// SPDX-License-Identifier: GPL-2.0-or-later
/*******************************************************************************
 * Filename: target_core_xcopy.c
 *
 * This file contains support for SPC-4 Extended-Copy offload with generic
 * TCM backends.
 *
 * Copyright (c) 2011-2013 Datera, Inc. All rights reserved.
 *
 * Author:
 * Nicholas A. Bellinger <nab@daterainc.com>
 *
 ******************************************************************************/

#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/configfs.h>
#include <linux/ratelimit.h>
#include <scsi/scsi_proto.h>
#include <linux/unaligned.h>

#include <target/target_core_base.h>
#include <target/target_core_backend.h>
#include <target/target_core_fabric.h>

#include "target_core_internal.h"
#include "target_core_pr.h"
#include "target_core_ua.h"
#include "target_core_xcopy.h"

static struct workqueue_struct *xcopy_wq = NULL;

static sense_reason_t target_parse_xcopy_cmd(struct xcopy_op *xop);

/**
 * target_xcopy_locate_se_dev_e4_iter - compare XCOPY NAA device identifiers
 *
 * @se_dev: device being considered for match
 * @dev_wwn: XCOPY requested NAA dev_wwn
 * @return: 1 on match, 0 on no-match
 */
static int target_xcopy_locate_se_dev_e4_iter(struct se_device *se_dev,
                                              const unsigned char *dev_wwn)
{
        unsigned char tmp_dev_wwn[XCOPY_NAA_IEEE_REGEX_LEN];
        int rc;

        if (!se_dev->dev_attrib.emulate_3pc) {
                pr_debug("XCOPY: emulate_3pc disabled on se_dev %p\n", se_dev);
                return 0;
        }

        memset(&tmp_dev_wwn[0], 0, XCOPY_NAA_IEEE_REGEX_LEN);
        spc_gen_naa_6h_vendor_specific(se_dev, &tmp_dev_wwn[0]);

        rc = memcmp(&tmp_dev_wwn[0], dev_wwn, XCOPY_NAA_IEEE_REGEX_LEN);
        if (rc != 0) {
                pr_debug("XCOPY: skip non-matching: %*ph\n",
                         XCOPY_NAA_IEEE_REGEX_LEN, tmp_dev_wwn);
                return 0;
        }
        pr_debug("XCOPY 0xe4: located se_dev: %p\n", se_dev);

        return 1;
}

static int target_xcopy_locate_se_dev_e4(struct se_session *sess,
                                        const unsigned char *dev_wwn,
                                        struct se_device **_found_dev,
                                        struct percpu_ref **_found_lun_ref)
{
        struct se_dev_entry *deve;
        struct se_node_acl *nacl;
        struct se_lun *this_lun = NULL;
        struct se_device *found_dev = NULL;

        /* cmd with NULL sess indicates no associated $FABRIC_MOD */
        if (!sess)
                goto err_out;

        pr_debug("XCOPY 0xe4: searching for: %*ph\n",
                 XCOPY_NAA_IEEE_REGEX_LEN, dev_wwn);

        nacl = sess->se_node_acl;
        rcu_read_lock();
        hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link) {
                struct se_device *this_dev;
                int rc;

                this_lun = deve->se_lun;
                this_dev = rcu_dereference_raw(this_lun->lun_se_dev);

                rc = target_xcopy_locate_se_dev_e4_iter(this_dev, dev_wwn);
                if (rc) {
                        if (percpu_ref_tryget_live(&this_lun->lun_ref))
                                found_dev = this_dev;
                        break;
                }
        }
        rcu_read_unlock();
        if (found_dev == NULL)
                goto err_out;

        pr_debug("lun_ref held for se_dev: %p se_dev->se_dev_group: %p\n",
                 found_dev, &found_dev->dev_group);
        *_found_dev = found_dev;
        *_found_lun_ref = &this_lun->lun_ref;
        return 0;
err_out:
        pr_debug_ratelimited("Unable to locate 0xe4 descriptor for EXTENDED_COPY\n");
        return -EINVAL;
}

static int target_xcopy_parse_tiddesc_e4(struct se_cmd *se_cmd, struct xcopy_op *xop,
                                unsigned char *p, unsigned short cscd_index)
{
        unsigned char *desc = p;
        unsigned short ript;
        u8 desig_len;
        /*
         * Extract RELATIVE INITIATOR PORT IDENTIFIER
         */
        ript = get_unaligned_be16(&desc[2]);
        pr_debug("XCOPY 0xe4: RELATIVE INITIATOR PORT IDENTIFIER: %hu\n", ript);
        /*
         * Check for supported code set, association, and designator type
         */
        if ((desc[4] & 0x0f) != 0x1) {
                pr_err("XCOPY 0xe4: code set of non binary type not supported\n");
                return -EINVAL;
        }
        if ((desc[5] & 0x30) != 0x00) {
                pr_err("XCOPY 0xe4: association other than LUN not supported\n");
                return -EINVAL;
        }
        if ((desc[5] & 0x0f) != 0x3) {
                pr_err("XCOPY 0xe4: designator type unsupported: 0x%02x\n",
                                (desc[5] & 0x0f));
                return -EINVAL;
        }
        /*
         * Check for matching 16 byte length for NAA IEEE Registered Extended
         * Assigned designator
         */
        desig_len = desc[7];
        if (desig_len != XCOPY_NAA_IEEE_REGEX_LEN) {
                pr_err("XCOPY 0xe4: invalid desig_len: %d\n", (int)desig_len);
                return -EINVAL;
        }
        pr_debug("XCOPY 0xe4: desig_len: %d\n", (int)desig_len);
        /*
         * Check for NAA IEEE Registered Extended Assigned header..
         */
        if ((desc[8] & 0xf0) != 0x60) {
                pr_err("XCOPY 0xe4: Unsupported DESIGNATOR TYPE: 0x%02x\n",
                                        (desc[8] & 0xf0));
                return -EINVAL;
        }

