text: /*-
   *   BSD LICENSE
   *
   *   Copyright (c) Intel Corporation. All rights reserved.
   *   Copyright (c) 2019 Mellanox Technologies LTD. All rights reserved.
   *
   *   Redistribution and use in source and binary forms, with or without
   *   modification, are permitted provided that the following conditions
   *   are met:
   *
   *     * Redistributions of source code must retain the above copyright
   *       notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in
   *       the documentation and/or other materials provided with the
   *       distribution.
   *     * Neither the name of Intel Corporation nor the names of its
   *       contributors may be used to endorse or promote products derived
   *       from this software without specific prior written permission.
   *
   *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "spdk/stdinc.h"
  
  #include "nvmf_internal.h"
  #include "transport.h"
  
  #include "spdk/event.h"
  #include "spdk/likely.h"
  #include "spdk/string.h"
  #include "spdk/trace.h"
  #include "spdk/nvmf_spec.h"
  #include "spdk/uuid.h"
  #include "spdk/json.h"
  #include "spdk/file.h"
  
  #include "spdk/bdev_module.h"
  #include "spdk_internal/log.h"
  #include "spdk_internal/utf.h"
  
  #define MODEL_NUMBER_DEFAULT "SPDK bdev Controller"
  
  /*
   * States for parsing valid domains in NQNs according to RFC 1034
   */
  enum spdk_nvmf_nqn_domain_states {
  	/* First character of a domain must be a letter */
  	SPDK_NVMF_DOMAIN_ACCEPT_LETTER = 0,
  
  	/* Subsequent characters can be any of letter, digit, or hyphen */
  	SPDK_NVMF_DOMAIN_ACCEPT_LDH = 1,
  
  	/* A domain label must end with either a letter or digit */
  	SPDK_NVMF_DOMAIN_ACCEPT_ANY = 2
  };
  
  /* Returns true if is a valid ASCII string as defined by the NVMe spec */
  static bool
  spdk_nvmf_valid_ascii_string(const void *buf, size_t size)
  {
  	const uint8_t *str = buf;
  	size_t i;
  
  	for (i = 0; i < size; i++) {
  		if (str[i] < 0x20 || str[i] > 0x7E) {
  			return false;
  		}
  	}
  
  	return true;
  }
  
  static bool
  spdk_nvmf_valid_nqn(const char *nqn)
  {
  	size_t len;
  	struct spdk_uuid uuid_value;
  	uint32_t i;
  	int bytes_consumed;
  	uint32_t domain_label_length;
  	char *reverse_domain_end;
  	uint32_t reverse_domain_end_index;
  	enum spdk_nvmf_nqn_domain_states domain_state = SPDK_NVMF_DOMAIN_ACCEPT_LETTER;
  
  	/* Check for length requirements */
  	len = strlen(nqn);
  	if (len > SPDK_NVMF_NQN_MAX_LEN) {
  		SPDK_ERRLOG("Invalid NQN \"%s\": length %zu > max %d\n", nqn, len, SPDK_NVMF_NQN_MAX_LEN);
  		return false;
  	}
  
  	/* The nqn must be at least as long as SPDK_NVMF_NQN_MIN_LEN to contain the necessary prefix. */
  	if (len < SPDK_NVMF_NQN_MIN_LEN) {
  		SPDK_ERRLOG("Invalid NQN \"%s\": length %zu < min %d\n", nqn, len, SPDK_NVMF_NQN_MIN_LEN);
  		return false;
  	}
  
  	/* Check for discovery controller nqn */
  	if (!strcmp(nqn, SPDK_NVMF_DISCOVERY_NQN)) {
  		return true;
  	}
  
  	/* Check for equality with the generic nqn structure of the form "nqn.2014-08.org.nvmexpress:uuid:11111111-2222-3333-4444-555555555555" */
  	if (!strncmp(nqn, SPDK_NVMF_NQN_UUID_PRE, SPDK_NVMF_NQN_UUID_PRE_LEN)) {
  		if (len != SPDK_NVMF_NQN_UUID_PRE_LEN + SPDK_NVMF_UUID_STRING_LEN) {
  			SPDK_ERRLOG("Invalid NQN \"%s\": uuid is not the correct length\n", nqn);
  			return false;
  		}
  
  		if (spdk_uuid_parse(&uuid_value, &nqn[SPDK_NVMF_NQN_UUID_PRE_LEN])) {
  			SPDK_ERRLOG("Invalid NQN \"%s\": uuid is not formatted correctly\n", nqn);
  			return false;
  		}
  		return true;
  	}
  
  	/* If the nqn does not match the uuid structure, the next several checks validate the form "nqn.yyyy-mm.reverse.domain:user-string" */
  
  	if (strncmp(nqn, "nqn.", 4) != 0) {
  		SPDK_ERRLOG("Invalid NQN \"%s\": NQN must begin with \"nqn.\".\n", nqn);
  		return false;
  	}
  
  	/* Check for yyyy-mm. */
  	if (!(isdigit(nqn[4]) && isdigit(nqn[5]) && isdigit(nqn[6]) && isdigit(nqn[7]) &&
  	      nqn[8] == '-' && isdigit(nqn[9]) && isdigit(nqn[10]) && nqn[11] == '.')) {
  		SPDK_ERRLOG("Invalid date code in NQN \"%s\"\n", nqn);
  		return false;
  	}
  
  	reverse_domain_end = strchr(nqn, ':');
  	if (reverse_domain_end != NULL && (reverse_domain_end_index = reverse_domain_end - nqn) < len - 1) {
  	} else {
  		SPDK_ERRLOG("Invalid NQN \"%s\". NQN must contain user specified name with a ':' as a prefix.\n",
  			    nqn);
  		return false;
  	}
  
  	/* Check for valid reverse domain */
  	domain_label_length = 0;
  	for (i = 12; i < reverse_domain_end_index; i++) {
  		if (domain_label_length > SPDK_DOMAIN_LABEL_MAX_LEN) {
  			SPDK_ERRLOG("Invalid domain name in NQN \"%s\". At least one Label is too long.\n", nqn);
  			return false;
  		}
  
  		switch (domain_state) {
  
  		case SPDK_NVMF_DOMAIN_ACCEPT_LETTER: {
  			if (isalpha(nqn[i])) {
  				domain_state = SPDK_NVMF_DOMAIN_ACCEPT_ANY;
  				domain_label_length++;
  				break;
  			} else {
  				SPDK_ERRLOG("Invalid domain name in NQN \"%s\". Label names must start with a letter.\n", nqn);
  				return false;
  			}
  		}
  
  		case SPDK_NVMF_DOMAIN_ACCEPT_LDH: {
  			if (isalpha(nqn[i]) || isdigit(nqn[i])) {
  				domain_state = SPDK_NVMF_DOMAIN_ACCEPT_ANY;
  				domain_label_length++;
  				break;
  			} else if (nqn[i] == '-') {
  				if (i == reverse_domain_end_index - 1) {
  					SPDK_ERRLOG("Invalid domain name in NQN \"%s\". Label names must end with an alphanumeric symbol.\n",
  						    nqn);
  					return false;
  				}
  				domain_state = SPDK_NVMF_DOMAIN_ACCEPT_LDH;
  				domain_label_length++;
  				break;
  			} else if (nqn[i] == '.') {
  				SPDK_ERRLOG("Invalid domain name in NQN \"%s\". Label names must end with an alphanumeric symbol.\n",
  					    nqn);
  				return false;
  			} else {
  				SPDK_ERRLOG("Invalid domain name in NQN \"%s\". Label names must contain only [a-z,A-Z,0-9,'-','.'].\n",
  					    nqn);
  				return false;
  			}
  		}
  
  		case SPDK_NVMF_DOMAIN_ACCEPT_ANY: {
  			if (isalpha(nqn[i]) || isdigit(nqn[i])) {
  				domain_state = SPDK_NVMF_DOMAIN_ACCEPT_ANY;
  				domain_label_length++;
  				break;
  			} else if (nqn[i] == '-') {
  				if (i == reverse_domain_end_index - 1) {
  					SPDK_ERRLOG("Invalid domain name in NQN \"%s\". Label names must end with an alphanumeric symbol.\n",
  						    nqn);
  					return false;
  				}
  				domain_state = SPDK_NVMF_DOMAIN_ACCEPT_LDH;
  				domain_label_length++;
  				break;
  			} else if (nqn[i] == '.') {
  				domain_state = SPDK_NVMF_DOMAIN_ACCEPT_LETTER;
  				domain_label_length = 0;
  				break;
  			} else {
  				SPDK_ERRLOG("Invalid domain name in NQN \"%s\". Label names must contain only [a-z,A-Z,0-9,'-','.'].\n",
  					    nqn);
  				return false;
  			}
  		}
  		}
  	}
  
  	i = reverse_domain_end_index + 1;
  	while (i < len) {
  		bytes_consumed = utf8_valid(&nqn[i], &nqn[len]);
  		if (bytes_consumed <= 0) {
  			SPDK_ERRLOG("Invalid domain name in NQN \"%s\". Label names must contain only valid utf-8.\n", nqn);
  			return false;
  		}
  
  		i += bytes_consumed;
  	}
  	return true;
  }
  
  struct spdk_nvmf_subsystem *
  spdk_nvmf_subsystem_create(struct spdk_nvmf_tgt *tgt,
  			   const char *nqn,
  			   enum spdk_nvmf_subtype type,
  			   uint32_t num_ns)
  {
  	struct spdk_nvmf_subsystem	*subsystem;
  	uint32_t			sid;
  
  	if (spdk_nvmf_tgt_find_subsystem(tgt, nqn)) {
  		SPDK_ERRLOG("Subsystem NQN '%s' already exists\n", nqn);
  		return NULL;
  	}
  
  	if (!spdk_nvmf_valid_nqn(nqn)) {
  		return NULL;
  	}
  
  	if (type == SPDK_NVMF_SUBTYPE_DISCOVERY && num_ns != 0) {
  		SPDK_ERRLOG("Discovery subsystem cannot have namespaces.\n");
  		return NULL;
  	}
  
