/*
 *  common.c
 *
 *  Copyright (C) 2007 - 2018 Vladislav Bolkhovitin <vst@vlnb.net>
 *  Copyright (C) 2007 - 2018 Western Digital Corporation
 *
 *  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, version 2
 *  of the License.
 *
 *  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 <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <getopt.h>
#include <inttypes.h>

#include <sys/ioctl.h>
#include <poll.h>

#include <arpa/inet.h>

#include <pthread.h>

#include "common.h"

static void exec_inquiry(struct vdisk_cmd *vcmd);
static void exec_request_sense(struct vdisk_cmd *vcmd);
static void exec_mode_sense(struct vdisk_cmd *vcmd);
static void exec_mode_select(struct vdisk_cmd *vcmd);
static void exec_read_capacity(struct vdisk_cmd *vcmd);
static void exec_read_capacity16(struct vdisk_cmd *vcmd);
static void exec_read_toc(struct vdisk_cmd *vcmd);
static void exec_prevent_allow_medium_removal(struct vdisk_cmd *vcmd);
static int exec_fsync(struct vdisk_cmd *vcmd);
static void exec_read(struct vdisk_cmd *vcmd, loff_t loff);
static void exec_write(struct vdisk_cmd *vcmd, loff_t loff);
static void exec_verify(struct vdisk_cmd *vcmd, loff_t loff);
static void exec_write_same(struct vdisk_cmd *vcmd);

static int open_dev_fd(struct vdisk_dev *dev)
{
	int res;
	int open_flags = O_LARGEFILE;

	if (dev->rd_only_flag)
		open_flags |= O_RDONLY;
	else
		open_flags |= O_RDWR;
	if (dev->o_direct_flag)
		open_flags |= O_DIRECT;
	if (dev->wt_flag)
		open_flags |= O_DSYNC;

	TRACE_DBG("Opening file %s, flags 0x%x", dev->file_name, open_flags);
	res = open(dev->file_name, open_flags);

	return res;
}

static void set_resp_data_len(struct vdisk_cmd *vcmd, int32_t resp_data_len)
{
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;

	TRACE_ENTRY();

	if (vcmd->may_need_to_free_pbuf && (resp_data_len == 0)) {
		struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
		free((void *)(unsigned long)cmd->pbuf);
		cmd->pbuf = 0;
		reply->pbuf = 0;
	}

	reply->resp_data_len = resp_data_len;

	TRACE_EXIT();
	return;
}

static inline void set_cmd_error_status(struct vdisk_cmd *vcmd,
	int status)
{
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	reply->status = status;
	set_resp_data_len(vcmd, 0);
	return;
}

static int set_sense(uint8_t *buffer, int len, int key, int asc, int ascq)
{
	int res = 18;

	EXTRACHECKS_BUG_ON(len < res);

	memset(buffer, 0, res);

	buffer[0] = 0x70;	/* Error Code			*/
	buffer[2] = key;	/* Sense Key			*/
	buffer[7] = 0x0a;	/* Additional Sense Length	*/
	buffer[12] = asc;	/* ASC				*/
	buffer[13] = ascq;	/* ASCQ				*/

	TRACE_BUFFER("Sense set", buffer, res);
	return res;
}

/*
 * ToDo: implement analogs of scst_set_invalid_field_in_cdb() and
 * scst_set_invalid_field_in_parm_list()
 */

static void set_cmd_error(struct vdisk_cmd *vcmd, int key, int asc, int ascq)
{
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;

	TRACE_ENTRY();

	EXTRACHECKS_BUG_ON(vcmd->cmd->subcode != SCST_USER_EXEC);

	set_cmd_error_status(vcmd, SAM_STAT_CHECK_CONDITION);
	reply->sense_len = set_sense(vcmd->sense, sizeof(vcmd->sense), key,
		asc, ascq);
	reply->psense_buffer = (unsigned long)vcmd->sense;

	TRACE_EXIT();
	return;
}

static void set_busy(struct vdisk_cmd *vcmd)
{
	TRACE_ENTRY();

	set_cmd_error_status(vcmd, SAM_STAT_TASK_SET_FULL);
	TRACE_MGMT_DBG("%s", "Sending QUEUE_FULL status");

	TRACE_EXIT();
	return;
}

static int do_parse(struct vdisk_cmd *vcmd)
{
	int res = 0;
	struct scst_user_scsi_cmd_parse *cmd = &vcmd->cmd->parse_cmd;
	struct scst_user_scsi_cmd_reply_parse *reply = &vcmd->reply->parse_reply;

	TRACE_ENTRY();

	memset(reply, 0, sizeof(*reply));
	vcmd->reply->cmd_h = vcmd->cmd->cmd_h;
	vcmd->reply->subcode = vcmd->cmd->subcode;

	if (cmd->expected_values_set == 0) {
		PRINT_ERROR("%s", "Oops, expected values are not set");
		reply->bufflen = -1; /* invalid value */
		goto out;
	}

	reply->queue_type = cmd->queue_type;
	reply->data_direction = cmd->expected_data_direction;
	reply->lba = cmd->lba;
	reply->data_len = cmd->expected_transfer_len;
	reply->bufflen = cmd->expected_transfer_len;
	reply->out_bufflen = cmd->expected_out_transfer_len;
	reply->cdb_len = cmd->cdb_len;

	if (cmd->op_flags & SCST_INFO_VALID)
		reply->op_flags = cmd->op_flags;
	else {
		TRACE_DBG("Extra parse (op %x)", cmd->cdb[0]);

		if (reply->data_direction & SCST_DATA_WRITE)
			reply->op_flags |= SCST_WRITE_MEDIUM;
		reply->op_flags |= SCST_INFO_VALID;
	}

out:
	TRACE_EXIT_RES(res);
	return res;
}

static struct vdisk_tgt_dev *find_tgt_dev(struct vdisk_dev *dev, uint64_t sess_h)
{
	unsigned int i;
	struct vdisk_tgt_dev *res = NULL;

	for(i = 0; i < ARRAY_SIZE(dev->tgt_devs); i++) {
		if (dev->tgt_devs[i].sess_h == sess_h) {
			res = &dev->tgt_devs[i];
			break;
		}
	}
	return res;
}

static struct vdisk_tgt_dev *find_empty_tgt_dev(struct vdisk_dev *dev)
{
	unsigned int i;
	struct vdisk_tgt_dev *res = NULL;

	for(i = 0; i < ARRAY_SIZE(dev->tgt_devs); i++) {
		if (dev->tgt_devs[i].sess_h == 0) {
			res = &dev->tgt_devs[i];
			break;
		}
	}
	return res;
}

static int do_exec(struct vdisk_cmd *vcmd)
{
	int res = 0;
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	uint64_t lba_start = cmd->lba;
	int64_t data_len = cmd->data_len;
	uint8_t *cdb = cmd->cdb;
	int opcode = cdb[0];
	loff_t loff;
	int fua = 0;

	TRACE_ENTRY();

	/* Must be reinitialized each time to avoid crash on stale value */
	vcmd->may_need_to_free_pbuf = 0;

	switch(cmd->queue_type) {
	case SCST_CMD_QUEUE_ORDERED:
		TRACE(TRACE_ORDER, "ORDERED cmd_h %d", vcmd->cmd->cmd_h);
		break;
	case SCST_CMD_QUEUE_HEAD_OF_QUEUE:
		TRACE(TRACE_ORDER, "HQ cmd_h %d", vcmd->cmd->cmd_h);
		break;
	default:
		break;
	}

	memset(reply, 0, sizeof(*reply));
	vcmd->reply->cmd_h = vcmd->cmd->cmd_h;
	vcmd->reply->subcode = vcmd->cmd->subcode;
	reply->reply_type = SCST_EXEC_REPLY_COMPLETED;

#ifdef DEBUG_SENSE
	if ((random() % 100000) == 75) {
		set_cmd_error(vcmd, SCST_LOAD_SENSE(scst_sense_internal_failure));
		goto out;
	}
#endif

