cmdsn, *ooo_cmdsn_tmp;
  
  	mutex_lock(&sess->cmdsn_mutex);
  	list_for_each_entry_safe(ooo_cmdsn, ooo_cmdsn_tmp,
  			&sess->sess_ooo_cmdsn_list, ooo_list) {
  
  		list_del(&ooo_cmdsn->ooo_list);
  		kmem_cache_free(lio_ooo_cache, ooo_cmdsn);
  	}
  	mutex_unlock(&sess->cmdsn_mutex);
  }
  
  int iscsit_handle_ooo_cmdsn(
  	struct iscsi_session *sess,
  	struct iscsi_cmd *cmd,
  	u32 cmdsn)
  {
  	int batch = 0;
  	struct iscsi_ooo_cmdsn *ooo_cmdsn = NULL, *ooo_tail = NULL;
  
  	cmd->deferred_i_state		= cmd->i_state;
  	cmd->i_state			= ISTATE_DEFERRED_CMD;
  	cmd->cmd_flags			|= ICF_OOO_CMDSN;
  
  	if (list_empty(&sess->sess_ooo_cmdsn_list))
  		batch = 1;
  	else {
  		ooo_tail = list_entry(sess->sess_ooo_cmdsn_list.prev,
  				typeof(*ooo_tail), ooo_list);
  		if (ooo_tail->cmdsn != (cmdsn - 1))
  			batch = 1;
  	}
  
  	ooo_cmdsn = iscsit_allocate_ooo_cmdsn();
  	if (!ooo_cmdsn)
  		return -ENOMEM;
  
  	ooo_cmdsn->cmd			= cmd;
  	ooo_cmdsn->batch_count		= (batch) ?
  					  (cmdsn - sess->exp_cmd_sn) : 1;
  	ooo_cmdsn->cid			= cmd->conn->cid;
  	ooo_cmdsn->exp_cmdsn		= sess->exp_cmd_sn;
  	ooo_cmdsn->cmdsn		= cmdsn;
  
  	if (iscsit_attach_ooo_cmdsn(sess, ooo_cmdsn) < 0) {
  		kmem_cache_free(lio_ooo_cache, ooo_cmdsn);
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  static int iscsit_set_dataout_timeout_values(
  	struct iscsi_cmd *cmd,
  	u32 *offset,
  	u32 *length)
  {
  	struct iscsi_conn *conn = cmd->conn;
  	struct iscsi_r2t *r2t;
  
  	if (cmd->unsolicited_data) {
  		*offset = 0;
  		*length = (conn->sess->sess_ops->FirstBurstLength >
  			   cmd->se_cmd.data_length) ?
  			   cmd->se_cmd.data_length :
  			   conn->sess->sess_ops->FirstBurstLength;
  		return 0;
  	}
  
  	spin_lock_bh(&cmd->r2t_lock);
  	if (list_empty(&cmd->cmd_r2t_list)) {
  		pr_err("cmd->cmd_r2t_list is empty!\n");
  		spin_unlock_bh(&cmd->r2t_lock);
  		return -1;
  	}
  
  	list_for_each_entry(r2t, &cmd->cmd_r2t_list, r2t_list) {
  		if (r2t->sent_r2t && !r2t->recovery_r2t && !r2t->seq_complete) {
  			*offset = r2t->offset;
  			*length = r2t->xfer_len;
  			spin_unlock_bh(&cmd->r2t_lock);
  			return 0;
  		}
  	}
  	spin_unlock_bh(&cmd->r2t_lock);
  
  	pr_err("Unable to locate any incomplete DataOUT"
  		" sequences for ITT: 0x%08x.\n", cmd->init_task_tag);
  
  	return -1;
  }
  
  /*
   *	NOTE: Called from interrupt (timer) context.
   */
  static void iscsit_handle_dataout_timeout(unsigned long data)
  {
  	u32 pdu_length = 0, pdu_offset = 0;
  	u32 r2t_length = 0, r2t_offset = 0;
  	struct iscsi_cmd *cmd = (struct iscsi_cmd *) data;
  	struct iscsi_conn *conn = cmd->conn;
  	struct iscsi_session *sess = NULL;
  	struct iscsi_node_attrib *na;
  
  	iscsit_inc_conn_usage_count(conn);
  
  	spin_lock_bh(&cmd->dataout_timeout_lock);
  	if (cmd->dataout_timer_flags & ISCSI_TF_STOP) {
  		spin_unlock_bh(&cmd->dataout_timeout_lock);
  		iscsit_dec_conn_usage_count(conn);
  		return;
  	}
  	cmd->dataout_timer_flags &= ~ISCSI_TF_RUNNING;
  	sess = conn->sess;
  	na = iscsit_tpg_get_node_attrib(sess);
  
  	if (!sess->sess_ops->ErrorRecoveryLevel) {
  		pr_debug("Unable to recover from DataOut timeout while"
  			" in ERL=0.\n");
  		goto failure;
  	}
  
  	if (++cmd->dataout_timeout_retries == na->dataout_timeout_retries) {
  		pr_debug("Command ITT: 0x%08x exceeded max retries"
  			" for DataOUT timeout %u, closing iSCSI connection.\n",
  			cmd->init_task_tag, na->dataout_timeout_retries);
  		goto failure;
  	}
  