  	/* Find a free subsystem id (sid) */
  	for (sid = 0; sid < tgt->max_subsystems; sid++) {
  		if (tgt->subsystems[sid] == NULL) {
  			break;
  		}
  	}
  	if (sid >= tgt->max_subsystems) {
  		return NULL;
  	}
  
  	subsystem = calloc(1, sizeof(struct spdk_nvmf_subsystem));
  	if (subsystem == NULL) {
  		return NULL;
  	}
  
  	subsystem->thread = spdk_get_thread();
  	subsystem->state = SPDK_NVMF_SUBSYSTEM_INACTIVE;
  	subsystem->tgt = tgt;
  	subsystem->id = sid;
  	subsystem->subtype = type;
  	subsystem->max_nsid = num_ns;
  	subsystem->max_allowed_nsid = num_ns;
  	subsystem->next_cntlid = 0;
  	snprintf(subsystem->subnqn, sizeof(subsystem->subnqn), "%s", nqn);
  	TAILQ_INIT(&subsystem->listeners);
  	TAILQ_INIT(&subsystem->hosts);
  	TAILQ_INIT(&subsystem->ctrlrs);
  
  	if (num_ns != 0) {
  		subsystem->ns = calloc(num_ns, sizeof(struct spdk_nvmf_ns *));
  		if (subsystem->ns == NULL) {
  			SPDK_ERRLOG("Namespace memory allocation failed\n");
  			free(subsystem);
  			return NULL;
  		}
  	}
  
  	memset(subsystem->sn, '0', sizeof(subsystem->sn) - 1);
  	subsystem->sn[sizeof(subsystem->sn) - 1] = '\0';
  
  	snprintf(subsystem->mn, sizeof(subsystem->mn), "%s",
  		 MODEL_NUMBER_DEFAULT);
  
  	tgt->subsystems[sid] = subsystem;
  	tgt->discovery_genctr++;
  
  	return subsystem;
  }
  
  static void
  _spdk_nvmf_subsystem_remove_host(struct spdk_nvmf_subsystem *subsystem, struct spdk_nvmf_host *host)
  {
  	TAILQ_REMOVE(&subsystem->hosts, host, link);
  	free(host);
  }
  
  static void
  _nvmf_subsystem_remove_listener(struct spdk_nvmf_subsystem *subsystem,
  				struct spdk_nvmf_listener *listener)
  {
  	struct spdk_nvmf_transport *transport;
  
  	transport = spdk_nvmf_tgt_get_transport(subsystem->tgt, listener->trid.trtype);
  	if (transport != NULL) {
  		spdk_nvmf_transport_stop_listen(transport, &listener->trid);
  	}
  
  	TAILQ_REMOVE(&subsystem->listeners, listener, link);
  	free(listener);
  }
  
  void
  spdk_nvmf_subsystem_destroy(struct spdk_nvmf_subsystem *subsystem)
  {
  	struct spdk_nvmf_listener	*listener, *listener_tmp;
  	struct spdk_nvmf_host		*host, *host_tmp;
  	struct spdk_nvmf_ctrlr		*ctrlr, *ctrlr_tmp;
  	struct spdk_nvmf_ns		*ns;
  
  	if (!subsystem) {
  		return;
  	}
  
  	assert(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE);
  
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "subsystem is %p\n", subsystem);
  
  	TAILQ_FOREACH_SAFE(listener, &subsystem->listeners, link, listener_tmp) {
  		_nvmf_subsystem_remove_listener(subsystem, listener);
  	}
  
  	TAILQ_FOREACH_SAFE(host, &subsystem->hosts, link, host_tmp) {
  		_spdk_nvmf_subsystem_remove_host(subsystem, host);
  	}
  
  	TAILQ_FOREACH_SAFE(ctrlr, &subsystem->ctrlrs, link, ctrlr_tmp) {
  		spdk_nvmf_ctrlr_destruct(ctrlr);
  	}
  
  	ns = spdk_nvmf_subsystem_get_first_ns(subsystem);
  	while (ns != NULL) {
  		struct spdk_nvmf_ns *next_ns = spdk_nvmf_subsystem_get_next_ns(subsystem, ns);
  
  		spdk_nvmf_subsystem_remove_ns(subsystem, ns->opts.nsid);
  		ns = next_ns;
  	}
  
  	free(subsystem->ns);
  
  	subsystem->tgt->subsystems[subsystem->id] = NULL;
  	subsystem->tgt->discovery_genctr++;
  
  	free(subsystem);
  }
  
  static int
  spdk_nvmf_subsystem_set_state(struct spdk_nvmf_subsystem *subsystem,
  			      enum spdk_nvmf_subsystem_state state)
  {
  	enum spdk_nvmf_subsystem_state actual_old_state, expected_old_state;
  	bool exchanged;
  
  	switch (state) {
  	case SPDK_NVMF_SUBSYSTEM_INACTIVE:
  		expected_old_state = SPDK_NVMF_SUBSYSTEM_DEACTIVATING;
  		break;
  	case SPDK_NVMF_SUBSYSTEM_ACTIVATING:
  		expected_old_state = SPDK_NVMF_SUBSYSTEM_INACTIVE;
  		break;
  	case SPDK_NVMF_SUBSYSTEM_ACTIVE:
  		expected_old_state = SPDK_NVMF_SUBSYSTEM_ACTIVATING;
  		break;
  	case SPDK_NVMF_SUBSYSTEM_PAUSING:
  		expected_old_state = SPDK_NVMF_SUBSYSTEM_ACTIVE;
  		break;
  	case SPDK_NVMF_SUBSYSTEM_PAUSED:
  		expected_old_state = SPDK_NVMF_SUBSYSTEM_PAUSING;
  		break;
  	case SPDK_NVMF_SUBSYSTEM_RESUMING:
  		expected_old_state = SPDK_NVMF_SUBSYSTEM_PAUSED;
  		break;
  	case SPDK_NVMF_SUBSYSTEM_DEACTIVATING:
  		expected_old_state = SPDK_NVMF_SUBSYSTEM_ACTIVE;
  		break;
  	default:
  		assert(false);
  		return -1;
  	}
  
  	actual_old_state = expected_old_state;
  	exchanged = __atomic_compare_exchange_n(&subsystem->state, &actual_old_state, state, false,
  						__ATOMIC_RELAXED, __ATOMIC_RELAXED);
  	if (spdk_unlikely(exchanged == false)) {
  		if (actual_old_state == SPDK_NVMF_SUBSYSTEM_RESUMING &&
  		    state == SPDK_NVMF_SUBSYSTEM_ACTIVE) {
  			expected_old_state = SPDK_NVMF_SUBSYSTEM_RESUMING;
  		}
  		/* This is for the case when activating the subsystem fails. */
  		if (actual_old_state == SPDK_NVMF_SUBSYSTEM_ACTIVATING &&
  		    state == SPDK_NVMF_SUBSYSTEM_DEACTIVATING) {
  			expected_old_state = SPDK_NVMF_SUBSYSTEM_ACTIVATING;
  		}
  		actual_old_state = expected_old_state;
  		__atomic_compare_exchange_n(&subsystem->state, &actual_old_state, state, false,
  					    __ATOMIC_RELAXED, __ATOMIC_RELAXED);
  	}
  	assert(actual_old_state == expected_old_state);
  	return actual_old_state - expected_old_state;
  }
  
  struct subsystem_state_change_ctx {
  	struct spdk_nvmf_subsystem *subsystem;
  
  	enum spdk_nvmf_subsystem_state requested_state;
  
  	spdk_nvmf_subsystem_state_change_done cb_fn;
  	void *cb_arg;
  };
  
  static void
  subsystem_state_change_done(struct spdk_io_channel_iter *i, int status)
  {
  	struct subsystem_state_change_ctx *ctx = spdk_io_channel_iter_get_ctx(i);
  
  	if (status == 0) {
  		status = spdk_nvmf_subsystem_set_state(ctx->subsystem, ctx->requested_state);
  		if (status) {
  			status = -1;
  		}
  	}
  
  	if (ctx->cb_fn) {
  		ctx->cb_fn(ctx->subsystem, ctx->cb_arg, status);
  	}
  	free(ctx);
  }
  
  static void
  subsystem_state_change_continue(void *ctx, int status)
  {
  	struct spdk_io_channel_iter *i = ctx;
  	spdk_for_each_channel_continue(i, status);
  }
  
  static void
  subsystem_state_change_on_pg(struct spdk_io_channel_iter *i)
  {
  	struct subsystem_state_change_ctx *ctx;
  	struct spdk_io_channel *ch;
  	struct spdk_nvmf_poll_group *group;
  
  	ctx = spdk_io_channel_iter_get_ctx(i);
  	ch = spdk_io_channel_iter_get_channel(i);
  	group = spdk_io_channel_get_ctx(ch);
  
  	switch (ctx->requested_state) {
  	case SPDK_NVMF_SUBSYSTEM_INACTIVE:
  		spdk_nvmf_poll_group_remove_subsystem(group, ctx->subsystem, subsystem_state_change_continue, i);
  		break;
  	case SPDK_NVMF_SUBSYSTEM_ACTIVE:
  		if (ctx->subsystem->state == SPDK_NVMF_SUBSYSTEM_ACTIVATING) {
  			spdk_nvmf_poll_group_add_subsystem(group, ctx->subsystem, subsystem_state_change_continue, i);
  		} else if (ctx->subsystem->state == SPDK_NVMF_SUBSYSTEM_RESUMING) {
  			spdk_nvmf_poll_group_resume_subsystem(group, ctx->subsystem, subsystem_state_change_continue, i);
  		}
  		break;
  	case SPDK_NVMF_SUBSYSTEM_PAUSED:
  		spdk_nvmf_poll_group_pause_subsystem(group, ctx->subsystem, subsystem_state_change_continue, i);
  		break;
  	default:
  		assert(false);
  		break;
  	}
  }
  
  static int
  spdk_nvmf_subsystem_state_change(struct spdk_nvmf_subsystem *subsystem,
  				 enum spdk_nvmf_subsystem_state requested_state,
  				 spdk_nvmf_subsystem_state_change_done cb_fn,
  				 void *cb_arg)
  {
  	struct subsystem_state_change_ctx *ctx;
  	enum spdk_nvmf_subsystem_state intermediate_state;
  	int rc;
  