#ifdef DEBUG_TM_IGNORE
	if (dev->debug_tm_ignore && (random() % 10000) == 75) {
		TRACE_MGMT_DBG("Ignore cmd op %x (h=%d)", cdb[0],
			vcmd->cmd->cmd_h);
		res = 150;
		goto out;
	}
#endif

	if ((cmd->pbuf == 0) && (cmd->alloc_len != 0)) {
#ifdef DEBUG_NOMEM
		if ((random() % 100) == 75)
			cmd->pbuf = 0;
		else
#endif
			cmd->pbuf = (unsigned long)dev->alloc_fn(cmd->alloc_len);
		vcmd->may_need_to_free_pbuf = 1;
		TRACE_MEM("Buf %"PRIx64" alloced, len %d", cmd->pbuf,
			cmd->alloc_len);
		reply->pbuf = cmd->pbuf;
		if (cmd->pbuf == 0) {
			TRACE(TRACE_OUT_OF_MEM, "Unable to allocate buffer "
				"(len %d)", cmd->alloc_len);
#ifndef DEBUG_NOMEM
			set_busy(vcmd);
#endif
			goto out;
		}
	}

	if (cmd->data_direction & SCST_DATA_READ)
		reply->resp_data_len = cmd->bufflen;

	loff = (loff_t)lba_start << dev->block_shift;
	TRACE_DBG("cmd %d, buf %"PRIx64", lba_start %"PRId64", loff %"PRId64
		", data_len %"PRId64, vcmd->cmd->cmd_h, cmd->pbuf, lba_start,
		(uint64_t)loff, data_len);
	if ((loff < 0) || (data_len < 0) || ((loff + data_len) > dev->file_size)) {
	    	PRINT_INFO("Access beyond the end of the device "
			"(%"PRId64" of %"PRId64", len %"PRId64")", (uint64_t)loff,
			(uint64_t)dev->file_size, data_len);
		set_cmd_error(vcmd, SCST_LOAD_SENSE(
				scst_sense_block_out_range_error));
		goto out;
	}

	switch (opcode) {
	case WRITE_10:
	case WRITE_12:
	case WRITE_16:
		fua = (cdb[1] & 0x8);
		if (cdb[1] & 0x8) {
			TRACE(TRACE_ORDER, "FUA(%d): loff=%"PRId64", "
				"data_len=%"PRId64, fua, (uint64_t)loff,
				data_len);
		}
		break;
	}

	switch (opcode) {
	case READ_6:
	case READ_10:
	case READ_12:
	case READ_16:
		exec_read(vcmd, loff);
		break;
	case WRITE_6:
	case WRITE_10:
	case WRITE_12:
	case WRITE_16:
		if (!dev->rd_only_flag) {
			struct vdisk_tgt_dev *tgt_dev;

			tgt_dev = find_tgt_dev(dev, cmd->sess_h);
			if (tgt_dev == NULL) {
				PRINT_ERROR("Session %"PRIx64" not found",
					cmd->sess_h);
				set_cmd_error(vcmd,
				    SCST_LOAD_SENSE(scst_sense_hardw_error));
				goto out;
			}

			exec_write(vcmd, loff);
			/* O_DSYNC flag is used for WT devices */
			if (fua)
				exec_fsync(vcmd);
		} else {
			PRINT_WARNING("Attempt to write to read-only "
				"device %s", dev->name);
			set_cmd_error(vcmd,
		    		SCST_LOAD_SENSE(scst_sense_data_protect));
		}
		break;
	case WRITE_VERIFY:
	case WRITE_VERIFY_12:
	case WRITE_VERIFY_16:
		if (!dev->rd_only_flag) {
			struct vdisk_tgt_dev *tgt_dev;

			tgt_dev = find_tgt_dev(dev, cmd->sess_h);
			if (tgt_dev == NULL) {
				PRINT_ERROR("Session %"PRIx64" not found",
					cmd->sess_h);
				set_cmd_error(vcmd,
				    SCST_LOAD_SENSE(scst_sense_hardw_error));
				goto out;
			}

			exec_write(vcmd, loff);
			/* O_DSYNC flag is used for WT devices */
			if (reply->status == 0)
				exec_verify(vcmd, loff);
		} else {
			PRINT_WARNING("Attempt to write to read-only "
				"device %s", dev->name);
			set_cmd_error(vcmd,
				SCST_LOAD_SENSE(scst_sense_data_protect));
		}
		break;
	case SYNCHRONIZE_CACHE:
	case SYNCHRONIZE_CACHE_16:
	{
		int immed = cdb[1] & 0x2;
		if (data_len == 0)
			data_len = dev->file_size -
				((loff_t)lba_start << dev->block_shift);
		TRACE(TRACE_ORDER, "SYNCHRONIZE_CACHE: "
			"loff=%"PRId64", data_len=%"PRId64", immed=%d",
			(uint64_t)loff, data_len, immed);
		if (immed) {
			/* ToDo: backgroung exec */
			exec_fsync(vcmd);
			break;
		} else {
			exec_fsync(vcmd);
			break;
		}
	}
	case VERIFY:
	case VERIFY_12:
	case VERIFY_16:
		exec_verify(vcmd, loff);
		break;
	case MODE_SENSE:
	case MODE_SENSE_10:
		exec_mode_sense(vcmd);
		break;
	case MODE_SELECT:
	case MODE_SELECT_10:
		exec_mode_select(vcmd);
		break;
	case ALLOW_MEDIUM_REMOVAL:
		exec_prevent_allow_medium_removal(vcmd);
		break;
	case READ_TOC:
		exec_read_toc(vcmd);
		break;
	case START_STOP:
		exec_fsync(vcmd/*, 0, dev->file_size*/);
		break;
	case RESERVE_6:
	case RESERVE_10:
	case RELEASE_6:
	case RELEASE_10:
	case TEST_UNIT_READY:
		break;
	case INQUIRY:
		exec_inquiry(vcmd);
		break;
	case REQUEST_SENSE:
		exec_request_sense(vcmd);
		break;
	case READ_CAPACITY:
		exec_read_capacity(vcmd);
		break;
	case WRITE_SAME_10:
	case WRITE_SAME_16:
		exec_write_same(vcmd);
		break;
        case SERVICE_ACTION_IN_16:
		if ((cmd->cdb[1] & 0x1f) == SAI_READ_CAPACITY_16)
			exec_read_capacity16(vcmd);
		else {
			TRACE_DBG("Invalid service action %d for SERVICE "
				"ACTION IN", cmd->cdb[1] & 0x1f);
			set_cmd_error(vcmd,
			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
		}
		break;
	case REPORT_LUNS:
	default:
		TRACE_DBG("Invalid opcode 0x%x", opcode);
		set_cmd_error(vcmd, SCST_LOAD_SENSE(scst_sense_invalid_opcode));
		break;
	}

out:
	TRACE_EXIT();
	return res;
}

static int do_alloc_mem(struct vdisk_cmd *vcmd)
{
	struct scst_user_get_cmd *cmd = vcmd->cmd;
	struct scst_user_reply_cmd *reply = vcmd->reply;
	int res = 0;

	TRACE_ENTRY();

	TRACE_MEM("Alloc mem (cmd %d, sess_h %"PRIx64", cdb_len %d, "
		"alloc_len %d, queue_type %d, data_direction %d)",
		cmd->cmd_h, cmd->alloc_cmd.sess_h,
		cmd->alloc_cmd.cdb_len, cmd->alloc_cmd.alloc_len,
		cmd->alloc_cmd.queue_type, cmd->alloc_cmd.data_direction);

	TRACE_BUFF_FLAG(TRACE_MEMORY, "CDB", cmd->alloc_cmd.cdb,
		cmd->alloc_cmd.cdb_len);

	memset(reply, 0, sizeof(*reply));
	reply->cmd_h = cmd->cmd_h;
	reply->subcode = cmd->subcode;
#ifdef DEBUG_NOMEM
	if ((random() % 100) == 75)
		reply->alloc_reply.pbuf = 0;
	else
#endif
		reply->alloc_reply.pbuf = (unsigned long)vcmd->dev->alloc_fn(
						cmd->alloc_cmd.alloc_len);
	TRACE_MEM("Buf %"PRIx64" alloced, len %d", reply->alloc_reply.pbuf,
		cmd->alloc_cmd.alloc_len);
	if (reply->alloc_reply.pbuf == 0) {
		TRACE(TRACE_OUT_OF_MEM, "Unable to allocate buffer (len %d)",
			cmd->alloc_cmd.alloc_len);
	}