        if (cscd_index != xop->stdi && cscd_index != xop->dtdi) {
                pr_debug("XCOPY 0xe4: ignoring CSCD entry %d - neither src nor "
                         "dest\n", cscd_index);
                return 0;
        }

        if (cscd_index == xop->stdi) {
                memcpy(&xop->src_tid_wwn[0], &desc[8], XCOPY_NAA_IEEE_REGEX_LEN);
                /*
                 * Determine if the source designator matches the local device
                 */
                if (!memcmp(&xop->local_dev_wwn[0], &xop->src_tid_wwn[0],
                                XCOPY_NAA_IEEE_REGEX_LEN)) {
                        xop->op_origin = XCOL_SOURCE_RECV_OP;
                        xop->src_dev = se_cmd->se_dev;
                        pr_debug("XCOPY 0xe4: Set xop->src_dev %p from source"
                                        " received xop\n", xop->src_dev);
                }
        }

        if (cscd_index == xop->dtdi) {
                memcpy(&xop->dst_tid_wwn[0], &desc[8], XCOPY_NAA_IEEE_REGEX_LEN);
                /*
                 * Determine if the destination designator matches the local
                 * device. If @cscd_index corresponds to both source (stdi) and
                 * destination (dtdi), or dtdi comes after stdi, then
                 * XCOL_DEST_RECV_OP wins.
                 */
                if (!memcmp(&xop->local_dev_wwn[0], &xop->dst_tid_wwn[0],
                                XCOPY_NAA_IEEE_REGEX_LEN)) {
                        xop->op_origin = XCOL_DEST_RECV_OP;
                        xop->dst_dev = se_cmd->se_dev;
                        pr_debug("XCOPY 0xe4: Set xop->dst_dev: %p from destination"
                                " received xop\n", xop->dst_dev);
                }
        }

        return 0;
}

static int target_xcopy_parse_target_descriptors(struct se_cmd *se_cmd,
                                struct xcopy_op *xop, unsigned char *p,
                                unsigned short tdll, sense_reason_t *sense_ret)
{
        struct se_device *local_dev = se_cmd->se_dev;
        unsigned char *desc = p;
        int offset = tdll % XCOPY_TARGET_DESC_LEN, rc;
        unsigned short cscd_index = 0;
        unsigned short start = 0;

        *sense_ret = TCM_INVALID_PARAMETER_LIST;

        if (offset != 0) {
                pr_err("XCOPY target descriptor list length is not"
                        " multiple of %d\n", XCOPY_TARGET_DESC_LEN);
                *sense_ret = TCM_UNSUPPORTED_TARGET_DESC_TYPE_CODE;
                return -EINVAL;
        }
        if (tdll > RCR_OP_MAX_TARGET_DESC_COUNT * XCOPY_TARGET_DESC_LEN) {
                pr_err("XCOPY target descriptor supports a maximum"
                        " two src/dest descriptors, tdll: %hu too large..\n", tdll);
                /* spc4r37 6.4.3.4 CSCD DESCRIPTOR LIST LENGTH field */
                *sense_ret = TCM_TOO_MANY_TARGET_DESCS;
                return -EINVAL;
        }
        /*
         * Generate an IEEE Registered Extended designator based upon the
         * se_device the XCOPY was received upon..
         */
        memset(&xop->local_dev_wwn[0], 0, XCOPY_NAA_IEEE_REGEX_LEN);
        spc_gen_naa_6h_vendor_specific(local_dev, &xop->local_dev_wwn[0]);

        while (start < tdll) {
                /*
                 * Check target descriptor identification with 0xE4 type, and
                 * compare the current index with the CSCD descriptor IDs in
                 * the segment descriptor. Use VPD 0x83 WWPN matching ..
                 */
                switch (desc[0]) {
                case 0xe4:
                        rc = target_xcopy_parse_tiddesc_e4(se_cmd, xop,
                                                        &desc[0], cscd_index);
                        if (rc != 0)
                                goto out;
                        start += XCOPY_TARGET_DESC_LEN;
                        desc += XCOPY_TARGET_DESC_LEN;
                        cscd_index++;
                        break;
                default:
                        pr_err("XCOPY unsupported descriptor type code:"
                                        " 0x%02x\n", desc[0]);
                        *sense_ret = TCM_UNSUPPORTED_TARGET_DESC_TYPE_CODE;
                        goto out;
                }
        }