  	cmd->cmd_flags |= ICF_WITHIN_COMMAND_RECOVERY;
  
  	if (conn->sess->sess_ops->DataSequenceInOrder) {
  		if (conn->sess->sess_ops->DataPDUInOrder) {
  			pdu_offset = cmd->write_data_done;
  			if ((pdu_offset + (conn->sess->sess_ops->MaxBurstLength -
  			     cmd->next_burst_len)) > cmd->se_cmd.data_length)
  				pdu_length = (cmd->se_cmd.data_length -
  					cmd->write_data_done);
  			else
  				pdu_length = (conn->sess->sess_ops->MaxBurstLength -
  						cmd->next_burst_len);
  		} else {
  			pdu_offset = cmd->seq_start_offset;
  			pdu_length = (cmd->seq_end_offset -
  				cmd->seq_start_offset);
  		}
  	} else {
  		if (iscsit_set_dataout_timeout_values(cmd, &pdu_offset,
  				&pdu_length) < 0)
  			goto failure;
  	}
  
  	if (iscsit_recalculate_dataout_values(cmd, pdu_offset, pdu_length,
  			&r2t_offset, &r2t_length) < 0)
  		goto failure;
  
  	pr_debug("Command ITT: 0x%08x timed out waiting for"
  		" completion of %sDataOUT Sequence Offset: %u, Length: %u\n",
  		cmd->init_task_tag, (cmd->unsolicited_data) ? "Unsolicited " :
  		"", r2t_offset, r2t_length);
  
  	if (iscsit_send_recovery_r2t(cmd, r2t_offset, r2t_length) < 0)
  		goto failure;
  
  	iscsit_start_dataout_timer(cmd, conn);
  	spin_unlock_bh(&cmd->dataout_timeout_lock);
  	iscsit_dec_conn_usage_count(conn);
  
  	return;
  
  failure:
  	spin_unlock_bh(&cmd->dataout_timeout_lock);
  	iscsit_cause_connection_reinstatement(conn, 0);
  	iscsit_dec_conn_usage_count(conn);
  }
  
  void iscsit_mod_dataout_timer(struct iscsi_cmd *cmd)
  {
  	struct iscsi_conn *conn = cmd->conn;
  	struct iscsi_session *sess = conn->sess;
  	struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);
  
  	spin_lock_bh(&cmd->dataout_timeout_lock);
  	if (!(cmd->dataout_timer_flags & ISCSI_TF_RUNNING)) {
  		spin_unlock_bh(&cmd->dataout_timeout_lock);
  		return;
  	}
  
  	mod_timer(&cmd->dataout_timer,
  		(get_jiffies_64() + na->dataout_timeout * HZ));
  	pr_debug("Updated DataOUT timer for ITT: 0x%08x",
  			cmd->init_task_tag);
  	spin_unlock_bh(&cmd->dataout_timeout_lock);
  }
  
  /*
   *	Called with cmd->dataout_timeout_lock held.
   */
  void iscsit_start_dataout_timer(
  	struct iscsi_cmd *cmd,
  	struct iscsi_conn *conn)
  {
  	struct iscsi_session *sess = conn->sess;
  	struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);
  
  	if (cmd->dataout_timer_flags & ISCSI_TF_RUNNING)
  		return;
  
  	pr_debug("Starting DataOUT timer for ITT: 0x%08x on"
  		" CID: %hu.\n", cmd->init_task_tag, conn->cid);
  
  	init_timer(&cmd->dataout_timer);
  	cmd->dataout_timer.expires = (get_jiffies_64() + na->dataout_timeout * HZ);
  	cmd->dataout_timer.data = (unsigned long)cmd;
  	cmd->dataout_timer.function = iscsit_handle_dataout_timeout;
  	cmd->dataout_timer_flags &= ~ISCSI_TF_STOP;
  	cmd->dataout_timer_flags |= ISCSI_TF_RUNNING;
  	add_timer(&cmd->dataout_timer);
  }
  
  void iscsit_stop_dataout_timer(struct iscsi_cmd *cmd)
  {
  	spin_lock_bh(&cmd->dataout_timeout_lock);
  	if (!(cmd->dataout_timer_flags & ISCSI_TF_RUNNING)) {
  		spin_unlock_bh(&cmd->dataout_timeout_lock);
  		return;
  	}
  	cmd->dataout_timer_flags |= ISCSI_TF_STOP;
  	spin_unlock_bh(&cmd->dataout_timeout_lock);
  
  	del_timer_sync(&cmd->dataout_timer);
  
  	spin_lock_bh(&cmd->dataout_timeout_lock);
  	cmd->dataout_timer_flags &= ~ISCSI_TF_RUNNING;
  	pr_debug("Stopped DataOUT Timer for ITT: 0x%08x\n",
  			cmd->init_task_tag);
  	spin_unlock_bh(&cmd->dataout_timeout_lock);
  }
  EXPORT_SYMBOL(iscsit_stop_dataout_timer);
  