	TRACE_EXIT_RES(res);
	return res;
}

static int do_cached_mem_free(struct vdisk_cmd *vcmd)
{
	struct scst_user_get_cmd *cmd = vcmd->cmd;
	struct scst_user_reply_cmd *reply = vcmd->reply;
	int res = 0;

	TRACE_ENTRY();

	TRACE_MEM("Cached mem free (cmd %x, buf %"PRIx64")", cmd->cmd_h,
		cmd->on_cached_mem_free.pbuf);

	free((void *)(unsigned long)cmd->on_cached_mem_free.pbuf);

	memset(reply, 0, sizeof(*reply));
	reply->cmd_h = cmd->cmd_h;
	reply->subcode = cmd->subcode;

	TRACE_EXIT_RES(res);
	return res;
}

static int do_on_free_cmd(struct vdisk_cmd *vcmd)
{
	struct scst_user_get_cmd *cmd = vcmd->cmd;
	struct scst_user_reply_cmd *reply = vcmd->reply;
	int res = 0;

	TRACE_ENTRY();

	TRACE_DBG("On free cmd (cmd %d, resp_data_len %d, aborted %d, "
		"status %d, delivery_status %d)", cmd->cmd_h,
		cmd->on_free_cmd.resp_data_len, cmd->on_free_cmd.aborted,
		cmd->on_free_cmd.status, cmd->on_free_cmd.delivery_status);

	TRACE_MEM("On free cmd (cmd %d, buf %"PRIx64", buffer_cached %d)",
		cmd->cmd_h, cmd->on_free_cmd.pbuf,
		cmd->on_free_cmd.buffer_cached);

	if (!cmd->on_free_cmd.buffer_cached && (cmd->on_free_cmd.pbuf != 0)) {
		TRACE_MEM("Freeing buf %"PRIx64, cmd->on_free_cmd.pbuf);
		free((void *)(unsigned long)cmd->on_free_cmd.pbuf);
	}

	memset(reply, 0, sizeof(*reply));
	reply->cmd_h = cmd->cmd_h;
	reply->subcode = cmd->subcode;

	TRACE_EXIT_RES(res);
	return res;
}

#ifdef DEBUG_EXT_COPY_REMAP
static int do_ext_copy_remap(struct vdisk_cmd *vcmd)
{
	struct scst_user_get_cmd *cmd = vcmd->cmd;
	struct scst_user_ext_copy_remap *rcmd = &cmd->remap_cmd;
	struct scst_user_reply_cmd *reply = vcmd->reply;
	struct scst_user_ext_copy_reply_remap *rreply = &reply->remap_reply;
	static struct scst_user_ext_copy_data_descr d[1];
	int res = 0;

	TRACE_ENTRY();

	TRACE_DBG("Ext copy remap cmd %d", cmd->cmd_h);

	memset(reply, 0, sizeof(*reply));
	reply->cmd_h = cmd->cmd_h;
	reply->subcode = cmd->subcode;

	memset(rreply, 0, sizeof(*rreply));

	/* It's only a debug code, so it's OK to use static descr */

	memset(d, 0, sizeof(d));

	d[0].data_len = rcmd->data_descr.data_len;
	d[0].src_lba = rcmd->data_descr.src_lba;
	d[0].dst_lba = rcmd->data_descr.dst_lba;

#if 1
	rreply->remap_descriptors = (unsigned long)d;
	rreply->remap_descriptors_len = sizeof(d);
#else
	rreply->status = SAM_STAT_CHECK_CONDITION;
	rreply->sense_len = set_sense(vcmd->sense, sizeof(vcmd->sense),
		SCST_LOAD_SENSE(scst_sense_data_protect));
	rreply->psense_buffer = (unsigned long)vcmd->sense;
#endif

	TRACE_EXIT_RES(res);
	return res;
}
#endif

static int do_tm(struct vdisk_cmd *vcmd, int done)
{
	struct scst_user_get_cmd *cmd = vcmd->cmd;
	struct scst_user_reply_cmd *reply = vcmd->reply;
	struct vdisk_dev *dev = vcmd->dev;
	int res = 0;

	TRACE_ENTRY();

	if (cmd->tm_cmd.fn <= SCST_TARGET_RESET)
		TRACE(TRACE_MGMT, "%s TM fn %d (sess_h %"PRIx64", "
			"cmd_h_to_abort %d)", done ? "Done" : "Received",
			cmd->tm_cmd.fn, cmd->tm_cmd.sess_h,
			cmd->tm_cmd.cmd_h_to_abort);
	else
		TRACE_MGMT_DBG("%s TM fn %d (sess_h %"PRIx64", "
			"cmd_h_to_abort %d)", done ? "Done" : "Received",
			cmd->tm_cmd.fn, cmd->tm_cmd.sess_h,
			cmd->tm_cmd.cmd_h_to_abort);

	if (done) {
		switch (cmd->tm_cmd.fn) {
		case SCST_LUN_RESET:
		case SCST_TARGET_RESET:
		case SCST_PR_ABORT_ALL:
			pthread_mutex_lock(&dev->dev_mutex);
			dev->prevent_allow_medium_removal = 0;
			pthread_mutex_unlock(&dev->dev_mutex);
			break;
		}
	}

	memset(reply, 0, sizeof(*reply));
	reply->cmd_h = cmd->cmd_h;
	reply->subcode = cmd->subcode;
	reply->result = 0;

	TRACE_EXIT_RES(res);
	return res;
}

static int do_sess(struct vdisk_cmd *vcmd)
{
	struct scst_user_get_cmd *cmd = vcmd->cmd;
	struct scst_user_reply_cmd *reply = vcmd->reply;
	int res = 0;
	struct vdisk_tgt_dev *tgt_dev;

	TRACE_ENTRY();

	/*
	 * We are guaranteed to have one and only one command at this point,
	 * which is ATTACH_SESS/DETACH_SESS, so no protection is needed
	 */

	tgt_dev = find_tgt_dev(vcmd->dev, cmd->sess.sess_h);

	if (cmd->subcode == SCST_USER_ATTACH_SESS) {
		if (tgt_dev != NULL) {
			PRINT_ERROR("Session %"PRIx64" already exists)",
				cmd->sess.sess_h);
			res = EEXIST;
			goto reply;
		}

		tgt_dev = find_empty_tgt_dev(vcmd->dev);
		if (tgt_dev == NULL) {
			PRINT_ERROR("Too many initiators, session %"PRIx64
				" refused)", cmd->sess.sess_h);
			res = ENOMEM;
			goto reply;
		}

		tgt_dev->sess_h = cmd->sess.sess_h;

		PRINT_INFO("Session from initiator %s (target %s) attached "
			"(LUN %"PRIx64", threads_num %d, rd_only %d, sess_h "
			"%"PRIx64")", cmd->sess.initiator_name,
			cmd->sess.target_name, cmd->sess.lun,
			cmd->sess.threads_num, cmd->sess.rd_only,
			cmd->sess.sess_h);
	} else {
		if (tgt_dev == NULL) {
			PRINT_ERROR("Session %"PRIx64" not found)",
				cmd->sess.sess_h);
			res = ESRCH;
			goto reply;
		}
		tgt_dev->sess_h = 0;
		PRINT_INFO("Session detached (sess_h %"PRIx64")",
			cmd->sess.sess_h);
	}

reply:
	memset(reply, 0, sizeof(*reply));
	reply->cmd_h = cmd->cmd_h;
	reply->subcode = cmd->subcode;
	reply->result = res;

	TRACE_EXIT_RES(res);
	return res;
}

static int process_cmd(struct vdisk_cmd *vcmd)
{
	struct scst_user_get_cmd *cmd = vcmd->cmd;
	struct scst_user_reply_cmd *reply = vcmd->reply;
	int res = 0;

	TRACE_ENTRY();