        switch (xop->op_origin) {
        case XCOL_SOURCE_RECV_OP:
                rc = target_xcopy_locate_se_dev_e4(se_cmd->se_sess,
                                                xop->dst_tid_wwn,
                                                &xop->dst_dev,
                                                &xop->remote_lun_ref);
                break;
        case XCOL_DEST_RECV_OP:
                rc = target_xcopy_locate_se_dev_e4(se_cmd->se_sess,
                                                xop->src_tid_wwn,
                                                &xop->src_dev,
                                                &xop->remote_lun_ref);
                break;
        default:
                pr_err("XCOPY CSCD descriptor IDs not found in CSCD list - "
                        "stdi: %hu dtdi: %hu\n", xop->stdi, xop->dtdi);
                rc = -EINVAL;
                break;
        }
        /*
         * If a matching IEEE NAA 0x83 descriptor for the requested device
         * is not located on this node, return COPY_ABORTED with ASQ/ASQC
         * 0x0d/0x02 - COPY_TARGET_DEVICE_NOT_REACHABLE to request the
         * initiator to fall back to normal copy method.
         */
        if (rc < 0) {
                *sense_ret = TCM_COPY_TARGET_DEVICE_NOT_REACHABLE;
                goto out;
        }

        pr_debug("XCOPY TGT desc: Source dev: %p NAA IEEE WWN: 0x%16phN\n",
                 xop->src_dev, &xop->src_tid_wwn[0]);
        pr_debug("XCOPY TGT desc: Dest dev: %p NAA IEEE WWN: 0x%16phN\n",
                 xop->dst_dev, &xop->dst_tid_wwn[0]);

        return cscd_index;

out:
        return -EINVAL;
}

static int target_xcopy_parse_segdesc_02(struct xcopy_op *xop, unsigned char *p)
{
        unsigned char *desc = p;
        int dc = (desc[1] & 0x02);
        unsigned short desc_len;

        desc_len = get_unaligned_be16(&desc[2]);
        if (desc_len != 0x18) {
                pr_err("XCOPY segment desc 0x02: Illegal desc_len:"
                                " %hu\n", desc_len);
                return -EINVAL;
        }

        xop->stdi = get_unaligned_be16(&desc[4]);
        xop->dtdi = get_unaligned_be16(&desc[6]);

        if (xop->stdi > XCOPY_CSCD_DESC_ID_LIST_OFF_MAX ||
            xop->dtdi > XCOPY_CSCD_DESC_ID_LIST_OFF_MAX) {
                pr_err("XCOPY segment desc 0x02: unsupported CSCD ID > 0x%x; stdi: %hu dtdi: %hu\n",
                        XCOPY_CSCD_DESC_ID_LIST_OFF_MAX, xop->stdi, xop->dtdi);
                return -EINVAL;
        }

        pr_debug("XCOPY seg desc 0x02: desc_len: %hu stdi: %hu dtdi: %hu, DC: %d\n",
                desc_len, xop->stdi, xop->dtdi, dc);

        xop->nolb = get_unaligned_be16(&desc[10]);
        xop->src_lba = get_unaligned_be64(&desc[12]);
        xop->dst_lba = get_unaligned_be64(&desc[20]);
        pr_debug("XCOPY seg desc 0x02: nolb: %hu src_lba: %llu dst_lba: %llu\n",
                xop->nolb, (unsigned long long)xop->src_lba,
                (unsigned long long)xop->dst_lba);

        return 0;
}

static int target_xcopy_parse_segment_descriptors(struct xcopy_op *xop,
                                unsigned char *p, unsigned int sdll,
                                sense_reason_t *sense_ret)
{
        unsigned char *desc = p;
        unsigned int start = 0;
        int offset = sdll % XCOPY_SEGMENT_DESC_LEN, rc, ret = 0;

        *sense_ret = TCM_INVALID_PARAMETER_LIST;

        if (offset != 0) {
                pr_err("XCOPY segment descriptor list length is not"
                        " multiple of %d\n", XCOPY_SEGMENT_DESC_LEN);
                *sense_ret = TCM_UNSUPPORTED_SEGMENT_DESC_TYPE_CODE;
                return -EINVAL;
        }
        if (sdll > RCR_OP_MAX_SG_DESC_COUNT * XCOPY_SEGMENT_DESC_LEN) {
                pr_err("XCOPY supports %u segment descriptor(s), sdll: %u too"
                        " large..\n", RCR_OP_MAX_SG_DESC_COUNT, sdll);
                /* spc4r37 6.4.3.5 SEGMENT DESCRIPTOR LIST LENGTH field */
                *sense_ret = TCM_TOO_MANY_SEGMENT_DESCS;
                return -EINVAL;
        }

        while (start < sdll) {
                /*
                 * Check segment descriptor type code for block -> block
                 */
                switch (desc[0]) {
                case 0x02:
                        rc = target_xcopy_parse_segdesc_02(xop, desc);
                        if (rc < 0)
                                goto out;