  	switch (requested_state) {
  	case SPDK_NVMF_SUBSYSTEM_INACTIVE:
  		intermediate_state = SPDK_NVMF_SUBSYSTEM_DEACTIVATING;
  		break;
  	case SPDK_NVMF_SUBSYSTEM_ACTIVE:
  		if (subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED) {
  			intermediate_state = SPDK_NVMF_SUBSYSTEM_RESUMING;
  		} else {
  			intermediate_state = SPDK_NVMF_SUBSYSTEM_ACTIVATING;
  		}
  		break;
  	case SPDK_NVMF_SUBSYSTEM_PAUSED:
  		intermediate_state = SPDK_NVMF_SUBSYSTEM_PAUSING;
  		break;
  	default:
  		assert(false);
  		return -EINVAL;
  	}
  
  	ctx = calloc(1, sizeof(*ctx));
  	if (!ctx) {
  		return -ENOMEM;
  	}
  
  	rc = spdk_nvmf_subsystem_set_state(subsystem, intermediate_state);
  	if (rc) {
  		free(ctx);
  		return rc;
  	}
  
  	ctx->subsystem = subsystem;
  	ctx->requested_state = requested_state;
  	ctx->cb_fn = cb_fn;
  	ctx->cb_arg = cb_arg;
  
  	spdk_for_each_channel(subsystem->tgt,
  			      subsystem_state_change_on_pg,
  			      ctx,
  			      subsystem_state_change_done);
  
  	return 0;
  }
  
  int
  spdk_nvmf_subsystem_start(struct spdk_nvmf_subsystem *subsystem,
  			  spdk_nvmf_subsystem_state_change_done cb_fn,
  			  void *cb_arg)
  {
  	return spdk_nvmf_subsystem_state_change(subsystem, SPDK_NVMF_SUBSYSTEM_ACTIVE, cb_fn, cb_arg);
  }
  
  int
  spdk_nvmf_subsystem_stop(struct spdk_nvmf_subsystem *subsystem,
  			 spdk_nvmf_subsystem_state_change_done cb_fn,
  			 void *cb_arg)
  {
  	return spdk_nvmf_subsystem_state_change(subsystem, SPDK_NVMF_SUBSYSTEM_INACTIVE, cb_fn, cb_arg);
  }
  
  int
  spdk_nvmf_subsystem_pause(struct spdk_nvmf_subsystem *subsystem,
  			  spdk_nvmf_subsystem_state_change_done cb_fn,
  			  void *cb_arg)
  {
  	return spdk_nvmf_subsystem_state_change(subsystem, SPDK_NVMF_SUBSYSTEM_PAUSED, cb_fn, cb_arg);
  }
  
  int
  spdk_nvmf_subsystem_resume(struct spdk_nvmf_subsystem *subsystem,
  			   spdk_nvmf_subsystem_state_change_done cb_fn,
  			   void *cb_arg)
  {
  	return spdk_nvmf_subsystem_state_change(subsystem, SPDK_NVMF_SUBSYSTEM_ACTIVE, cb_fn, cb_arg);
  }
  
  struct spdk_nvmf_subsystem *
  spdk_nvmf_subsystem_get_first(struct spdk_nvmf_tgt *tgt)
  {
  	struct spdk_nvmf_subsystem	*subsystem;
  	uint32_t sid;
  
  	for (sid = 0; sid < tgt->max_subsystems; sid++) {
  		subsystem = tgt->subsystems[sid];
  		if (subsystem) {
  			return subsystem;
  		}
  	}
  
  	return NULL;
  }
  
  struct spdk_nvmf_subsystem *
  spdk_nvmf_subsystem_get_next(struct spdk_nvmf_subsystem *subsystem)
  {
  	uint32_t sid;
  	struct spdk_nvmf_tgt *tgt;
  
  	if (!subsystem) {
  		return NULL;
  	}
  
  	tgt = subsystem->tgt;
  
  	for (sid = subsystem->id + 1; sid < tgt->max_subsystems; sid++) {
  		subsystem = tgt->subsystems[sid];
  		if (subsystem) {
  			return subsystem;
  		}
  	}
  
  	return NULL;
  }
  
  static struct spdk_nvmf_host *
  _spdk_nvmf_subsystem_find_host(struct spdk_nvmf_subsystem *subsystem, const char *hostnqn)
  {
  	struct spdk_nvmf_host *host = NULL;
  
  	TAILQ_FOREACH(host, &subsystem->hosts, link) {
  		if (strcmp(hostnqn, host->nqn) == 0) {
  			return host;
  		}
  	}
  
  	return NULL;
  }
  
  int
  spdk_nvmf_subsystem_add_host(struct spdk_nvmf_subsystem *subsystem, const char *hostnqn)
  {
  	struct spdk_nvmf_host *host;
  
  	if (!spdk_nvmf_valid_nqn(hostnqn)) {
  		return -EINVAL;
  	}
  
  	if (!(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE ||
  	      subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED)) {
  		return -EAGAIN;
  	}
  
  	if (_spdk_nvmf_subsystem_find_host(subsystem, hostnqn)) {
  		/* This subsystem already allows the specified host. */
  		return 0;
  	}
  
  	host = calloc(1, sizeof(*host));
  	if (!host) {
  		return -ENOMEM;
  	}
  
  	snprintf(host->nqn, sizeof(host->nqn), "%s", hostnqn);
  
  	TAILQ_INSERT_HEAD(&subsystem->hosts, host, link);
  	subsystem->tgt->discovery_genctr++;
  
  	return 0;
  }
  
  int
  spdk_nvmf_subsystem_remove_host(struct spdk_nvmf_subsystem *subsystem, const char *hostnqn)
  {
  	struct spdk_nvmf_host *host;
  
  	if (!(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE ||
  	      subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED)) {
  		return -EAGAIN;
  	}
  
  	host = _spdk_nvmf_subsystem_find_host(subsystem, hostnqn);
  	if (host == NULL) {
  		return -ENOENT;
  	}
  
  	_spdk_nvmf_subsystem_remove_host(subsystem, host);
  	return 0;
  }
  
  int
  spdk_nvmf_subsystem_set_allow_any_host(struct spdk_nvmf_subsystem *subsystem, bool allow_any_host)
  {
  	if (!(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE ||
  	      subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED)) {
  		return -EAGAIN;
  	}
  
  	subsystem->allow_any_host = allow_any_host;
  
  	return 0;
  }
  
  bool
  spdk_nvmf_subsystem_get_allow_any_host(const struct spdk_nvmf_subsystem *subsystem)
  {
  	return subsystem->allow_any_host;
  }
  
  bool
  spdk_nvmf_subsystem_host_allowed(struct spdk_nvmf_subsystem *subsystem, const char *hostnqn)
  {
  	if (!hostnqn) {
  		return false;
  	}
  
  	if (subsystem->allow_any_host) {
  		return true;
  	}
  
  	return _spdk_nvmf_subsystem_find_host(subsystem, hostnqn) != NULL;
  }
  
  struct spdk_nvmf_host *
  spdk_nvmf_subsystem_get_first_host(struct spdk_nvmf_subsystem *subsystem)
  {
  	return TAILQ_FIRST(&subsystem->hosts);
  }
  
  
  struct spdk_nvmf_host *
  spdk_nvmf_subsystem_get_next_host(struct spdk_nvmf_subsystem *subsystem,
  				  struct spdk_nvmf_host *prev_host)
  {
  	return TAILQ_NEXT(prev_host, link);
  }
  
  const char *
  spdk_nvmf_host_get_nqn(struct spdk_nvmf_host *host)
  {
  	return host->nqn;
  }
  
  static struct spdk_nvmf_listener *
  _spdk_nvmf_subsystem_find_listener(struct spdk_nvmf_subsystem *subsystem,
  				   const struct spdk_nvme_transport_id *trid)
  {
  	struct spdk_nvmf_listener *listener;
  
  	TAILQ_FOREACH(listener, &subsystem->listeners, link) {
  		if (spdk_nvme_transport_id_compare(&listener->trid, trid) == 0) {
  			return listener;
  		}
  	}
  
  	return NULL;
  }
  
  int
  spdk_nvmf_subsystem_add_listener(struct spdk_nvmf_subsystem *subsystem,
  				 struct spdk_nvme_transport_id *trid)
  {
  	struct spdk_nvmf_transport *transport;
  	struct spdk_nvmf_listener *listener;
  
  	if (!(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE ||
  	      subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED)) {
  		return -EAGAIN;
  	}
  
  	if (_spdk_nvmf_subsystem_find_listener(subsystem, trid)) {
  		/* Listener already exists in this subsystem */
  		return 0;
  	}
  
  	transport = spdk_nvmf_tgt_get_transport(subsystem->tgt, trid->trtype);
  	if (transport == NULL) {
  		SPDK_ERRLOG("Unknown transport type %d\n", trid->trtype);
  		return -EINVAL;
  	}
  
  	listener = calloc(1, sizeof(*listener));
  	if (!listener) {
  		return -ENOMEM;
  	}
  
  	listener->trid = *trid;
  	listener->transport = transport;
  
  	TAILQ_INSERT_HEAD(&subsystem->listeners, listener, link);
  
  	return 0;
  }
  
  int
  spdk_nvmf_subsystem_remove_listener(struct spdk_nvmf_subsystem *subsystem,
  				    const struct spdk_nvme_transport_id *trid)
  {
  	struct spdk_nvmf_listener *listener;
  
  	if (!(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE ||
  	      subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED)) {
  		return -EAGAIN;
  	}
  
  	listener = _spdk_nvmf_subsystem_find_listener(subsystem, trid);
  	if (listener == NULL) {
  		return -ENOENT;
  	}
  