	TRACE_BUFFER("Received cmd", cmd, sizeof(*cmd));

	switch(cmd->subcode) {
	case SCST_USER_EXEC:
		if (cmd->exec_cmd.data_direction & SCST_DATA_WRITE) {
			TRACE_BUFFER("Received cmd data",
				(void *)(unsigned long)cmd->exec_cmd.pbuf,
				cmd->exec_cmd.bufflen);
		}
		res = do_exec(vcmd);
		if ((reply->exec_reply.resp_data_len != 0) && (res != 150)) {
			TRACE_BUFFER("Reply data",
				(void *)(unsigned long)reply->exec_reply.pbuf,
				reply->exec_reply.resp_data_len);
		}
		break;

	case SCST_USER_ALLOC_MEM:
		res = do_alloc_mem(vcmd);
		break;

	case SCST_USER_PARSE:
		res = do_parse(vcmd);
		break;

	case SCST_USER_ON_CACHED_MEM_FREE:
		res = do_cached_mem_free(vcmd);
		break;

	case SCST_USER_ON_FREE_CMD:
		res = do_on_free_cmd(vcmd);
		break;

#ifdef DEBUG_EXT_COPY_REMAP
		case SCST_USER_EXT_COPY_REMAP:
			res = do_ext_copy_remap(vcmd);
			break;
#endif

	case SCST_USER_TASK_MGMT_RECEIVED:
		res = do_tm(vcmd, 0);
		break;

	case SCST_USER_TASK_MGMT_DONE:
		res = do_tm(vcmd, 1);
#ifdef DEBUG_TM_FN_IGNORE
		if (dev->debug_tm_ignore) {
			sleep(15);
		}
#endif
		break;

	case SCST_USER_ATTACH_SESS:
	case SCST_USER_DETACH_SESS:
		res = do_sess(vcmd);
		break;

	default:
		PRINT_ERROR("Unknown or wrong cmd subcode %x",
			cmd->subcode);
		res = -EINVAL;
		goto out;
	}

out:
	TRACE_EXIT_RES(res);
	return res;
}

void *main_loop(void *arg)
{
	int res = 0, i, j;
	struct vdisk_dev *dev = (struct vdisk_dev *)arg;
	struct scst_user_get_cmd cmd;
	struct scst_user_reply_cmd reply;
	struct vdisk_cmd vcmd = {
		.fd = -1,
		.cmd = &cmd,
		.dev = dev,
		.may_need_to_free_pbuf = 0,
		.reply = &reply,
		.sense = {0}
	};
	int scst_usr_fd = dev->scst_usr_fd;
	struct pollfd pl;
#define MULTI_CMDS_CNT 2
	struct {
		struct scst_user_reply_cmd replies[MULTI_CMDS_CNT];
		struct scst_user_get_multi multi_cmd;
		struct scst_user_get_cmd cmds[MULTI_CMDS_CNT];
	} multi;

	memset(&multi, 0, sizeof(multi));

	TRACE_ENTRY();

	vcmd.fd = open_dev_fd(dev);
	if (vcmd.fd < 0) {
		res = -errno;
		PRINT_ERROR("Unable to open file %s (%s)", dev->file_name,
			strerror(-res));
		goto out;
	}

	memset(&pl, 0, sizeof(pl));
	pl.fd = scst_usr_fd;
	pl.events = POLLIN;

	cmd.preply = 0;
	multi.multi_cmd.preplies = (uintptr_t)&multi.replies[0];
	multi.multi_cmd.replies_cnt = 0;
	multi.multi_cmd.cmds_cnt = MULTI_CMDS_CNT;

	while(1) {
#ifdef DEBUG_TM_IGNORE_ALL
		if (dev->debug_tm_ignore && (random() % 50000) == 55) {
			TRACE_MGMT_DBG("%s", "Ignore ALL");
			dev->debug_tm_ignore_all = 1;
		}
		if (dev->debug_tm_ignore_all) {
			/* Go Astral */
			while(1) {
				sleep(60);
			}
		}
#endif

		if (use_multi) {
			TRACE_DBG("preplies %p (first: %p), replies_cnt %d, "
				"replies_done %d, cmds_cnt %d", (void *)(uintptr_t)multi.multi_cmd.preplies,
				&multi.replies[0], multi.multi_cmd.replies_cnt,
				multi.multi_cmd.replies_done, multi.multi_cmd.cmds_cnt);
			res = ioctl(scst_usr_fd, SCST_USER_REPLY_AND_GET_MULTI, &multi.multi_cmd);
		} else
			res = ioctl(scst_usr_fd, SCST_USER_REPLY_AND_GET_CMD, &cmd);
		if (res != 0) {
			res = errno;
			switch(res) {
			case ESRCH:
			case EBUSY:
				TRACE_MGMT_DBG("SCST_USER returned %d (%s)", res, strerror(res));
				cmd.preply = 0;
				multi.multi_cmd.preplies = (uintptr_t)&multi.replies[0];
				multi.multi_cmd.replies_cnt = 0;
				multi.multi_cmd.cmds_cnt = MULTI_CMDS_CNT;
				/* fall through */
			case EINTR:
				continue;
			case EAGAIN:
				TRACE_DBG("SCST_USER returned EAGAIN (%d)", res);
				cmd.preply = 0;
				multi.multi_cmd.preplies = (uintptr_t)&multi.replies[0];
				multi.multi_cmd.replies_cnt = 0;
				multi.multi_cmd.cmds_cnt = MULTI_CMDS_CNT;
				if (dev->non_blocking)
					break;
				else
					continue;
			default:
				PRINT_ERROR("SCST_USER failed: %s (%d)", strerror(res), res);
#if 1
				cmd.preply = 0;
				multi.multi_cmd.preplies = (uintptr_t)&multi.replies[0];
				multi.multi_cmd.replies_cnt = 0;
				multi.multi_cmd.cmds_cnt = MULTI_CMDS_CNT;
				continue;
#else
				goto out_close;
#endif
			}
again_poll:
			res = poll(&pl, 1, -1);
			if (res > 0)
				continue;
			else if (res == 0)
				goto again_poll;
			else {
				res = errno;
				switch(res) {
				case ESRCH:
				case EBUSY:
				case EAGAIN:
					TRACE_MGMT_DBG("poll() returned %d "
						"(%s)", res, strerror(res));
				case EINTR:
					goto again_poll;
				default:
					PRINT_ERROR("poll() failed: %s", strerror(res));
#if 1
					goto again_poll;
#else
					goto out_close;
#endif
				}
			}
		}

		if (use_multi) {
			if (multi.multi_cmd.replies_done < multi.multi_cmd.replies_cnt) {
				TRACE_MGMT_DBG("replies_done %d < replies_cnt %d (dev %s)",
					multi.multi_cmd.replies_done, multi.multi_cmd.replies_cnt, dev->name);
				multi.multi_cmd.preplies = (uintptr_t)&multi.replies[multi.multi_cmd.replies_done];
				multi.multi_cmd.replies_cnt = multi.multi_cmd.replies_cnt - multi.multi_cmd.replies_done;
				multi.multi_cmd.cmds_cnt = MULTI_CMDS_CNT;
				continue;
			}
			TRACE_DBG("cmds_cnt %d", multi.multi_cmd.cmds_cnt);
			multi.multi_cmd.preplies = (uintptr_t)&multi.replies[0];
			for (i = 0, j = 0; i < multi.multi_cmd.cmds_cnt; i++, j++) {
				vcmd.cmd = &multi.cmds[i];
				vcmd.reply = &multi.replies[j];
				res = process_cmd(&vcmd);
#ifdef DEBUG_TM_IGNORE
				if (res == 150) {
					j--;
					continue;
				}
#endif
				if (res != 0)
					goto out_close;
				TRACE_BUFFER("Sending reply", vcmd.reply, sizeof(reply));
			}
			multi.multi_cmd.replies_cnt = j;
			multi.multi_cmd.cmds_cnt = MULTI_CMDS_CNT;
		} else {
			res = process_cmd(&vcmd);
#ifdef DEBUG_TM_IGNORE
			if (res == 150) {
				cmd.preply = 0;
				continue;
			}
#endif
			if (res != 0)
				goto out_close;

			cmd.preply = (unsigned long)&reply;
			TRACE_BUFFER("Sending reply", &reply, sizeof(reply));
		}
	}

out_close:
	close(vcmd.fd);

out:
	PRINT_INFO("Thread %d exiting (res=%d)", gettid(), res);