                        ret++;
                        start += XCOPY_SEGMENT_DESC_LEN;
                        desc += XCOPY_SEGMENT_DESC_LEN;
                        break;
                default:
                        pr_err("XCOPY unsupported segment descriptor"
                                "type: 0x%02x\n", desc[0]);
                        *sense_ret = TCM_UNSUPPORTED_SEGMENT_DESC_TYPE_CODE;
                        goto out;
                }
        }

        return ret;

out:
        return -EINVAL;
}

/*
 * Start xcopy_pt ops
 */

struct xcopy_pt_cmd {
        struct se_cmd se_cmd;
        struct completion xpt_passthrough_sem;
        unsigned char sense_buffer[TRANSPORT_SENSE_BUFFER];
};

struct se_portal_group xcopy_pt_tpg;
static struct se_session xcopy_pt_sess;
static struct se_node_acl xcopy_pt_nacl;

static int xcopy_pt_get_cmd_state(struct se_cmd *se_cmd)
{
        return 0;
}

static void xcopy_pt_undepend_remotedev(struct xcopy_op *xop)
{
        if (xop->op_origin == XCOL_SOURCE_RECV_OP)
                pr_debug("putting dst lun_ref for %p\n", xop->dst_dev);
        else
                pr_debug("putting src lun_ref for %p\n", xop->src_dev);

        percpu_ref_put(xop->remote_lun_ref);
}

static void xcopy_pt_release_cmd(struct se_cmd *se_cmd)
{
        struct xcopy_pt_cmd *xpt_cmd = container_of(se_cmd,
                                struct xcopy_pt_cmd, se_cmd);

        /* xpt_cmd is on the stack, nothing to free here */
        pr_debug("xpt_cmd done: %p\n", xpt_cmd);
}

static int xcopy_pt_check_stop_free(struct se_cmd *se_cmd)
{
        struct xcopy_pt_cmd *xpt_cmd = container_of(se_cmd,
                                struct xcopy_pt_cmd, se_cmd);

        complete(&xpt_cmd->xpt_passthrough_sem);
        return 0;
}

static int xcopy_pt_write_pending(struct se_cmd *se_cmd)
{
        return 0;
}

static int xcopy_pt_queue_data_in(struct se_cmd *se_cmd)
{
        return 0;
}

static int xcopy_pt_queue_status(struct se_cmd *se_cmd)
{
        return 0;
}

static const struct target_core_fabric_ops xcopy_pt_tfo = {
        .fabric_name            = "xcopy-pt",
        .get_cmd_state          = xcopy_pt_get_cmd_state,
        .release_cmd            = xcopy_pt_release_cmd,
        .check_stop_free        = xcopy_pt_check_stop_free,
        .write_pending          = xcopy_pt_write_pending,
        .queue_data_in          = xcopy_pt_queue_data_in,
        .queue_status           = xcopy_pt_queue_status,
};

/*
 * End xcopy_pt_ops
 */

int target_xcopy_setup_pt(void)
{
        xcopy_wq = alloc_workqueue("xcopy_wq", WQ_MEM_RECLAIM | WQ_PERCPU, 0);
        if (!xcopy_wq) {
                pr_err("Unable to allocate xcopy_wq\n");
                return -ENOMEM;
        }

        memset(&xcopy_pt_tpg, 0, sizeof(struct se_portal_group));
        INIT_LIST_HEAD(&xcopy_pt_tpg.acl_node_list);
        INIT_LIST_HEAD(&xcopy_pt_tpg.tpg_sess_list);

        xcopy_pt_tpg.se_tpg_tfo = &xcopy_pt_tfo;

        memset(&xcopy_pt_nacl, 0, sizeof(struct se_node_acl));
        INIT_LIST_HEAD(&xcopy_pt_nacl.acl_list);
        INIT_LIST_HEAD(&xcopy_pt_nacl.acl_sess_list);
        memset(&xcopy_pt_sess, 0, sizeof(struct se_session));
        transport_init_session(&xcopy_pt_sess);

        xcopy_pt_nacl.se_tpg = &xcopy_pt_tpg;
        xcopy_pt_nacl.nacl_sess = &xcopy_pt_sess;

        xcopy_pt_sess.se_tpg = &xcopy_pt_tpg;
        xcopy_pt_sess.se_node_acl = &xcopy_pt_nacl;

        return 0;
}

void target_xcopy_release_pt(void)
{
        if (xcopy_wq)
                destroy_workqueue(xcopy_wq);
}

/*
 * target_xcopy_setup_pt_cmd - set up a pass-through command
 * @xpt_cmd:     Data structure to initialize.
 * @xop:         Describes the XCOPY operation received from an initiator.
 * @se_dev:      Backend device to associate with @xpt_cmd if
 *               @remote_port == true.
 * @cdb:         SCSI CDB to be copied into @xpt_cmd.
 * @remote_port: If false, use the LUN through which the XCOPY command has
 *               been received. If true, use @se_dev->xcopy_lun.
 *
 * Set up a SCSI command (READ or WRITE) that will be used to execute an
 * XCOPY command.
 */
static int target_xcopy_setup_pt_cmd(
        struct xcopy_pt_cmd *xpt_cmd,
        struct xcopy_op *xop,
        struct se_device *se_dev,
        unsigned char *cdb,
        bool remote_port)
{
        struct se_cmd *cmd = &xpt_cmd->se_cmd;