  	_nvmf_subsystem_remove_listener(subsystem, listener);
  
  	return 0;
  }
  
  bool
  spdk_nvmf_subsystem_listener_allowed(struct spdk_nvmf_subsystem *subsystem,
  				     struct spdk_nvme_transport_id *trid)
  {
  	struct spdk_nvmf_listener *listener;
  
  	if (!strcmp(subsystem->subnqn, SPDK_NVMF_DISCOVERY_NQN)) {
  		return true;
  	}
  
  	TAILQ_FOREACH(listener, &subsystem->listeners, link) {
  		if (spdk_nvme_transport_id_compare(&listener->trid, trid) == 0) {
  			return true;
  		}
  	}
  
  	return false;
  }
  
  struct spdk_nvmf_listener *
  spdk_nvmf_subsystem_get_first_listener(struct spdk_nvmf_subsystem *subsystem)
  {
  	return TAILQ_FIRST(&subsystem->listeners);
  }
  
  struct spdk_nvmf_listener *
  spdk_nvmf_subsystem_get_next_listener(struct spdk_nvmf_subsystem *subsystem,
  				      struct spdk_nvmf_listener *prev_listener)
  {
  	return TAILQ_NEXT(prev_listener, link);
  }
  
  const struct spdk_nvme_transport_id *
  spdk_nvmf_listener_get_trid(struct spdk_nvmf_listener *listener)
  {
  	return &listener->trid;
  }
  
  void
  spdk_nvmf_subsystem_allow_any_listener(struct spdk_nvmf_subsystem *subsystem,
  				       bool allow_any_listener)
  {
  	subsystem->allow_any_listener = allow_any_listener;
  }
  
  bool
  spdk_nvmf_subsytem_any_listener_allowed(struct spdk_nvmf_subsystem *subsystem)
  {
  	return subsystem->allow_any_listener;
  }
  
  
  struct subsystem_update_ns_ctx {
  	struct spdk_nvmf_subsystem *subsystem;
  
  	spdk_nvmf_subsystem_state_change_done cb_fn;
  	void *cb_arg;
  };
  
  static void
  subsystem_update_ns_done(struct spdk_io_channel_iter *i, int status)
  {
  	struct subsystem_update_ns_ctx *ctx = spdk_io_channel_iter_get_ctx(i);
  
  	if (ctx->cb_fn) {
  		ctx->cb_fn(ctx->subsystem, ctx->cb_arg, status);
  	}
  	free(ctx);
  }
  
  static void
  subsystem_update_ns_on_pg(struct spdk_io_channel_iter *i)
  {
  	int rc;
  	struct subsystem_update_ns_ctx *ctx;
  	struct spdk_nvmf_poll_group *group;
  	struct spdk_nvmf_subsystem *subsystem;
  
  	ctx = spdk_io_channel_iter_get_ctx(i);
  	group = spdk_io_channel_get_ctx(spdk_io_channel_iter_get_channel(i));
  	subsystem = ctx->subsystem;
  
  	rc = spdk_nvmf_poll_group_update_subsystem(group, subsystem);
  	spdk_for_each_channel_continue(i, rc);
  }
  
  static int
  spdk_nvmf_subsystem_update_ns(struct spdk_nvmf_subsystem *subsystem, spdk_channel_for_each_cpl cpl,
  			      void *ctx)
  {
  	spdk_for_each_channel(subsystem->tgt,
  			      subsystem_update_ns_on_pg,
  			      ctx,
  			      cpl);
  
  	return 0;
  }
  
  static void
  spdk_nvmf_subsystem_ns_changed(struct spdk_nvmf_subsystem *subsystem, uint32_t nsid)
  {
  	struct spdk_nvmf_ctrlr *ctrlr;
  
  	TAILQ_FOREACH(ctrlr, &subsystem->ctrlrs, link) {
  		spdk_nvmf_ctrlr_ns_changed(ctrlr, nsid);
  	}
  }
  
  int
  spdk_nvmf_subsystem_remove_ns(struct spdk_nvmf_subsystem *subsystem, uint32_t nsid)
  {
  	struct spdk_nvmf_ns *ns;
  	struct spdk_nvmf_registrant *reg, *reg_tmp;
  
  	if (!(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE ||
  	      subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED)) {
  		assert(false);
  		return -1;
  	}
  
  	if (nsid == 0 || nsid > subsystem->max_nsid) {
  		return -1;
  	}
  
  	ns = subsystem->ns[nsid - 1];
  	if (!ns) {
  		return -1;
  	}
  
  	subsystem->ns[nsid - 1] = NULL;
  
  	TAILQ_FOREACH_SAFE(reg, &ns->registrants, link, reg_tmp) {
  		TAILQ_REMOVE(&ns->registrants, reg, link);
  		free(reg);
  	}
  	spdk_bdev_module_release_bdev(ns->bdev);
  	spdk_bdev_close(ns->desc);
  	if (ns->ptpl_file) {
  		free(ns->ptpl_file);
  	}
  	free(ns);
  
  	spdk_nvmf_subsystem_ns_changed(subsystem, nsid);
  
  	return 0;
  }
  
  static void
  _spdk_nvmf_ns_hot_remove(struct spdk_nvmf_subsystem *subsystem,
  			 void *cb_arg, int status)
  {
  	struct spdk_nvmf_ns *ns = cb_arg;
  	int rc;
  
  	rc = spdk_nvmf_subsystem_remove_ns(subsystem, ns->opts.nsid);
  	if (rc != 0) {
  		SPDK_ERRLOG("Failed to make changes to NVME-oF subsystem with id: %u\n", subsystem->id);
  	}
  
  	spdk_nvmf_subsystem_resume(subsystem, NULL, NULL);
  }
  
  static void
  spdk_nvmf_ns_hot_remove(void *remove_ctx)
  {
  	struct spdk_nvmf_ns *ns = remove_ctx;
  	int rc;
  
  	rc = spdk_nvmf_subsystem_pause(ns->subsystem, _spdk_nvmf_ns_hot_remove, ns);
  	if (rc) {
  		SPDK_ERRLOG("Unable to pause subsystem to process namespace removal!\n");
  	}
  }
  
  static void
  _spdk_nvmf_ns_resize(struct spdk_nvmf_subsystem *subsystem, void *cb_arg, int status)
  {
  	struct spdk_nvmf_ns *ns = cb_arg;
  
  	spdk_nvmf_subsystem_ns_changed(subsystem, ns->opts.nsid);
  	spdk_nvmf_subsystem_resume(subsystem, NULL, NULL);
  }
  
  static void
  spdk_nvmf_ns_resize(void *event_ctx)
  {
  	struct spdk_nvmf_ns *ns = event_ctx;
  	int rc;
  
  	rc = spdk_nvmf_subsystem_pause(ns->subsystem, _spdk_nvmf_ns_resize, ns);
  	if (rc) {
  		SPDK_ERRLOG("Unable to pause subsystem to process namespace resize!\n");
  	}
  }
  
  static void
  spdk_nvmf_ns_event(enum spdk_bdev_event_type type,
  		   struct spdk_bdev *bdev,
  		   void *event_ctx)
  {
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Bdev event: type %d, name %s, subsystem_id %d, ns_id %d\n",
  		      type,
  		      bdev->name,
  		      ((struct spdk_nvmf_ns *)event_ctx)->subsystem->id,
  		      ((struct spdk_nvmf_ns *)event_ctx)->nsid);
  
  	switch (type) {
  	case SPDK_BDEV_EVENT_REMOVE:
  		spdk_nvmf_ns_hot_remove(event_ctx);
  		break;
  	case SPDK_BDEV_EVENT_RESIZE:
  		spdk_nvmf_ns_resize(event_ctx);
  		break;
  	default:
  		SPDK_NOTICELOG("Unsupported bdev event: type %d\n", type);
  		break;
  	}
  }
  
  void
  spdk_nvmf_ns_opts_get_defaults(struct spdk_nvmf_ns_opts *opts, size_t opts_size)
  {
  	/* All current fields are set to 0 by default. */
  	memset(opts, 0, opts_size);
  }
  
  /* Dummy bdev module used to to claim bdevs. */
  static struct spdk_bdev_module ns_bdev_module = {
  	.name	= "NVMe-oF Target",
  };
  
  static int
  spdk_nvmf_ns_load_reservation(const char *file, struct spdk_nvmf_reservation_info *info);
  static int
  nvmf_ns_reservation_restore(struct spdk_nvmf_ns *ns, struct spdk_nvmf_reservation_info *info);
  
  uint32_t
  spdk_nvmf_subsystem_add_ns(struct spdk_nvmf_subsystem *subsystem, struct spdk_bdev *bdev,
  			   const struct spdk_nvmf_ns_opts *user_opts, size_t opts_size,
  			   const char *ptpl_file)
  {
  	struct spdk_nvmf_ns_opts opts;
  	struct spdk_nvmf_ns *ns;
  	struct spdk_nvmf_reservation_info info = {0};
  	int rc;
  
  	if (!(subsystem->state == SPDK_NVMF_SUBSYSTEM_INACTIVE ||
  	      subsystem->state == SPDK_NVMF_SUBSYSTEM_PAUSED)) {
  		return 0;
  	}
  
  	if (spdk_bdev_get_md_size(bdev) != 0 && !spdk_bdev_is_md_interleaved(bdev)) {
  		SPDK_ERRLOG("Can't attach bdev with separate metadata.\n");
  		return 0;
  	}
  
  	spdk_nvmf_ns_opts_get_defaults(&opts, sizeof(opts));
  	if (user_opts) {
  		memcpy(&opts, user_opts, spdk_min(sizeof(opts), opts_size));
  	}
  
  	if (spdk_mem_all_zero(&opts.uuid, sizeof(opts.uuid))) {
  		opts.uuid = *spdk_bdev_get_uuid(bdev);
  	}
  
  	if (opts.nsid == SPDK_NVME_GLOBAL_NS_TAG) {
  		SPDK_ERRLOG("Invalid NSID %" PRIu32 "\n", opts.nsid);
  		return 0;
  	}
  
  	if (opts.nsid == 0) {
  		/*
  		 * NSID not specified - find a free index.
  		 *
  		 * If no free slots are found, opts.nsid will be subsystem->max_nsid + 1, which will
  		 * expand max_nsid if possible.
  		 */
  		for (opts.nsid = 1; opts.nsid <= subsystem->max_nsid; opts.nsid++) {
  			if (_spdk_nvmf_subsystem_get_ns(subsystem, opts.nsid) == NULL) {
  				break;
  			}
  		}
  	}
  
  	if (_spdk_nvmf_subsystem_get_ns(subsystem, opts.nsid)) {
  		SPDK_ERRLOG("Requested NSID %" PRIu32 " already in use\n", opts.nsid);
  		return 0;
  	}
  
  	if (opts.nsid > subsystem->max_nsid) {
  		struct spdk_nvmf_ns **new_ns_array;
  