	TRACE_EXIT_RES(res);
	return (void *)(long)res;
}

uint64_t gen_dev_id_num(const struct vdisk_dev *dev)
{
	uint32_t dev_id_num;

	dev_id_num = crc32buf(dev->name, strlen(dev->name)+1);

	return ((uint64_t)vdisk_ID << 32) | dev_id_num;
}

static void exec_inquiry(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	int resp_len = 0;
	int length = cmd->bufflen;
	unsigned int i;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	uint8_t buf[INQ_BUF_SZ];

	TRACE_ENTRY();

	if (cmd->cdb[1] & CMDDT) {
		TRACE_DBG("%s", "INQUIRY: CMDDT is unsupported");
		set_cmd_error(vcmd,
		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
		goto out;
	}

	memset(buf, 0, sizeof(buf));
	buf[0] = dev->type;      /* type dev */
	if (buf[0] == TYPE_ROM)
		buf[1] = 0x80;      /* removable */
	/* Vital Product */
	if (cmd->cdb[1] & EVPD) {
		uint64_t dev_id_num = gen_dev_id_num(dev);

		if (0 == cmd->cdb[2]) { /* supported vital product data pages */
			buf[3] = 5;
			buf[4] = 0x0; /* this page */
			buf[5] = 0x80; /* unit serial number */
			buf[6] = 0x83; /* device identification */
			buf[7] = 0xB0; /* block limits */
			buf[8] = 0xB1; /* block device characteristics */
			resp_len = buf[3] + 6;
		} else if (0x80 == cmd->cdb[2]) { /* unit serial number */
			unsigned int usn_len = strlen(dev->usn);

			buf[1] = 0x80;
			buf[3] = usn_len;
			assert(4 + usn_len <= sizeof(buf));
			memcpy(&buf[4], dev->usn, usn_len);
			resp_len = buf[3] + 4;
		} else if (0x83 == cmd->cdb[2]) { /* device identification */
			int num = 4;
			char *t10_id = (char *)&buf[num + 12];

			buf[1] = 0x83;
			/* Two identification descriptors: */
			/* T10 vendor identifier field format (faked) */
			buf[num + 0] = 0x2;	/* ASCII */
			buf[num + 1] = 0x1;	/* Vendor ID */
			memcpy(&buf[num + 4], VENDOR, 8);
			snprintf(t10_id, sizeof(buf) - num - 12,
				"%"PRIx64"-%s", dev_id_num, dev->name);
			i = strlen(t10_id) + 1;
			TRACE_DBG("t10_dev_id %s", t10_id);
			buf[num + 3] = 8 + i;
			num += buf[num + 3];

#if 0 /* This isn't required and can be misleading, so let's disable it */
			num += 4;

			/* NAA IEEE registered identifier (faked) */
			buf[num] = 0x1;	/* binary */
			buf[num + 1] = 0x3;
			buf[num + 2] = 0x0;
			buf[num + 3] = 0x8;
			buf[num + 4] = 0x51;	/* ieee company id=0x123456 (faked) */
			buf[num + 5] = 0x23;
			buf[num + 6] = 0x45;
			buf[num + 7] = 0x60;
			buf[num + 8] = (dev_id_num >> 24);
			buf[num + 9] = (dev_id_num >> 16) & 0xff;
			buf[num + 10] = (dev_id_num >> 8) & 0xff;
			buf[num + 11] = dev_id_num & 0xff;
			num = num + 12 - 4;
#endif

			resp_len = num;
			buf[2] = (resp_len >> 8) & 0xFF;
			buf[3] = resp_len & 0xFF;
			resp_len += 4;
		} else if (0xB0 == cmd->cdb[2]) {
			/* Block Limits */
			int max_transfer;
			buf[1] = 0xB0;
			buf[3] = 0x3C;
			buf[5] = 0xFF; /* No MAXIMUM COMPARE AND WRITE LENGTH limit */
			/* Optimal transfer granuality is PAGE_SIZE */
			max_transfer = max((int)(4096/dev->block_size), (int)1);
			buf[6] = (max_transfer >> 8) & 0xff;
			buf[7] = max_transfer & 0xff;
			/*
			 * Max transfer len is min of sg limit and 8M, but we
			 * don't have access to them here, so let's use 1M.
			 */
			max_transfer = 1*1024*1024;
			buf[8] = (max_transfer >> 24) & 0xff;
			buf[9] = (max_transfer >> 16) & 0xff;
			buf[10] = (max_transfer >> 8) & 0xff;
			buf[11] = max_transfer & 0xff;
			/*
			 * Let's have optimal transfer len 512KB. Better to not
			 * set it at all, because we don't have such limit,
			 * but some initiators may not understand that (?).
			 * From other side, too big transfers  are not optimal,
			 * because SGV cache supports only <4M buffers.
			 */
			max_transfer = min((int)max_transfer, (int)(512*1024 / dev->block_size));
			buf[12] = (max_transfer >> 24) & 0xff;
			buf[13] = (max_transfer >> 16) & 0xff;
			buf[14] = (max_transfer >> 8) & 0xff;
			buf[15] = max_transfer & 0xff;
			resp_len = buf[3] + 4;
		} else if (0xB1 == cmd->cdb[2]) {
			int r;
			/* Block Device Characteristics */
			buf[1] = 0xB1;
			buf[3] = 0x3C;
#if 0
			if (virt_dev->rotational) {
#endif
				/* 15K RPM */
				r = 0x3A98;
#if 0
			} else
				r = 1;
#endif
			buf[4] = (r >> 8) & 0xff;
			buf[5] = r & 0xff;
			resp_len = buf[3] + 4;
		} else {
			TRACE_DBG("INQUIRY: Unsupported EVPD page %x",
				cmd->cdb[2]);
			set_cmd_error(vcmd,
			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
			goto out;
		}
	} else {
		int len;

		if (cmd->cdb[2] != 0) {
			TRACE_DBG("INQUIRY: Unsupported page %x", cmd->cdb[2]);
			set_cmd_error(vcmd,
			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
			goto out;
		}

		buf[2] = 6;	/* Device complies to SPC-4 */
		buf[3] = 0x12;	/* HiSup + data in format specified in SPC */
		buf[4] = 31;/* n - 4 = 35 - 4 = 31 for full 36 byte data */
		buf[6] = 1; /* MultiP 1 */
		buf[7] = 2; /* CMDQUE 1, BQue 0 => commands queuing supported */

		/* 8 byte ASCII Vendor Identification of the target - left aligned */
		memcpy(&buf[8], VENDOR, 8);

		/* 16 byte ASCII Product Identification of the target - left aligned */
		memset(&buf[16], ' ', 16);
		len = min(strlen(dev->name), (size_t)16);
		memcpy(&buf[16], dev->name, len);

		/* 4 byte ASCII Product Revision Level of the target - left aligned */
		memcpy(&buf[32], FIO_REV, 4);
		resp_len = buf[4] + 5;
	}

	sBUG_ON(resp_len >= (int)sizeof(buf));
	if (length > resp_len)
		length = resp_len;

	memcpy(address, buf, length);

	if (length < reply->resp_data_len)
		set_resp_data_len(vcmd, length);

out:
	TRACE_EXIT();
	return;
}

static void exec_request_sense(struct vdisk_cmd *vcmd)
{
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	int length = cmd->bufflen, l;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	uint8_t b[SCST_STANDARD_SENSE_LEN];

	TRACE_ENTRY();

	l = set_sense(b, sizeof(b), SCST_LOAD_SENSE(scst_sense_no_sense));

	length = min(l, length);

	memcpy(address, b, length);

	if (length < reply->resp_data_len)
		set_resp_data_len(vcmd, length);