        /*
         * Setup LUN+port to honor reservations based upon xop->op_origin for
         * X-COPY PUSH or X-COPY PULL based upon where the CDB was received.
         */
        if (remote_port) {
                cmd->se_lun = &se_dev->xcopy_lun;
                cmd->se_dev = se_dev;
        } else {
                cmd->se_lun = xop->xop_se_cmd->se_lun;
                cmd->se_dev = xop->xop_se_cmd->se_dev;
        }
        cmd->se_cmd_flags |= SCF_SE_LUN_CMD;

        if (target_cmd_init_cdb(cmd, cdb, GFP_KERNEL))
                return -EINVAL;

        cmd->tag = 0;
        if (target_cmd_parse_cdb(cmd))
                return -EINVAL;

        if (transport_generic_map_mem_to_cmd(cmd, xop->xop_data_sg,
                                        xop->xop_data_nents, NULL, 0))
                return -EINVAL;

        pr_debug("Setup PASSTHROUGH_NOALLOC t_data_sg: %p t_data_nents:"
                 " %u\n", cmd->t_data_sg, cmd->t_data_nents);

        return 0;
}

static int target_xcopy_issue_pt_cmd(struct xcopy_pt_cmd *xpt_cmd)
{
        struct se_cmd *se_cmd = &xpt_cmd->se_cmd;
        sense_reason_t sense_rc;

        sense_rc = transport_generic_new_cmd(se_cmd);
        if (sense_rc)
                return -EINVAL;

        if (se_cmd->data_direction == DMA_TO_DEVICE)
                target_execute_cmd(se_cmd);

        wait_for_completion_interruptible(&xpt_cmd->xpt_passthrough_sem);

        pr_debug("target_xcopy_issue_pt_cmd(): SCSI status: 0x%02x\n",
                        se_cmd->scsi_status);

        return (se_cmd->scsi_status) ? -EINVAL : 0;
}

static int target_xcopy_read_source(
        struct se_cmd *ec_cmd,
        struct xcopy_op *xop,
        struct se_device *src_dev,
        sector_t src_lba,
        u32 src_bytes)
{
        struct xcopy_pt_cmd xpt_cmd;
        struct se_cmd *se_cmd = &xpt_cmd.se_cmd;
        u32 transfer_length_block = src_bytes / src_dev->dev_attrib.block_size;
        int rc;
        unsigned char cdb[16];
        bool remote_port = (xop->op_origin == XCOL_DEST_RECV_OP);

        memset(&xpt_cmd, 0, sizeof(xpt_cmd));
        init_completion(&xpt_cmd.xpt_passthrough_sem);

        memset(&cdb[0], 0, 16);
        cdb[0] = READ_16;
        put_unaligned_be64(src_lba, &cdb[2]);
        put_unaligned_be32(transfer_length_block, &cdb[10]);
        pr_debug("XCOPY: Built READ_16: LBA: %llu Blocks: %u Length: %u\n",
                (unsigned long long)src_lba, transfer_length_block, src_bytes);

        __target_init_cmd(se_cmd, &xcopy_pt_tfo, &xcopy_pt_sess, src_bytes,
                          DMA_FROM_DEVICE, 0, &xpt_cmd.sense_buffer[0], 0,
                          NULL);
        rc = target_xcopy_setup_pt_cmd(&xpt_cmd, xop, src_dev, &cdb[0],
                                remote_port);
        if (rc < 0) {
                ec_cmd->scsi_status = se_cmd->scsi_status;
                goto out;
        }

        pr_debug("XCOPY-READ: Saved xop->xop_data_sg: %p, num: %u for READ"
                " memory\n", xop->xop_data_sg, xop->xop_data_nents);

        rc = target_xcopy_issue_pt_cmd(&xpt_cmd);
        if (rc < 0)
                ec_cmd->scsi_status = se_cmd->scsi_status;
out:
        transport_generic_free_cmd(se_cmd, 0);
        return rc;
}

static int target_xcopy_write_destination(
        struct se_cmd *ec_cmd,
        struct xcopy_op *xop,
        struct se_device *dst_dev,
        sector_t dst_lba,
        u32 dst_bytes)
{
        struct xcopy_pt_cmd xpt_cmd;
        struct se_cmd *se_cmd = &xpt_cmd.se_cmd;
        u32 transfer_length_block = dst_bytes / dst_dev->dev_attrib.block_size;
        int rc;
        unsigned char cdb[16];
        bool remote_port = (xop->op_origin == XCOL_SOURCE_RECV_OP);

        memset(&xpt_cmd, 0, sizeof(xpt_cmd));
        init_completion(&xpt_cmd.xpt_passthrough_sem);

        memset(&cdb[0], 0, 16);
        cdb[0] = WRITE_16;
        put_unaligned_be64(dst_lba, &cdb[2]);
        put_unaligned_be32(transfer_length_block, &cdb[10]);
        pr_debug("XCOPY: Built WRITE_16: LBA: %llu Blocks: %u Length: %u\n",
                (unsigned long long)dst_lba, transfer_length_block, dst_bytes);