  		/* If MaxNamespaces was specified, we can't extend max_nsid beyond it. */
  		if (subsystem->max_allowed_nsid > 0 && opts.nsid > subsystem->max_allowed_nsid) {
  			SPDK_ERRLOG("Can't extend NSID range above MaxNamespaces\n");
  			return 0;
  		}
  
  		/* If a controller is connected, we can't change NN. */
  		if (!TAILQ_EMPTY(&subsystem->ctrlrs)) {
  			SPDK_ERRLOG("Can't extend NSID range while controllers are connected\n");
  			return 0;
  		}
  
  		new_ns_array = realloc(subsystem->ns, sizeof(struct spdk_nvmf_ns *) * opts.nsid);
  		if (new_ns_array == NULL) {
  			SPDK_ERRLOG("Memory allocation error while resizing namespace array.\n");
  			return 0;
  		}
  
  		memset(new_ns_array + subsystem->max_nsid, 0,
  		       sizeof(struct spdk_nvmf_ns *) * (opts.nsid - subsystem->max_nsid));
  		subsystem->ns = new_ns_array;
  		subsystem->max_nsid = opts.nsid;
  	}
  
  	ns = calloc(1, sizeof(*ns));
  	if (ns == NULL) {
  		SPDK_ERRLOG("Namespace allocation failed\n");
  		return 0;
  	}
  
  	ns->bdev = bdev;
  	ns->opts = opts;
  	ns->subsystem = subsystem;
  	rc = spdk_bdev_open_ext(bdev->name, true, spdk_nvmf_ns_event, ns, &ns->desc);
  	if (rc != 0) {
  		SPDK_ERRLOG("Subsystem %s: bdev %s cannot be opened, error=%d\n",
  			    subsystem->subnqn, spdk_bdev_get_name(bdev), rc);
  		free(ns);
  		return 0;
  	}
  	rc = spdk_bdev_module_claim_bdev(bdev, ns->desc, &ns_bdev_module);
  	if (rc != 0) {
  		spdk_bdev_close(ns->desc);
  		free(ns);
  		return 0;
  	}
  	subsystem->ns[opts.nsid - 1] = ns;
  	ns->nsid = opts.nsid;
  	TAILQ_INIT(&ns->registrants);
  
  	if (ptpl_file) {
  		rc = spdk_nvmf_ns_load_reservation(ptpl_file, &info);
  		if (!rc) {
  			rc = nvmf_ns_reservation_restore(ns, &info);
  			if (rc) {
  				SPDK_ERRLOG("Subsystem restore reservation failed\n");
  				subsystem->ns[opts.nsid - 1] = NULL;
  				spdk_bdev_close(ns->desc);
  				free(ns);
  				return 0;
  			}
  		}
  		ns->ptpl_file = strdup(ptpl_file);
  	}
  
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Subsystem %s: bdev %s assigned nsid %" PRIu32 "\n",
  		      spdk_nvmf_subsystem_get_nqn(subsystem),
  		      spdk_bdev_get_name(bdev),
  		      opts.nsid);
  
  	spdk_nvmf_subsystem_ns_changed(subsystem, opts.nsid);
  
  	return opts.nsid;
  }
  
  static uint32_t
  spdk_nvmf_subsystem_get_next_allocated_nsid(struct spdk_nvmf_subsystem *subsystem,
  		uint32_t prev_nsid)
  {
  	uint32_t nsid;
  
  	if (prev_nsid >= subsystem->max_nsid) {
  		return 0;
  	}
  
  	for (nsid = prev_nsid + 1; nsid <= subsystem->max_nsid; nsid++) {
  		if (subsystem->ns[nsid - 1]) {
  			return nsid;
  		}
  	}
  
  	return 0;
  }
  
  struct spdk_nvmf_ns *
  spdk_nvmf_subsystem_get_first_ns(struct spdk_nvmf_subsystem *subsystem)
  {
  	uint32_t first_nsid;
  
  	first_nsid = spdk_nvmf_subsystem_get_next_allocated_nsid(subsystem, 0);
  	return _spdk_nvmf_subsystem_get_ns(subsystem, first_nsid);
  }
  
  struct spdk_nvmf_ns *
  spdk_nvmf_subsystem_get_next_ns(struct spdk_nvmf_subsystem *subsystem,
  				struct spdk_nvmf_ns *prev_ns)
  {
  	uint32_t next_nsid;
  
  	next_nsid = spdk_nvmf_subsystem_get_next_allocated_nsid(subsystem, prev_ns->opts.nsid);
  	return _spdk_nvmf_subsystem_get_ns(subsystem, next_nsid);
  }
  
  struct spdk_nvmf_ns *
  spdk_nvmf_subsystem_get_ns(struct spdk_nvmf_subsystem *subsystem, uint32_t nsid)
  {
  	return _spdk_nvmf_subsystem_get_ns(subsystem, nsid);
  }
  
  uint32_t
  spdk_nvmf_ns_get_id(const struct spdk_nvmf_ns *ns)
  {
  	return ns->opts.nsid;
  }
  
  struct spdk_bdev *
  spdk_nvmf_ns_get_bdev(struct spdk_nvmf_ns *ns)
  {
  	return ns->bdev;
  }
  
  void
  spdk_nvmf_ns_get_opts(const struct spdk_nvmf_ns *ns, struct spdk_nvmf_ns_opts *opts,
  		      size_t opts_size)
  {
  	memset(opts, 0, opts_size);
  	memcpy(opts, &ns->opts, spdk_min(sizeof(ns->opts), opts_size));
  }
  
  const char *
  spdk_nvmf_subsystem_get_sn(const struct spdk_nvmf_subsystem *subsystem)
  {
  	return subsystem->sn;
  }
  
  int
  spdk_nvmf_subsystem_set_sn(struct spdk_nvmf_subsystem *subsystem, const char *sn)
  {
  	size_t len, max_len;
  
  	max_len = sizeof(subsystem->sn) - 1;
  	len = strlen(sn);
  	if (len > max_len) {
  		SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Invalid sn \"%s\": length %zu > max %zu\n",
  			      sn, len, max_len);
  		return -1;
  	}
  
  	if (!spdk_nvmf_valid_ascii_string(sn, len)) {
  		SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Non-ASCII sn\n");
  		SPDK_LOGDUMP(SPDK_LOG_NVMF, "sn", sn, len);
  		return -1;
  	}
  
  	snprintf(subsystem->sn, sizeof(subsystem->sn), "%s", sn);
  
  	return 0;
  }
  
  const char *
  spdk_nvmf_subsystem_get_mn(const struct spdk_nvmf_subsystem *subsystem)
  {
  	return subsystem->mn;
  }
  
  int
  spdk_nvmf_subsystem_set_mn(struct spdk_nvmf_subsystem *subsystem, const char *mn)
  {
  	size_t len, max_len;
  
  	if (mn == NULL) {
  		mn = MODEL_NUMBER_DEFAULT;
  	}
  	max_len = sizeof(subsystem->mn) - 1;
  	len = strlen(mn);
  	if (len > max_len) {
  		SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Invalid mn \"%s\": length %zu > max %zu\n",
  			      mn, len, max_len);
  		return -1;
  	}
  
  	if (!spdk_nvmf_valid_ascii_string(mn, len)) {
  		SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Non-ASCII mn\n");
  		SPDK_LOGDUMP(SPDK_LOG_NVMF, "mn", mn, len);
  		return -1;
  	}
  
  	snprintf(subsystem->mn, sizeof(subsystem->mn), "%s", mn);
  
  	return 0;
  }
  
  const char *
  spdk_nvmf_subsystem_get_nqn(struct spdk_nvmf_subsystem *subsystem)
  {
  	return subsystem->subnqn;
  }
  
  /* Workaround for astyle formatting bug */
  typedef enum spdk_nvmf_subtype nvmf_subtype_t;
  
  nvmf_subtype_t
  spdk_nvmf_subsystem_get_type(struct spdk_nvmf_subsystem *subsystem)
  {
  	return subsystem->subtype;
  }
  
  static uint16_t
  spdk_nvmf_subsystem_gen_cntlid(struct spdk_nvmf_subsystem *subsystem)
  {
  	int count;
  
  	/*
  	 * In the worst case, we might have to try all CNTLID values between 1 and 0xFFF0 - 1
  	 * before we find one that is unused (or find that all values are in use).
  	 */
  	for (count = 0; count < 0xFFF0 - 1; count++) {
  		subsystem->next_cntlid++;
  		if (subsystem->next_cntlid >= 0xFFF0) {
  			/* The spec reserves cntlid values in the range FFF0h to FFFFh. */
  			subsystem->next_cntlid = 1;
  		}
  
  		/* Check if a controller with this cntlid currently exists. */
  		if (spdk_nvmf_subsystem_get_ctrlr(subsystem, subsystem->next_cntlid) == NULL) {
  			/* Found unused cntlid */
  			return subsystem->next_cntlid;
  		}
  	}
  
  	/* All valid cntlid values are in use. */
  	return 0xFFFF;
  }
  
  int
  spdk_nvmf_subsystem_add_ctrlr(struct spdk_nvmf_subsystem *subsystem, struct spdk_nvmf_ctrlr *ctrlr)
  {
  	ctrlr->cntlid = spdk_nvmf_subsystem_gen_cntlid(subsystem);
  	if (ctrlr->cntlid == 0xFFFF) {
  		/* Unable to get a cntlid */
  		SPDK_ERRLOG("Reached max simultaneous ctrlrs\n");
  		return -EBUSY;
  	}
  