	TRACE_EXIT();
	return;
}

/*
 * <<Following mode pages info copied from ST318451LW with some corrections>>
 *
 * ToDo: revise them
 */

static int err_recov_pg(unsigned char *p, int pcontrol)
{	/* Read-Write Error Recovery page for mode_sense */
	const unsigned char err_recov_pg[] = {0x1, 0xa, 0xc0, 11, 240, 0, 0, 0,
					      5, 0, 0xff, 0xff};

	memcpy(p, err_recov_pg, sizeof(err_recov_pg));
	if (1 == pcontrol)
		memset(p + 2, 0, sizeof(err_recov_pg) - 2);
	return sizeof(err_recov_pg);
}

static int disconnect_pg(unsigned char *p, int pcontrol)
{ 	/* Disconnect-Reconnect page for mode_sense */
	const unsigned char disconnect_pg[] = {0x2, 0xe, 128, 128, 0, 10, 0, 0,
					       0, 0, 0, 0, 0, 0, 0, 0};

	memcpy(p, disconnect_pg, sizeof(disconnect_pg));
	if (1 == pcontrol)
		memset(p + 2, 0, sizeof(disconnect_pg) - 2);
	return sizeof(disconnect_pg);
}

static int rigid_geo_pg(unsigned char *p, int pcontrol,
	struct vdisk_dev *dev)
{
	unsigned char geo_m_pg[] = {0x04, 0x16, 0, 0, 0, DEF_HEADS, 0, 0,
				    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
				    0x3a, 0x98/* 15K RPM */, 0, 0};
	int32_t ncyl, n;

	memcpy(p, geo_m_pg, sizeof(geo_m_pg));
	ncyl = dev->nblocks / (DEF_HEADS * DEF_SECTORS);
	if ((dev->nblocks % (DEF_HEADS * DEF_SECTORS)) != 0)
		ncyl++;
	memcpy(&n, p + 2, sizeof(uint32_t));
	n = n | (htonl(ncyl) >> 8);
	memcpy(p + 2, &n, sizeof(uint32_t));
	if (1 == pcontrol)
		memset(p + 2, 0, sizeof(geo_m_pg) - 2);
	return sizeof(geo_m_pg);
}

static int format_pg(unsigned char *p, int pcontrol,
			     struct vdisk_dev *dev)
{       /* Format device page for mode_sense */
	const unsigned char format_pg[] = {0x3, 0x16, 0, 0, 0, 0, 0, 0,
					   0, 0, 0, 0, 0, 0, 0, 0,
					   0, 0, 0, 0, 0x40, 0, 0, 0};

        memcpy(p, format_pg, sizeof(format_pg));
        p[10] = (DEF_SECTORS >> 8) & 0xff;
        p[11] = DEF_SECTORS & 0xff;
        p[12] = (dev->block_size >> 8) & 0xff;
        p[13] = dev->block_size & 0xff;
        if (1 == pcontrol)
                memset(p + 2, 0, sizeof(format_pg) - 2);
        return sizeof(format_pg);
}

static int caching_pg(unsigned char *p, int pcontrol,
			     struct vdisk_dev *dev)
{ 	/* Caching page for mode_sense */
	const unsigned char caching_pg[] = {0x8, 18, 0x10, 0, 0xff, 0xff, 0, 0,
		0xff, 0xff, 0xff, 0xff, 0x80, 0x14, 0, 0, 0, 0, 0, 0};

	memcpy(p, caching_pg, sizeof(caching_pg));
	p[2] |= !(dev->wt_flag) ? WCE : 0;
	if (1 == pcontrol)
		memset(p + 2, 0, sizeof(caching_pg) - 2);
	return sizeof(caching_pg);
}

static int ctrl_m_pg(unsigned char *p, int pcontrol,
			    struct vdisk_dev *dev)
{ 	/* Control mode page for mode_sense */
	const unsigned char ctrl_m_pg[] = {0xa, 0xa, 0x20, 0, 0, 0x40, 0, 0,
					   0, 0, 0x2, 0x4b};

	memcpy(p, ctrl_m_pg, sizeof(ctrl_m_pg));
	if (!dev->wt_flag && !dev->nv_cache)
		p[3] |= 0x10; /* Enable unrestricted reordering */
	if (1 == pcontrol)
		memset(p + 2, 0, sizeof(ctrl_m_pg) - 2);
	return sizeof(ctrl_m_pg);
}

static int iec_m_pg(unsigned char *p, int pcontrol)
{	/* Informational Exceptions control mode page for mode_sense */
	const unsigned char iec_m_pg[] = {0x1c, 0xa, 0x08, 0, 0, 0, 0, 0,
				          0, 0, 0x0, 0x0};
	memcpy(p, iec_m_pg, sizeof(iec_m_pg));
	if (1 == pcontrol)
		memset(p + 2, 0, sizeof(iec_m_pg) - 2);
	return sizeof(iec_m_pg);
}

static void exec_mode_sense(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	int length = cmd->bufflen;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	uint8_t buf[MSENSE_BUF_SZ];
	int blocksize;
	uint64_t nblocks;
	unsigned char dbd, type;
	int pcontrol, pcode, subpcode;
	unsigned char dev_spec;
	int msense_6, offset = 0, len;
	unsigned char *bp;

	TRACE_ENTRY();

	blocksize = dev->block_size;
	nblocks = dev->nblocks;

	type = dev->type;    /* type dev */
	dbd = cmd->cdb[1] & DBD;
	pcontrol = (cmd->cdb[2] & 0xc0) >> 6;
	pcode = cmd->cdb[2] & 0x3f;
	subpcode = cmd->cdb[3];
	msense_6 = (MODE_SENSE == cmd->cdb[0]);
	dev_spec = (dev->rd_only_flag ? WP : 0) | DPOFUA;

	memset(buf, 0, sizeof(buf));

	if (0x3 == pcontrol) {
		TRACE_DBG("%s", "MODE SENSE: Saving values not supported");
		set_cmd_error(vcmd,
		    SCST_LOAD_SENSE(scst_sense_saving_params_unsup));
		goto out;
	}

	if (msense_6) {
		buf[1] = type;
		buf[2] = dev_spec;
		offset = 4;
	} else {
		buf[2] = type;
		buf[3] = dev_spec;
		offset = 8;
	}

	if (0 != subpcode) { /* TODO: Control Extension page */
		TRACE_DBG("%s", "MODE SENSE: Only subpage 0 is supported");
		set_cmd_error(vcmd,
		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
		goto out;
	}

	if (!dbd) {
		/* Create block descriptor */
		buf[offset - 1] = 0x08;		/* block descriptor length */
		if (nblocks >> 32) {
			buf[offset + 0] = 0xFF;
			buf[offset + 1] = 0xFF;
			buf[offset + 2] = 0xFF;
			buf[offset + 3] = 0xFF;
		} else {
			buf[offset + 0] = (nblocks >> (BYTE * 3)) & 0xFF;/* num blks */
			buf[offset + 1] = (nblocks >> (BYTE * 2)) & 0xFF;
			buf[offset + 2] = (nblocks >> (BYTE * 1)) & 0xFF;
			buf[offset + 3] = (nblocks >> (BYTE * 0)) & 0xFF;
		}
		buf[offset + 4] = 0;			/* density code */
		buf[offset + 5] = (blocksize >> (BYTE * 2)) & 0xFF;/* blklen */
		buf[offset + 6] = (blocksize >> (BYTE * 1)) & 0xFF;
		buf[offset + 7] = (blocksize >> (BYTE * 0)) & 0xFF;

		offset += 8;			/* increment offset */
	}

	bp = buf + offset;

	switch (pcode) {
	case 0x1:	/* Read-Write error recovery page, direct access */
		len = err_recov_pg(bp, pcontrol);
		break;
	case 0x2:	/* Disconnect-Reconnect page, all devices */
		len = disconnect_pg(bp, pcontrol);
		break;
        case 0x3:       /* Format device page, direct access */
                len = format_pg(bp, pcontrol, dev);
                break;
	case 0x4:	/* Rigid disk geometry */
		len = rigid_geo_pg(bp, pcontrol, dev);
		break;
	case 0x8:	/* Caching page, direct access */
		len = caching_pg(bp, pcontrol, dev);
		break;
	case 0xa:	/* Control Mode page, all devices */
		len = ctrl_m_pg(bp, pcontrol, dev);
		break;
	case 0x1c:	/* Informational Exceptions Mode page, all devices */
		len = iec_m_pg(bp, pcontrol);
		break;
	case 0x3f:	/* Read all Mode pages */
		len = err_recov_pg(bp, pcontrol);
		len += disconnect_pg(bp + len, pcontrol);
		len += format_pg(bp + len, pcontrol, dev);
		len += caching_pg(bp + len, pcontrol, dev);
		len += ctrl_m_pg(bp + len, pcontrol, dev);
		len += iec_m_pg(bp + len, pcontrol);
		len += rigid_geo_pg(bp + len, pcontrol, dev);
		break;
	default:
		TRACE_DBG("MODE SENSE: Unsupported page %x", pcode);
		set_cmd_error(vcmd,
		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
		goto out;
	}

	offset += len;

	if (msense_6)
		buf[0] = offset - 1;
	else {
		buf[0] = ((offset - 2) >> 8) & 0xff;
		buf[1] = (offset - 2) & 0xff;
	}

	sBUG_ON(offset >= (int)sizeof(buf));
	if (offset > length)
		offset = length;

	memcpy(address, buf, offset);

	if (offset < reply->resp_data_len)
		set_resp_data_len(vcmd, offset);

out:
	TRACE_EXIT();
	return;
}

static int set_wt(struct vdisk_dev *dev, int wt)
{
	int res = 0;