        __target_init_cmd(se_cmd, &xcopy_pt_tfo, &xcopy_pt_sess, dst_bytes,
                          DMA_TO_DEVICE, 0, &xpt_cmd.sense_buffer[0], 0,
                          NULL);
        rc = target_xcopy_setup_pt_cmd(&xpt_cmd, xop, dst_dev, &cdb[0],
                                remote_port);
        if (rc < 0) {
                ec_cmd->scsi_status = se_cmd->scsi_status;
                goto out;
        }

        rc = target_xcopy_issue_pt_cmd(&xpt_cmd);
        if (rc < 0)
                ec_cmd->scsi_status = se_cmd->scsi_status;
out:
        transport_generic_free_cmd(se_cmd, 0);
        return rc;
}

static void target_xcopy_do_work(struct work_struct *work)
{
        struct xcopy_op *xop = container_of(work, struct xcopy_op, xop_work);
        struct se_cmd *ec_cmd = xop->xop_se_cmd;
        struct se_device *src_dev, *dst_dev;
        sector_t src_lba, dst_lba, end_lba;
        unsigned long long max_bytes, max_bytes_src, max_bytes_dst, max_blocks;
        int rc = 0;
        unsigned short nolb;
        unsigned int copied_bytes = 0;
        sense_reason_t sense_rc;

        sense_rc = target_parse_xcopy_cmd(xop);
        if (sense_rc != TCM_NO_SENSE)
                goto err_free;

        if (WARN_ON_ONCE(!xop->src_dev) || WARN_ON_ONCE(!xop->dst_dev)) {
                sense_rc = TCM_INVALID_PARAMETER_LIST;
                goto err_free;
        }

        src_dev = xop->src_dev;
        dst_dev = xop->dst_dev;
        src_lba = xop->src_lba;
        dst_lba = xop->dst_lba;
        nolb = xop->nolb;
        end_lba = src_lba + nolb;
        /*
         * Break up XCOPY I/O into hw_max_sectors * hw_block_size sized
         * I/O based on the smallest max_bytes between src_dev + dst_dev
         */
        max_bytes_src = (unsigned long long) src_dev->dev_attrib.hw_max_sectors *
                        src_dev->dev_attrib.hw_block_size;
        max_bytes_dst = (unsigned long long) dst_dev->dev_attrib.hw_max_sectors *
                        dst_dev->dev_attrib.hw_block_size;

        max_bytes = min_t(u64, max_bytes_src, max_bytes_dst);
        max_bytes = min_t(u64, max_bytes, XCOPY_MAX_BYTES);

        /*
         * Using shift instead of the division because otherwise GCC
         * generates __udivdi3 that is missing on i386
         */
        max_blocks = max_bytes >> ilog2(src_dev->dev_attrib.block_size);

        pr_debug("%s: nolb: %u, max_blocks: %llu end_lba: %llu\n", __func__,
                        nolb, max_blocks, (unsigned long long)end_lba);
        pr_debug("%s: Starting src_lba: %llu, dst_lba: %llu\n", __func__,
                        (unsigned long long)src_lba, (unsigned long long)dst_lba);

        while (nolb) {
                u32 cur_bytes = min_t(u64, max_bytes, nolb * src_dev->dev_attrib.block_size);
                unsigned short cur_nolb = cur_bytes / src_dev->dev_attrib.block_size;

                if (cur_bytes != xop->xop_data_bytes) {
                        /*
                         * (Re)allocate a buffer large enough to hold the XCOPY
                         * I/O size, which can be reused each read / write loop.
                         */
                        target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);
                        rc = target_alloc_sgl(&xop->xop_data_sg,
                                              &xop->xop_data_nents,
                                              cur_bytes,
                                              false, false);
                        if (rc < 0)
                                goto out;
                        xop->xop_data_bytes = cur_bytes;
                }

                pr_debug("%s: Calling read src_dev: %p src_lba: %llu, cur_nolb: %hu\n",
                                __func__, src_dev, (unsigned long long)src_lba, cur_nolb);

                rc = target_xcopy_read_source(ec_cmd, xop, src_dev, src_lba, cur_bytes);
                if (rc < 0)
                        goto out;

                src_lba += cur_bytes / src_dev->dev_attrib.block_size;
                pr_debug("%s: Incremented READ src_lba to %llu\n", __func__,
                                (unsigned long long)src_lba);

                pr_debug("%s: Calling write dst_dev: %p dst_lba: %llu, cur_nolb: %u\n",
                                __func__, dst_dev, (unsigned long long)dst_lba, cur_nolb);

                rc = target_xcopy_write_destination(ec_cmd, xop, dst_dev,
                                                dst_lba, cur_bytes);
                if (rc < 0)
                        goto out;

                dst_lba += cur_bytes / dst_dev->dev_attrib.block_size;
                pr_debug("%s: Incremented WRITE dst_lba to %llu\n", __func__,
                                (unsigned long long)dst_lba);

                copied_bytes += cur_bytes;
                nolb -= cur_bytes / src_dev->dev_attrib.block_size;
        }

        xcopy_pt_undepend_remotedev(xop);
        target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);
        kfree(xop);

        pr_debug("%s: Final src_lba: %llu, dst_lba: %llu\n", __func__,
                (unsigned long long)src_lba, (unsigned long long)dst_lba);
        pr_debug("%s: Blocks copied: %u, Bytes Copied: %u\n", __func__,
                copied_bytes / dst_dev->dev_attrib.block_size, copied_bytes);

        pr_debug("%s: Setting X-COPY GOOD status -> sending response\n", __func__);
        target_complete_cmd(ec_cmd, SAM_STAT_GOOD);
        return;

out:
        /*
         * The XCOPY command was aborted after some data was transferred.
         * Terminate command with CHECK CONDITION status, with the sense key
         * set to COPY ABORTED.
         */
        sense_rc = TCM_COPY_TARGET_DEVICE_NOT_REACHABLE;
        xcopy_pt_undepend_remotedev(xop);
        target_free_sgl(xop->xop_data_sg, xop->xop_data_nents);

err_free:
        kfree(xop);
        pr_warn_ratelimited("%s: rc: %d, sense: %u, XCOPY operation failed\n",
                           __func__, rc, sense_rc);
        target_complete_cmd_with_sense(ec_cmd, SAM_STAT_CHECK_CONDITION, sense_rc);
}