  	TAILQ_INSERT_TAIL(&subsystem->ctrlrs, ctrlr, link);
  
  	return 0;
  }
  
  void
  spdk_nvmf_subsystem_remove_ctrlr(struct spdk_nvmf_subsystem *subsystem,
  				 struct spdk_nvmf_ctrlr *ctrlr)
  {
  	assert(subsystem == ctrlr->subsys);
  	TAILQ_REMOVE(&subsystem->ctrlrs, ctrlr, link);
  }
  
  struct spdk_nvmf_ctrlr *
  spdk_nvmf_subsystem_get_ctrlr(struct spdk_nvmf_subsystem *subsystem, uint16_t cntlid)
  {
  	struct spdk_nvmf_ctrlr *ctrlr;
  
  	TAILQ_FOREACH(ctrlr, &subsystem->ctrlrs, link) {
  		if (ctrlr->cntlid == cntlid) {
  			return ctrlr;
  		}
  	}
  
  	return NULL;
  }
  
  uint32_t
  spdk_nvmf_subsystem_get_max_namespaces(const struct spdk_nvmf_subsystem *subsystem)
  {
  	return subsystem->max_allowed_nsid;
  }
  
  struct _nvmf_ns_registrant {
  	uint64_t		rkey;
  	char			*host_uuid;
  };
  
  struct _nvmf_ns_registrants {
  	size_t				num_regs;
  	struct _nvmf_ns_registrant	reg[SPDK_NVMF_MAX_NUM_REGISTRANTS];
  };
  
  struct _nvmf_ns_reservation {
  	bool					ptpl_activated;
  	enum spdk_nvme_reservation_type		rtype;
  	uint64_t				crkey;
  	char					*bdev_uuid;
  	char					*holder_uuid;
  	struct _nvmf_ns_registrants		regs;
  };
  
  static const struct spdk_json_object_decoder nvmf_ns_pr_reg_decoders[] = {
  	{"rkey", offsetof(struct _nvmf_ns_registrant, rkey), spdk_json_decode_uint64},
  	{"host_uuid", offsetof(struct _nvmf_ns_registrant, host_uuid), spdk_json_decode_string},
  };
  
  static int
  nvmf_decode_ns_pr_reg(const struct spdk_json_val *val, void *out)
  {
  	struct _nvmf_ns_registrant *reg = out;
  
  	return spdk_json_decode_object(val, nvmf_ns_pr_reg_decoders,
  				       SPDK_COUNTOF(nvmf_ns_pr_reg_decoders), reg);
  }
  
  static int
  nvmf_decode_ns_pr_regs(const struct spdk_json_val *val, void *out)
  {
  	struct _nvmf_ns_registrants *regs = out;
  
  	return spdk_json_decode_array(val, nvmf_decode_ns_pr_reg, regs->reg,
  				      SPDK_NVMF_MAX_NUM_REGISTRANTS, &regs->num_regs,
  				      sizeof(struct _nvmf_ns_registrant));
  }
  
  static const struct spdk_json_object_decoder nvmf_ns_pr_decoders[] = {
  	{"ptpl", offsetof(struct _nvmf_ns_reservation, ptpl_activated), spdk_json_decode_bool, true},
  	{"rtype", offsetof(struct _nvmf_ns_reservation, rtype), spdk_json_decode_uint32, true},
  	{"crkey", offsetof(struct _nvmf_ns_reservation, crkey), spdk_json_decode_uint64, true},
  	{"bdev_uuid", offsetof(struct _nvmf_ns_reservation, bdev_uuid), spdk_json_decode_string},
  	{"holder_uuid", offsetof(struct _nvmf_ns_reservation, holder_uuid), spdk_json_decode_string, true},
  	{"registrants", offsetof(struct _nvmf_ns_reservation, regs), nvmf_decode_ns_pr_regs},
  };
  
  static int
  spdk_nvmf_ns_load_reservation(const char *file, struct spdk_nvmf_reservation_info *info)
  {
  	FILE *fd;
  	size_t json_size;
  	ssize_t values_cnt, rc;
  	void *json = NULL, *end;
  	struct spdk_json_val *values = NULL;
  	struct _nvmf_ns_reservation res = {};
  	uint32_t i;
  
  	fd = fopen(file, "r");
  	/* It's not an error if the file does not exist */
  	if (!fd) {
  		SPDK_NOTICELOG("File %s does not exist\n", file);
  		return -ENOENT;
  	}
  
  	/* Load all persist file contents into a local buffer */
  	json = spdk_posix_file_load(fd, &json_size);
  	fclose(fd);
  	if (!json) {
  		SPDK_ERRLOG("Load persit file %s failed\n", file);
  		return -ENOMEM;
  	}
  
  	rc = spdk_json_parse(json, json_size, NULL, 0, &end, 0);
  	if (rc < 0) {
  		SPDK_NOTICELOG("Parsing JSON configuration failed (%zd)\n", rc);
  		goto exit;
  	}
  
  	values_cnt = rc;
  	values = calloc(values_cnt, sizeof(struct spdk_json_val));
  	if (values == NULL) {
  		goto exit;
  	}
  
  	rc = spdk_json_parse(json, json_size, values, values_cnt, &end, 0);
  	if (rc != values_cnt) {
  		SPDK_ERRLOG("Parsing JSON configuration failed (%zd)\n", rc);
  		goto exit;
  	}
  
  	/* Decode json */
  	if (spdk_json_decode_object(values, nvmf_ns_pr_decoders,
  				    SPDK_COUNTOF(nvmf_ns_pr_decoders),
  				    &res)) {
  		SPDK_ERRLOG("Invalid objects in the persist file %s\n", file);
  		rc = -EINVAL;
  		goto exit;
  	}
  
  	if (res.regs.num_regs > SPDK_NVMF_MAX_NUM_REGISTRANTS) {
  		SPDK_ERRLOG("Can only support up to %u registrants\n", SPDK_NVMF_MAX_NUM_REGISTRANTS);
  		rc = -ERANGE;
  		goto exit;
  	}
  
  	rc = 0;
  	info->ptpl_activated = res.ptpl_activated;
  	info->rtype = res.rtype;
  	info->crkey = res.crkey;
  	snprintf(info->bdev_uuid, sizeof(info->bdev_uuid), "%s", res.bdev_uuid);
  	snprintf(info->holder_uuid, sizeof(info->holder_uuid), "%s", res.holder_uuid);
  	info->num_regs = res.regs.num_regs;
  	for (i = 0; i < res.regs.num_regs; i++) {
  		info->registrants[i].rkey = res.regs.reg[i].rkey;
  		snprintf(info->registrants[i].host_uuid, sizeof(info->registrants[i].host_uuid), "%s",
  			 res.regs.reg[i].host_uuid);
  	}
  
  exit:
  	free(json);
  	free(values);
  	free(res.bdev_uuid);
  	free(res.holder_uuid);
  	for (i = 0; i < res.regs.num_regs; i++) {
  		free(res.regs.reg[i].host_uuid);
  	}
  
  	return rc;
  }
  
  static bool
  nvmf_ns_reservation_all_registrants_type(struct spdk_nvmf_ns *ns);
  
  static int
  nvmf_ns_reservation_restore(struct spdk_nvmf_ns *ns, struct spdk_nvmf_reservation_info *info)
  {
  	uint32_t i;
  	struct spdk_nvmf_registrant *reg, *holder = NULL;
  	struct spdk_uuid bdev_uuid, holder_uuid;
  
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "NSID %u, PTPL %u, Number of registrants %u\n",
  		      ns->nsid, info->ptpl_activated, info->num_regs);
  
  	/* it's not an error */
  	if (!info->ptpl_activated || !info->num_regs) {
  		return 0;
  	}
  
  	spdk_uuid_parse(&bdev_uuid, info->bdev_uuid);
  	if (spdk_uuid_compare(&bdev_uuid, spdk_bdev_get_uuid(ns->bdev))) {
  		SPDK_ERRLOG("Existing bdev UUID is not same with configuration file\n");
  		return -EINVAL;
  	}
  
  	ns->crkey = info->crkey;
  	ns->rtype = info->rtype;
  	ns->ptpl_activated = info->ptpl_activated;
  	spdk_uuid_parse(&holder_uuid, info->holder_uuid);
  
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Bdev UUID %s\n", info->bdev_uuid);
  	if (info->rtype) {
  		SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Holder UUID %s, RTYPE %u, RKEY 0x%"PRIx64"\n",
  			      info->holder_uuid, info->rtype, info->crkey);
  	}
  
  	for (i = 0; i < info->num_regs; i++) {
  		reg = calloc(1, sizeof(*reg));
  		if (!reg) {
  			return -ENOMEM;
  		}
  		spdk_uuid_parse(&reg->hostid, info->registrants[i].host_uuid);
  		reg->rkey = info->registrants[i].rkey;
  		TAILQ_INSERT_TAIL(&ns->registrants, reg, link);
  		if (!spdk_uuid_compare(&holder_uuid, &reg->hostid)) {
  			holder = reg;
  		}
  		SPDK_DEBUGLOG(SPDK_LOG_NVMF, "Registrant RKEY 0x%"PRIx64", Host UUID %s\n",
  			      info->registrants[i].rkey, info->registrants[i].host_uuid);
  	}
  
  	if (nvmf_ns_reservation_all_registrants_type(ns)) {
  		ns->holder = TAILQ_FIRST(&ns->registrants);
  	} else {
  		ns->holder = holder;
  	}
  
  	return 0;
  }
  
  static int
  spdk_nvmf_ns_json_write_cb(void *cb_ctx, const void *data, size_t size)
  {
  	char *file = cb_ctx;
  	size_t rc;
  	FILE *fd;
  
  	fd = fopen(file, "w");
  	if (!fd) {
  		SPDK_ERRLOG("Can't open file %s for write\n", file);
  		return -ENOENT;
  	}
  	rc = fwrite(data, 1, size, fd);
  	fclose(fd);
  
  	return rc == size ? 0 : -1;
  }
  
  static int
  spdk_nvmf_ns_reservation_update(const char *file, struct spdk_nvmf_reservation_info *info)
  {
  	struct spdk_json_write_ctx *w;
  	uint32_t i;
  	int rc = 0;
  
  	w = spdk_json_write_begin(spdk_nvmf_ns_json_write_cb, (void *)file, 0);
  	if (w == NULL) {
  		return -ENOMEM;
  	}
  	/* clear the configuration file */
  	if (!info->ptpl_activated) {
  		goto exit;
  	}
  