	TRACE_ENTRY();

	if ((dev->wt_flag == wt) || dev->nullio)
		goto out;

	pthread_mutex_lock(&dev->dev_mutex);
	dev->wt_flag = wt;
	pthread_mutex_unlock(&dev->dev_mutex);

out:
	TRACE_EXIT_RES(res);
	return res;
}

static void exec_mode_select(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	int length = cmd->bufflen;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	int mselect_6, offset;

	TRACE_ENTRY();

	mselect_6 = (MODE_SELECT == cmd->cdb[0]);

	if (!(cmd->cdb[1] & PF) || (cmd->cdb[1] & SP)) {
		PRINT_ERROR("MODE SELECT: PF and/or SP are wrongly set "
			"(cdb[1]=%x)", cmd->cdb[1]);
		set_cmd_error(vcmd,
		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
		goto out;
	}

	if (mselect_6) {
		offset = 4;
	} else {
		offset = 8;
	}

	if (address[offset - 1] == 8) {
		offset += 8;
	} else if (address[offset - 1] != 0) {
		PRINT_ERROR("%s", "MODE SELECT: Wrong parameters list "
			"length");
		set_cmd_error(vcmd,
		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_parm_list));
		goto out;
	}

	while (length > offset + 2) {
		if (address[offset] & PS) {
			PRINT_ERROR("%s", "MODE SELECT: Illegal PS bit");
			set_cmd_error(vcmd, SCST_LOAD_SENSE(
			    	scst_sense_invalid_field_in_parm_list));
			goto out;
		}
		if ((address[offset] & 0x3f) == 0x8) {	/* Caching page */
			if (address[offset + 1] != 18) {
				PRINT_ERROR("%s", "MODE SELECT: Invalid "
					"caching page request");
				set_cmd_error(vcmd, SCST_LOAD_SENSE(
				    	scst_sense_invalid_field_in_parm_list));
				goto out;
			}
			if (set_wt(dev,
			      (address[offset + 2] & WCE) ? 0 : 1) != 0) {
				set_cmd_error(vcmd,
				    SCST_LOAD_SENSE(scst_sense_hardw_error));
				goto out;
			}
			break;
		}
		offset += address[offset + 1];
	}

out:
	TRACE_EXIT();
	return;
}

static void exec_read_capacity(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	int length = cmd->bufflen;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	uint32_t blocksize;
	uint64_t nblocks;
	uint8_t buffer[8];

	TRACE_ENTRY();

	blocksize = dev->block_size;
	nblocks = dev->nblocks;

	/* last block on the dev is (nblocks-1) */
	memset(buffer, 0, sizeof(buffer));
	if (nblocks >> 32) {
		buffer[0] = 0xFF;
		buffer[1] = 0xFF;
		buffer[2] = 0xFF;
		buffer[3] = 0xFF;
	} else {
		buffer[0] = ((nblocks - 1) >> (BYTE * 3)) & 0xFF;
		buffer[1] = ((nblocks - 1) >> (BYTE * 2)) & 0xFF;
		buffer[2] = ((nblocks - 1) >> (BYTE * 1)) & 0xFF;
		buffer[3] = ((nblocks - 1) >> (BYTE * 0)) & 0xFF;
	}
	buffer[4] = (blocksize >> (BYTE * 3)) & 0xFF;
	buffer[5] = (blocksize >> (BYTE * 2)) & 0xFF;
	buffer[6] = (blocksize >> (BYTE * 1)) & 0xFF;
	buffer[7] = (blocksize >> (BYTE * 0)) & 0xFF;

	length = min(length, (int)sizeof(buffer));

	memcpy(address, buffer, length);

	if (length < reply->resp_data_len)
		set_resp_data_len(vcmd, length);

	TRACE_EXIT();
	return;
}

static void exec_read_capacity16(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	int length = cmd->bufflen;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	uint32_t blocksize;
	uint64_t nblocks;
	uint8_t buffer[32];

	TRACE_ENTRY();

	blocksize = dev->block_size;
	nblocks = dev->nblocks - 1;

	memset(buffer, 0, sizeof(buffer));

	buffer[0] = nblocks >> 56;
	buffer[1] = (nblocks >> 48) & 0xFF;
	buffer[2] = (nblocks >> 40) & 0xFF;
	buffer[3] = (nblocks >> 32) & 0xFF;
	buffer[4] = (nblocks >> 24) & 0xFF;
	buffer[5] = (nblocks >> 16) & 0xFF;
	buffer[6] = (nblocks >> 8) & 0xFF;
	buffer[7] = nblocks & 0xFF;

	buffer[8] = (blocksize >> (BYTE * 3)) & 0xFF;
	buffer[9] = (blocksize >> (BYTE * 2)) & 0xFF;
	buffer[10] = (blocksize >> (BYTE * 1)) & 0xFF;
	buffer[11] = (blocksize >> (BYTE * 0)) & 0xFF;

	switch (blocksize) {
	case 512:
		buffer[13] = 3;
		break;
	case 1024:
		buffer[13] = 2;
		break;
	case 2048:
		buffer[13] = 1;
		break;
	case 4096:
	default:
		buffer[13] = 0;
		break;
	}

	length = min(length, (int)sizeof(buffer));

	memcpy(address, buffer, length);

	if (length < reply->resp_data_len)
		set_resp_data_len(vcmd, length);

	TRACE_EXIT();
	return;
}

static void exec_read_toc(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	int32_t off = 0;
	int length = cmd->bufflen;
	uint8_t *address = (uint8_t *)(unsigned long)cmd->pbuf;
	uint32_t nblocks;
	uint8_t buffer[4+8+8] = { 0x00, 0x0a, 0x01, 0x01, 0x00, 0x14,
				  0x01, 0x00, 0x00, 0x00, 0x00, 0x00 };

	TRACE_ENTRY();

	if (dev->type != TYPE_ROM) {
		PRINT_ERROR("%s", "READ TOC for non-CDROM device");
		set_cmd_error(vcmd,
			SCST_LOAD_SENSE(scst_sense_invalid_opcode));
		goto out;
	}

	if (cmd->cdb[2] & 0x0e/*Format*/) {
		PRINT_ERROR("%s", "READ TOC: invalid requested data format");
		set_cmd_error(vcmd,
			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
		goto out;
	}

	if ((cmd->cdb[6] != 0 && (cmd->cdb[2] & 0x01)) ||
	    (cmd->cdb[6] > 1 && cmd->cdb[6] != 0xAA)) {
		PRINT_ERROR("READ TOC: invalid requested track number %x",
			cmd->cdb[6]);
		set_cmd_error(vcmd,
			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
		goto out;
	}

	/* ToDo when you have > 8TB ROM device. */
	nblocks = (uint32_t)dev->nblocks;