/*
 * Returns TCM_NO_SENSE upon success or a sense code != TCM_NO_SENSE if parsing
 * fails.
 */
static sense_reason_t target_parse_xcopy_cmd(struct xcopy_op *xop)
{
        struct se_cmd *se_cmd = xop->xop_se_cmd;
        unsigned char *p = NULL, *seg_desc;
        unsigned int list_id, list_id_usage, sdll, inline_dl;
        sense_reason_t ret = TCM_INVALID_PARAMETER_LIST;
        int rc;
        unsigned short tdll;

        p = transport_kmap_data_sg(se_cmd);
        if (!p) {
                pr_err("transport_kmap_data_sg() failed in target_do_xcopy\n");
                return TCM_OUT_OF_RESOURCES;
        }

        list_id = p[0];
        list_id_usage = (p[1] & 0x18) >> 3;

        /*
         * Determine TARGET DESCRIPTOR LIST LENGTH + SEGMENT DESCRIPTOR LIST LENGTH
         */
        tdll = get_unaligned_be16(&p[2]);
        sdll = get_unaligned_be32(&p[8]);
        if (tdll + sdll > RCR_OP_MAX_DESC_LIST_LEN) {
                pr_err("XCOPY descriptor list length %u exceeds maximum %u\n",
                       tdll + sdll, RCR_OP_MAX_DESC_LIST_LEN);
                ret = TCM_PARAMETER_LIST_LENGTH_ERROR;
                goto out;
        }

        inline_dl = get_unaligned_be32(&p[12]);
        if (inline_dl != 0) {
                pr_err("XCOPY with non zero inline data length\n");
                goto out;
        }

        if (se_cmd->data_length < (XCOPY_HDR_LEN + tdll + sdll + inline_dl)) {
                pr_err("XCOPY parameter truncation: data length %u too small "
                        "for tdll: %hu sdll: %u inline_dl: %u\n",
                        se_cmd->data_length, tdll, sdll, inline_dl);
                ret = TCM_PARAMETER_LIST_LENGTH_ERROR;
                goto out;
        }

        pr_debug("Processing XCOPY with list_id: 0x%02x list_id_usage: 0x%02x"
                " tdll: %hu sdll: %u inline_dl: %u\n", list_id, list_id_usage,
                tdll, sdll, inline_dl);

        /*
         * skip over the target descriptors until segment descriptors
         * have been passed - CSCD ids are needed to determine src and dest.
         */
        seg_desc = &p[16] + tdll;

        rc = target_xcopy_parse_segment_descriptors(xop, seg_desc, sdll, &ret);
        if (rc <= 0)
                goto out;

        pr_debug("XCOPY: Processed %d segment descriptors, length: %u\n", rc,
                                rc * XCOPY_SEGMENT_DESC_LEN);

        rc = target_xcopy_parse_target_descriptors(se_cmd, xop, &p[16], tdll, &ret);
        if (rc <= 0)
                goto out;

        if (xop->src_dev->dev_attrib.block_size !=
            xop->dst_dev->dev_attrib.block_size) {
                pr_err("XCOPY: Non matching src_dev block_size: %u + dst_dev"
                       " block_size: %u currently unsupported\n",
                        xop->src_dev->dev_attrib.block_size,
                        xop->dst_dev->dev_attrib.block_size);
                xcopy_pt_undepend_remotedev(xop);
                ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                goto out;
        }

        pr_debug("XCOPY: Processed %d target descriptors, length: %u\n", rc,
                                rc * XCOPY_TARGET_DESC_LEN);
        transport_kunmap_data_sg(se_cmd);
        return TCM_NO_SENSE;

out:
        if (p)
                transport_kunmap_data_sg(se_cmd);
        return ret;
}

sense_reason_t target_do_xcopy(struct se_cmd *se_cmd)
{
        struct se_device *dev = se_cmd->se_dev;
        struct xcopy_op *xop;
        unsigned int sa;

        if (!dev->dev_attrib.emulate_3pc) {
                pr_err("EXTENDED_COPY operation explicitly disabled\n");
                return TCM_UNSUPPORTED_SCSI_OPCODE;
        }

        sa = se_cmd->t_task_cdb[1] & 0x1f;
        if (sa != 0x00) {
                pr_err("EXTENDED_COPY(LID4) not supported\n");
                return TCM_UNSUPPORTED_SCSI_OPCODE;
        }

        if (se_cmd->data_length == 0) {
                target_complete_cmd(se_cmd, SAM_STAT_GOOD);
                return TCM_NO_SENSE;
        }
        if (se_cmd->data_length < XCOPY_HDR_LEN) {
                pr_err("XCOPY parameter truncation: length %u < hdr_len %u\n",
                                se_cmd->data_length, XCOPY_HDR_LEN);
                return TCM_PARAMETER_LIST_LENGTH_ERROR;
        }