  	spdk_json_write_object_begin(w);
  	spdk_json_write_named_bool(w, "ptpl", info->ptpl_activated);
  	spdk_json_write_named_uint32(w, "rtype", info->rtype);
  	spdk_json_write_named_uint64(w, "crkey", info->crkey);
  	spdk_json_write_named_string(w, "bdev_uuid", info->bdev_uuid);
  	spdk_json_write_named_string(w, "holder_uuid", info->holder_uuid);
  
  	spdk_json_write_named_array_begin(w, "registrants");
  	for (i = 0; i < info->num_regs; i++) {
  		spdk_json_write_object_begin(w);
  		spdk_json_write_named_uint64(w, "rkey", info->registrants[i].rkey);
  		spdk_json_write_named_string(w, "host_uuid", info->registrants[i].host_uuid);
  		spdk_json_write_object_end(w);
  	}
  	spdk_json_write_array_end(w);
  	spdk_json_write_object_end(w);
  
  exit:
  	rc = spdk_json_write_end(w);
  	return rc;
  }
  
  static int
  nvmf_ns_update_reservation_info(struct spdk_nvmf_ns *ns)
  {
  	struct spdk_nvmf_reservation_info info;
  	struct spdk_nvmf_registrant *reg, *tmp;
  	uint32_t i = 0;
  
  	assert(ns != NULL);
  
  	if (!ns->bdev || !ns->ptpl_file) {
  		return 0;
  	}
  
  	memset(&info, 0, sizeof(info));
  	spdk_uuid_fmt_lower(info.bdev_uuid, sizeof(info.bdev_uuid), spdk_bdev_get_uuid(ns->bdev));
  
  	if (ns->rtype) {
  		info.rtype = ns->rtype;
  		info.crkey = ns->crkey;
  		if (!nvmf_ns_reservation_all_registrants_type(ns)) {
  			assert(ns->holder != NULL);
  			spdk_uuid_fmt_lower(info.holder_uuid, sizeof(info.holder_uuid), &ns->holder->hostid);
  		}
  	}
  
  	TAILQ_FOREACH_SAFE(reg, &ns->registrants, link, tmp) {
  		spdk_uuid_fmt_lower(info.registrants[i].host_uuid, sizeof(info.registrants[i].host_uuid),
  				    &reg->hostid);
  		info.registrants[i++].rkey = reg->rkey;
  	}
  
  	info.num_regs = i;
  	info.ptpl_activated = ns->ptpl_activated;
  
  	return spdk_nvmf_ns_reservation_update(ns->ptpl_file, &info);
  }
  
  static struct spdk_nvmf_registrant *
  nvmf_ns_reservation_get_registrant(struct spdk_nvmf_ns *ns,
  				   struct spdk_uuid *uuid)
  {
  	struct spdk_nvmf_registrant *reg, *tmp;
  
  	TAILQ_FOREACH_SAFE(reg, &ns->registrants, link, tmp) {
  		if (!spdk_uuid_compare(&reg->hostid, uuid)) {
  			return reg;
  		}
  	}
  
  	return NULL;
  }
  
  /* Generate reservation notice log to registered HostID controllers */
  static void
  nvmf_subsystem_gen_ctrlr_notification(struct spdk_nvmf_subsystem *subsystem,
  				      struct spdk_nvmf_ns *ns,
  				      struct spdk_uuid *hostid_list,
  				      uint32_t num_hostid,
  				      enum spdk_nvme_reservation_notification_log_page_type type)
  {
  	struct spdk_nvmf_ctrlr *ctrlr;
  	uint32_t i;
  
  	for (i = 0; i < num_hostid; i++) {
  		TAILQ_FOREACH(ctrlr, &subsystem->ctrlrs, link) {
  			if (!spdk_uuid_compare(&ctrlr->hostid, &hostid_list[i])) {
  				spdk_nvmf_ctrlr_reservation_notice_log(ctrlr, ns, type);
  			}
  		}
  	}
  }
  
  /* Get all registrants' hostid other than the controller who issued the command */
  static uint32_t
  nvmf_ns_reservation_get_all_other_hostid(struct spdk_nvmf_ns *ns,
  		struct spdk_uuid *hostid_list,
  		uint32_t max_num_hostid,
  		struct spdk_uuid *current_hostid)
  {
  	struct spdk_nvmf_registrant *reg, *tmp;
  	uint32_t num_hostid = 0;
  
  	TAILQ_FOREACH_SAFE(reg, &ns->registrants, link, tmp) {
  		if (spdk_uuid_compare(&reg->hostid, current_hostid)) {
  			if (num_hostid == max_num_hostid) {
  				assert(false);
  				return max_num_hostid;
  			}
  			hostid_list[num_hostid++] = reg->hostid;
  		}
  	}
  
  	return num_hostid;
  }
  
  /* Calculate the unregistered HostID list according to list
   * prior to execute preempt command and list after executing
   * preempt command.
   */
  static uint32_t
  nvmf_ns_reservation_get_unregistered_hostid(struct spdk_uuid *old_hostid_list,
  		uint32_t old_num_hostid,
  		struct spdk_uuid *remaining_hostid_list,
  		uint32_t remaining_num_hostid)
  {
  	struct spdk_uuid temp_hostid_list[SPDK_NVMF_MAX_NUM_REGISTRANTS];
  	uint32_t i, j, num_hostid = 0;
  	bool found;
  
  	if (!remaining_num_hostid) {
  		return old_num_hostid;
  	}
  
  	for (i = 0; i < old_num_hostid; i++) {
  		found = false;
  		for (j = 0; j < remaining_num_hostid; j++) {
  			if (!spdk_uuid_compare(&old_hostid_list[i], &remaining_hostid_list[j])) {
  				found = true;
  				break;
  			}
  		}
  		if (!found) {
  			spdk_uuid_copy(&temp_hostid_list[num_hostid++], &old_hostid_list[i]);
  		}
  	}
  
  	if (num_hostid) {
  		memcpy(old_hostid_list, temp_hostid_list, sizeof(struct spdk_uuid) * num_hostid);
  	}
  
  	return num_hostid;
  }
  
  /* current reservation type is all registrants or not */
  static bool
  nvmf_ns_reservation_all_registrants_type(struct spdk_nvmf_ns *ns)
  {
  	return (ns->rtype == SPDK_NVME_RESERVE_WRITE_EXCLUSIVE_ALL_REGS ||
  		ns->rtype == SPDK_NVME_RESERVE_EXCLUSIVE_ACCESS_ALL_REGS);
  }
  
  /* current registrant is reservation holder or not */
  static bool
  nvmf_ns_reservation_registrant_is_holder(struct spdk_nvmf_ns *ns,
  		struct spdk_nvmf_registrant *reg)
  {
  	if (!reg) {
  		return false;
  	}
  
  	if (nvmf_ns_reservation_all_registrants_type(ns)) {
  		return true;
  	}
  
  	return (ns->holder == reg);
  }
  
  static int
  nvmf_ns_reservation_add_registrant(struct spdk_nvmf_ns *ns,
  				   struct spdk_nvmf_ctrlr *ctrlr,
  				   uint64_t nrkey)
  {
  	struct spdk_nvmf_registrant *reg;
  
  	reg = calloc(1, sizeof(*reg));
  	if (!reg) {
  		return -ENOMEM;
  	}
  
  	reg->rkey = nrkey;
  	/* set hostid for the registrant */
  	spdk_uuid_copy(&reg->hostid, &ctrlr->hostid);
  	TAILQ_INSERT_TAIL(&ns->registrants, reg, link);
  	ns->gen++;
  
  	return 0;
  }
  
  static void
  nvmf_ns_reservation_release_reservation(struct spdk_nvmf_ns *ns)
  {
  	ns->rtype = 0;
  	ns->crkey = 0;
  	ns->holder = NULL;
  }
  
  /* release the reservation if the last registrant was removed */
  static void
  nvmf_ns_reservation_check_release_on_remove_registrant(struct spdk_nvmf_ns *ns,
  		struct spdk_nvmf_registrant *reg)
  {
  	struct spdk_nvmf_registrant *next_reg;
  
  	/* no reservation holder */
  	if (!ns->holder) {
  		assert(ns->rtype == 0);
  		return;
  	}
  
  	next_reg = TAILQ_FIRST(&ns->registrants);
  	if (next_reg && nvmf_ns_reservation_all_registrants_type(ns)) {
  		/* the next valid registrant is the new holder now */
  		ns->holder = next_reg;
  	} else if (nvmf_ns_reservation_registrant_is_holder(ns, reg)) {
  		/* release the reservation */
  		nvmf_ns_reservation_release_reservation(ns);
  	}
  }
  
  static void
  nvmf_ns_reservation_remove_registrant(struct spdk_nvmf_ns *ns,
  				      struct spdk_nvmf_registrant *reg)
  {
  	TAILQ_REMOVE(&ns->registrants, reg, link);
  	nvmf_ns_reservation_check_release_on_remove_registrant(ns, reg);
  	free(reg);
  	ns->gen++;
  	return;
  }
  
  static uint32_t
  nvmf_ns_reservation_remove_registrants_by_key(struct spdk_nvmf_ns *ns,
  		uint64_t rkey)
  {
  	struct spdk_nvmf_registrant *reg, *tmp;
  	uint32_t count = 0;
  
  	TAILQ_FOREACH_SAFE(reg, &ns->registrants, link, tmp) {
  		if (reg->rkey == rkey) {
  			nvmf_ns_reservation_remove_registrant(ns, reg);
  			count++;
  		}
  	}
  	return count;
  }
  
  static uint32_t
  nvmf_ns_reservation_remove_all_other_registrants(struct spdk_nvmf_ns *ns,
  		struct spdk_nvmf_registrant *reg)
  {
  	struct spdk_nvmf_registrant *reg_tmp, *reg_tmp2;
  	uint32_t count = 0;
  
  	TAILQ_FOREACH_SAFE(reg_tmp, &ns->registrants, link, reg_tmp2) {
  		if (reg_tmp != reg) {
  			nvmf_ns_reservation_remove_registrant(ns, reg_tmp);
  			count++;
  		}
  	}
  	return count;
  }
  
  static uint32_t
  nvmf_ns_reservation_clear_all_registrants(struct spdk_nvmf_ns *ns)
  {
  	struct spdk_nvmf_registrant *reg, *reg_tmp;
  	uint32_t count = 0;
  