	/* Header */
	memset(buffer, 0, sizeof(buffer));
	buffer[2] = 0x01;    /* First Track/Session */
	buffer[3] = 0x01;    /* Last Track/Session */
	off = 4;
	if (cmd->cdb[6] <= 1)
        {
		/* Fistr TOC Track Descriptor */
		buffer[off+1] = 0x14; /* ADDR    0x10 - Q Sub-channel encodes current position data
					 CONTROL 0x04 - Data track, recoreded uninterrupted */
		buffer[off+2] = 0x01; /* Track Number */
		off += 8;
        }
	if (!(cmd->cdb[2] & 0x01))
        {
		/* Lead-out area TOC Track Descriptor */
		buffer[off+1] = 0x14;
		buffer[off+2] = 0xAA;     /* Track Number */
		buffer[off+4] = (nblocks >> (BYTE * 3)) & 0xFF; /* Track Start Address */
		buffer[off+5] = (nblocks >> (BYTE * 2)) & 0xFF;
		buffer[off+6] = (nblocks >> (BYTE * 1)) & 0xFF;
		buffer[off+7] = (nblocks >> (BYTE * 0)) & 0xFF;
		off += 8;
        }

	buffer[1] = off - 2;    /* Data  Length */

	if (off > length)
		off = length;

	memcpy(address, buffer, off);

	if (off < reply->resp_data_len)
		set_resp_data_len(vcmd, off);

out:
	TRACE_EXIT();
	return;
}

static void exec_prevent_allow_medium_removal(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;

	TRACE_DBG("PERSIST/PREVENT 0x%02x", cmd->cdb[4]);

	pthread_mutex_lock(&dev->dev_mutex);
	dev->prevent_allow_medium_removal = cmd->cdb[4] & 0x01 ? 1 : 0;
	pthread_mutex_unlock(&dev->dev_mutex);

	return;
}

static int exec_fsync(struct vdisk_cmd *vcmd)
{
	int res = 0;
	struct vdisk_dev *dev = vcmd->dev;

	/* Hopefully, the compiler will generate the single comparison */
	if (dev->nv_cache || dev->wt_flag || dev->rd_only_flag ||
	    dev->o_direct_flag || dev->nullio)
		goto out;

	/* ToDo: use sync_file_range() instead */
	fsync(vcmd->fd);

out:
	TRACE_EXIT_RES(res);
	return res;
}

static void exec_read(struct vdisk_cmd *vcmd, loff_t loff)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	int length = cmd->bufflen;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	int fd = vcmd->fd;
	loff_t err;

	TRACE_ENTRY();

	TRACE_DBG("reading off %"PRId64", len %d", loff, length);
	if (dev->nullio)
		err = length;
	else {
		/* SEEK */
		err = lseek64(fd, loff, 0/*SEEK_SET*/);
		if (err != loff) {
			PRINT_ERROR("lseek trouble %"PRId64" != %"PRId64
				" (errno %d)", (uint64_t)err, (uint64_t)loff,
				errno);
			set_cmd_error(vcmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
			goto out;
		}
		/* READ */
		err = read(fd, address, length);
	}

	if ((err < 0) || (err < length)) {
		PRINT_ERROR("read() returned %"PRId64" from %d (errno %d)",
			(uint64_t)err, length, errno);
		if (err == -EAGAIN)
			set_busy(vcmd);
		else {
			set_cmd_error(vcmd,
			    SCST_LOAD_SENSE(scst_sense_read_error));
		}
		goto out;
	}

	set_resp_data_len(vcmd, cmd->bufflen);

out:
	TRACE_EXIT();
	return;
}

static void exec_write(struct vdisk_cmd *vcmd, loff_t loff)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	loff_t err;
	int length = cmd->bufflen;
	uint8_t *address = (uint8_t*)(unsigned long)cmd->pbuf;
	int fd = vcmd->fd;

	TRACE_ENTRY();

restart:
	TRACE_DBG("writing off %"PRId64", len %d", loff, length);

	if (dev->nullio)
		err = length;
	else {
		/* SEEK */
		err = lseek64(fd, loff, 0/*SEEK_SET*/);
		if (err != loff) {
			PRINT_ERROR("lseek trouble %"PRId64" != %"PRId64
				" (errno %d)", (uint64_t)err, (uint64_t)loff,
				errno);
			set_cmd_error(vcmd,
			    SCST_LOAD_SENSE(scst_sense_hardw_error));
			goto out;
		}

		/* WRITE */
		err = write(fd, address, length);
	}

	if (err < 0) {
		PRINT_ERROR("write() returned %"PRId64" from %d (errno %d, "
			"cmd_h %x)", err, length, errno, vcmd->cmd->cmd_h);
		if (err == -EAGAIN)
			set_busy(vcmd);
		else {
			set_cmd_error(vcmd,
			    SCST_LOAD_SENSE(scst_sense_write_error));
		}
		goto out;
	} else if (err < length) {
		/*
		 * Probably that's wrong, but sometimes write() returns
		 * value less, than requested. Let's restart.
		 */
		TRACE_MGMT_DBG("write() returned %d from %d", (int)err, length);
		if (err == 0) {
			PRINT_INFO("Suspicious: write() returned 0 from "
				"%d", length);
		}
		length -= err;
		goto restart;
	}

out:
	TRACE_EXIT();
	return;
}

static void exec_verify(struct vdisk_cmd *vcmd, loff_t loff)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	loff_t err;
	int64_t length = cmd->bufflen;
	uint8_t *address = (uint8_t *)(unsigned long)cmd->pbuf;
	int compare;
	int fd = vcmd->fd;
	uint8_t mem_verify[128*1024];

	TRACE_ENTRY();

	if (exec_fsync(vcmd) != 0)
		goto out;

	/*
	 * Until the cache is cleared prior the verifying, there is not
         * much point in this code. ToDo.
	 *
	 * Nevertherless, this code is valuable if the data have not read
	 * from the file/disk yet.
	 */

	/* SEEK */
	if (!dev->nullio) {
		err = lseek64(fd, loff, 0/*SEEK_SET*/);
		if (err != loff) {
			PRINT_ERROR("lseek trouble %"PRId64" != %"PRId64
				" (errno %d)", (uint64_t)err,
				(uint64_t)loff, errno);
			set_cmd_error(vcmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
			goto out;
		}
	}

	if ((length == 0) && (cmd->data_len != 0)) {
		length = cmd->data_len;
		compare = 0;
	} else
		compare = 1;

	while (length > 0) {
		int64_t len_mem = (length > (int)sizeof(mem_verify)) ?
					(int)sizeof(mem_verify) : length;
		TRACE_DBG("Verify: length %"PRId64" - len_mem %"PRId64,
			length, len_mem);

		if (!dev->nullio)
			err = read(fd, (char *)mem_verify, len_mem);
		else
			err = len_mem;
		if ((err < 0) || (err < len_mem)) {
			PRINT_ERROR("read() returned %"PRId64" from %"PRId64" "
				"(errno %d)", (uint64_t)err, len_mem, errno);
			if (err == -EAGAIN)
				set_busy(vcmd);
			else {
				set_cmd_error(vcmd,
				    SCST_LOAD_SENSE(scst_sense_read_error));
			}
			goto out;
		}
		if (compare && memcmp(address, mem_verify, len_mem) != 0) {
			TRACE_DBG("Verify: error memcmp length %"PRId64, length);
			set_cmd_error(vcmd,
			    SCST_LOAD_SENSE(scst_sense_miscompare_error));
			goto out;
		}
		length -= len_mem;
		address += len_mem;
	}

	if (length < 0) {
		PRINT_ERROR("Failure: %"PRId64, length);
		set_cmd_error(vcmd, SCST_LOAD_SENSE(scst_sense_hardw_error));
	}

out:
	TRACE_EXIT();
	return;
}

static void exec_write_same(struct vdisk_cmd *vcmd)
{
	struct vdisk_dev *dev = vcmd->dev;
	struct scst_user_scsi_cmd_exec *cmd = &vcmd->cmd->exec_cmd;
	struct scst_user_scsi_cmd_reply_exec *reply = &vcmd->reply->exec_reply;
	uint64_t blocks = cmd->data_len >> dev->block_shift;
	static struct scst_user_data_descriptor uwhere[3];

	TRACE_ENTRY();

	if (blocks < 2)
		goto out;

	/* It's only a debug code, so it's OK to use static descr */

	memset(uwhere, 0, sizeof(uwhere));

	uwhere[0].usdd_lba = cmd->lba;
	uwhere[0].usdd_blocks = 1;
	uwhere[1].usdd_lba = cmd->lba+1;
	uwhere[1].usdd_blocks = blocks-1;

	reply->reply_type = SCST_EXEC_REPLY_DO_WRITE_SAME;
	reply->ws_descriptors_len = sizeof(uwhere);
	reply->ws_descriptors = (unsigned long)uwhere;

out:
	TRACE_EXIT();
	return;
}