        xop = kzalloc_obj(struct xcopy_op);
        if (!xop)
                goto err;
        xop->xop_se_cmd = se_cmd;
        INIT_WORK(&xop->xop_work, target_xcopy_do_work);
        if (WARN_ON_ONCE(!queue_work(xcopy_wq, &xop->xop_work)))
                goto free;
        return TCM_NO_SENSE;

free:
        kfree(xop);

err:
        return TCM_OUT_OF_RESOURCES;
}

static sense_reason_t target_rcr_operating_parameters(struct se_cmd *se_cmd)
{
        unsigned char *p;

        p = transport_kmap_data_sg(se_cmd);
        if (!p) {
                pr_err("transport_kmap_data_sg failed in"
                       " target_rcr_operating_parameters\n");
                return TCM_OUT_OF_RESOURCES;
        }

        if (se_cmd->data_length < 54) {
                pr_err("Receive Copy Results Op Parameters length"
                       " too small: %u\n", se_cmd->data_length);
                transport_kunmap_data_sg(se_cmd);
                return TCM_INVALID_CDB_FIELD;
        }
        /*
         * Set SNLID=1 (Supports no List ID)
         */
        p[4] = 0x1;
        /*
         * MAXIMUM TARGET DESCRIPTOR COUNT
         */
        put_unaligned_be16(RCR_OP_MAX_TARGET_DESC_COUNT, &p[8]);
        /*
         * MAXIMUM SEGMENT DESCRIPTOR COUNT
         */
        put_unaligned_be16(RCR_OP_MAX_SG_DESC_COUNT, &p[10]);
        /*
         * MAXIMUM DESCRIPTOR LIST LENGTH
         */
        put_unaligned_be32(RCR_OP_MAX_DESC_LIST_LEN, &p[12]);
        /*
         * MAXIMUM SEGMENT LENGTH
         */
        put_unaligned_be32(RCR_OP_MAX_SEGMENT_LEN, &p[16]);
        /*
         * MAXIMUM INLINE DATA LENGTH for SA 0x04 (NOT SUPPORTED)
         */
        put_unaligned_be32(0x0, &p[20]);
        /*
         * HELD DATA LIMIT
         */
        put_unaligned_be32(0x0, &p[24]);
        /*
         * MAXIMUM STREAM DEVICE TRANSFER SIZE
         */
        put_unaligned_be32(0x0, &p[28]);
        /*
         * TOTAL CONCURRENT COPIES
         */
        put_unaligned_be16(RCR_OP_TOTAL_CONCURR_COPIES, &p[34]);
        /*
         * MAXIMUM CONCURRENT COPIES
         */
        p[36] = RCR_OP_MAX_CONCURR_COPIES;
        /*
         * DATA SEGMENT GRANULARITY (log 2)
         */
        p[37] = RCR_OP_DATA_SEG_GRAN_LOG2;
        /*
         * INLINE DATA GRANULARITY log 2)
         */
        p[38] = RCR_OP_INLINE_DATA_GRAN_LOG2;
        /*
         * HELD DATA GRANULARITY
         */
        p[39] = RCR_OP_HELD_DATA_GRAN_LOG2;
        /*
         * IMPLEMENTED DESCRIPTOR LIST LENGTH
         */
        p[43] = 0x2;
        /*
         * List of implemented descriptor type codes (ordered)
         */
        p[44] = 0x02; /* Copy Block to Block device */
        p[45] = 0xe4; /* Identification descriptor target descriptor */

        /*
         * AVAILABLE DATA (n-3)
         */
        put_unaligned_be32(42, &p[0]);

        transport_kunmap_data_sg(se_cmd);
        target_complete_cmd(se_cmd, SAM_STAT_GOOD);

        return TCM_NO_SENSE;
}

sense_reason_t target_do_receive_copy_results(struct se_cmd *se_cmd)
{
        unsigned char *cdb = &se_cmd->t_task_cdb[0];
        int sa = (cdb[1] & 0x1f), list_id = cdb[2];
        struct se_device *dev = se_cmd->se_dev;
        sense_reason_t rc = TCM_NO_SENSE;

        if (!dev->dev_attrib.emulate_3pc) {
                pr_debug("Third-party copy operations explicitly disabled\n");
                return TCM_UNSUPPORTED_SCSI_OPCODE;
        }

        pr_debug("Entering target_do_receive_copy_results: SA: 0x%02x, List ID:"
                " 0x%02x, AL: %u\n", sa, list_id, se_cmd->data_length);

        if (list_id != 0) {
                pr_err("Receive Copy Results with non zero list identifier"
                       " not supported\n");
                return TCM_INVALID_CDB_FIELD;
        }

        switch (sa) {
        case RCR_SA_OPERATING_PARAMETERS:
                rc = target_rcr_operating_parameters(se_cmd);
                break;
        case RCR_SA_COPY_STATUS:
        case RCR_SA_RECEIVE_DATA:
        case RCR_SA_FAILED_SEGMENT_DETAILS:
        default:
                pr_err("Unsupported SA for receive copy results: 0x%02x\n", sa);
                return TCM_INVALID_CDB_FIELD;
        }

        return rc;
}