  	TAILQ_FOREACH_SAFE(reg, &ns->registrants, link, reg_tmp) {
  		nvmf_ns_reservation_remove_registrant(ns, reg);
  		count++;
  	}
  	return count;
  }
  
  static void
  nvmf_ns_reservation_acquire_reservation(struct spdk_nvmf_ns *ns, uint64_t rkey,
  					enum spdk_nvme_reservation_type rtype,
  					struct spdk_nvmf_registrant *holder)
  {
  	ns->rtype = rtype;
  	ns->crkey = rkey;
  	assert(ns->holder == NULL);
  	ns->holder = holder;
  }
  
  static bool
  nvmf_ns_reservation_register(struct spdk_nvmf_ns *ns,
  			     struct spdk_nvmf_ctrlr *ctrlr,
  			     struct spdk_nvmf_request *req)
  {
  	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
  	uint8_t rrega, iekey, cptpl, rtype;
  	struct spdk_nvme_reservation_register_data key;
  	struct spdk_nvmf_registrant *reg;
  	uint8_t status = SPDK_NVME_SC_SUCCESS;
  	bool update_sgroup = false;
  	struct spdk_uuid hostid_list[SPDK_NVMF_MAX_NUM_REGISTRANTS];
  	uint32_t num_hostid = 0;
  	int rc;
  
  	rrega = cmd->cdw10 & 0x7u;
  	iekey = (cmd->cdw10 >> 3) & 0x1u;
  	cptpl = (cmd->cdw10 >> 30) & 0x3u;
  
  	if (req->data && req->length >= sizeof(key)) {
  		memcpy(&key, req->data, sizeof(key));
  	} else {
  		SPDK_ERRLOG("No key provided. Failing request.\n");
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		goto exit;
  	}
  
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "REGISTER: RREGA %u, IEKEY %u, CPTPL %u, "
  		      "NRKEY 0x%"PRIx64", NRKEY 0x%"PRIx64"\n",
  		      rrega, iekey, cptpl, key.crkey, key.nrkey);
  
  	if (cptpl == SPDK_NVME_RESERVE_PTPL_CLEAR_POWER_ON) {
  		/* Ture to OFF state, and need to be updated in the configuration file */
  		if (ns->ptpl_activated) {
  			ns->ptpl_activated = 0;
  			update_sgroup = true;
  		}
  	} else if (cptpl == SPDK_NVME_RESERVE_PTPL_PERSIST_POWER_LOSS) {
  		if (ns->ptpl_file == NULL) {
  			status = SPDK_NVME_SC_INVALID_FIELD;
  			goto exit;
  		} else if (ns->ptpl_activated == 0) {
  			ns->ptpl_activated = 1;
  			update_sgroup = true;
  		}
  	}
  
  	/* current Host Identifier has registrant or not */
  	reg = nvmf_ns_reservation_get_registrant(ns, &ctrlr->hostid);
  
  	switch (rrega) {
  	case SPDK_NVME_RESERVE_REGISTER_KEY:
  		if (!reg) {
  			/* register new controller */
  			if (key.nrkey == 0) {
  				SPDK_ERRLOG("Can't register zeroed new key\n");
  				status = SPDK_NVME_SC_INVALID_FIELD;
  				goto exit;
  			}
  			rc = nvmf_ns_reservation_add_registrant(ns, ctrlr, key.nrkey);
  			if (rc < 0) {
  				status = SPDK_NVME_SC_INTERNAL_DEVICE_ERROR;
  				goto exit;
  			}
  			update_sgroup = true;
  		} else {
  			/* register with same key is not an error */
  			if (reg->rkey != key.nrkey) {
  				SPDK_ERRLOG("The same host already register a "
  					    "key with 0x%"PRIx64"\n",
  					    reg->rkey);
  				status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  				goto exit;
  			}
  		}
  		break;
  	case SPDK_NVME_RESERVE_UNREGISTER_KEY:
  		if (!reg || (!iekey && reg->rkey != key.crkey)) {
  			SPDK_ERRLOG("No registrant or current key doesn't match "
  				    "with existing registrant key\n");
  			status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  			goto exit;
  		}
  
  		rtype = ns->rtype;
  		num_hostid = nvmf_ns_reservation_get_all_other_hostid(ns, hostid_list,
  				SPDK_NVMF_MAX_NUM_REGISTRANTS,
  				&ctrlr->hostid);
  
  		nvmf_ns_reservation_remove_registrant(ns, reg);
  
  		if (!ns->rtype && num_hostid && (rtype == SPDK_NVME_RESERVE_WRITE_EXCLUSIVE_REG_ONLY ||
  						 rtype == SPDK_NVME_RESERVE_EXCLUSIVE_ACCESS_REG_ONLY)) {
  			nvmf_subsystem_gen_ctrlr_notification(ns->subsystem, ns,
  							      hostid_list,
  							      num_hostid,
  							      SPDK_NVME_RESERVATION_RELEASED);
  		}
  		update_sgroup = true;
  		break;
  	case SPDK_NVME_RESERVE_REPLACE_KEY:
  		if (!reg || (!iekey && reg->rkey != key.crkey)) {
  			SPDK_ERRLOG("No registrant or current key doesn't match "
  				    "with existing registrant key\n");
  			status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  			goto exit;
  		}
  		if (key.nrkey == 0) {
  			SPDK_ERRLOG("Can't register zeroed new key\n");
  			status = SPDK_NVME_SC_INVALID_FIELD;
  			goto exit;
  		}
  		reg->rkey = key.nrkey;
  		update_sgroup = true;
  		break;
  	default:
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		goto exit;
  	}
  
  exit:
  	if (update_sgroup) {
  		rc = nvmf_ns_update_reservation_info(ns);
  		if (rc != 0) {
  			status = SPDK_NVME_SC_INTERNAL_DEVICE_ERROR;
  		}
  	}
  	req->rsp->nvme_cpl.status.sct = SPDK_NVME_SCT_GENERIC;
  	req->rsp->nvme_cpl.status.sc = status;
  	return update_sgroup;
  }
  
  static bool
  nvmf_ns_reservation_acquire(struct spdk_nvmf_ns *ns,
  			    struct spdk_nvmf_ctrlr *ctrlr,
  			    struct spdk_nvmf_request *req)
  {
  	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
  	uint8_t racqa, iekey, rtype;
  	struct spdk_nvme_reservation_acquire_data key;
  	struct spdk_nvmf_registrant *reg;
  	bool all_regs = false;
  	uint32_t count = 0;
  	bool update_sgroup = true;
  	struct spdk_uuid hostid_list[SPDK_NVMF_MAX_NUM_REGISTRANTS];
  	uint32_t num_hostid = 0;
  	struct spdk_uuid new_hostid_list[SPDK_NVMF_MAX_NUM_REGISTRANTS];
  	uint32_t new_num_hostid = 0;
  	bool reservation_released = false;
  	uint8_t status = SPDK_NVME_SC_SUCCESS;
  
  	racqa = cmd->cdw10 & 0x7u;
  	iekey = (cmd->cdw10 >> 3) & 0x1u;
  	rtype = (cmd->cdw10 >> 8) & 0xffu;
  
  	if (req->data && req->length >= sizeof(key)) {
  		memcpy(&key, req->data, sizeof(key));
  	} else {
  		SPDK_ERRLOG("No key provided. Failing request.\n");
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		goto exit;
  	}
  
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "ACQUIRE: RACQA %u, IEKEY %u, RTYPE %u, "
  		      "NRKEY 0x%"PRIx64", PRKEY 0x%"PRIx64"\n",
  		      racqa, iekey, rtype, key.crkey, key.prkey);
  
  	if (iekey || rtype > SPDK_NVME_RESERVE_EXCLUSIVE_ACCESS_ALL_REGS) {
  		SPDK_ERRLOG("Ignore existing key field set to 1\n");
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		update_sgroup = false;
  		goto exit;
  	}
  
  	reg = nvmf_ns_reservation_get_registrant(ns, &ctrlr->hostid);
  	/* must be registrant and CRKEY must match */
  	if (!reg || reg->rkey != key.crkey) {
  		SPDK_ERRLOG("No registrant or current key doesn't match "
  			    "with existing registrant key\n");
  		status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  		update_sgroup = false;
  		goto exit;
  	}
  
  	all_regs = nvmf_ns_reservation_all_registrants_type(ns);
  
  	switch (racqa) {
  	case SPDK_NVME_RESERVE_ACQUIRE:
  		/* it's not an error for the holder to acquire same reservation type again */
  		if (nvmf_ns_reservation_registrant_is_holder(ns, reg) && ns->rtype == rtype) {
  			/* do nothing */
  			update_sgroup = false;
  		} else if (ns->holder == NULL) {
  			/* fisrt time to acquire the reservation */
  			nvmf_ns_reservation_acquire_reservation(ns, key.crkey, rtype, reg);
  		} else {
  			SPDK_ERRLOG("Invalid rtype or current registrant is not holder\n");
  			status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  			update_sgroup = false;
  			goto exit;
  		}
  		break;
  	case SPDK_NVME_RESERVE_PREEMPT:
  		/* no reservation holder */
  		if (!ns->holder) {
  			/* unregister with PRKEY */
  			nvmf_ns_reservation_remove_registrants_by_key(ns, key.prkey);
  			break;
  		}
  		num_hostid = nvmf_ns_reservation_get_all_other_hostid(ns, hostid_list,
  				SPDK_NVMF_MAX_NUM_REGISTRANTS,
  				&ctrlr->hostid);
  
  		/* only 1 reservation holder and reservation key is valid */
  		if (!all_regs) {
  			/* preempt itself */
  			if (nvmf_ns_reservation_registrant_is_holder(ns, reg) &&
  			    ns->crkey == key.prkey) {
  				ns->rtype = rtype;
  				reservation_released = true;
  				break;
  			}
  
  			if (ns->crkey == key.prkey) {
  				nvmf_ns_reservation_remove_registrant(ns, ns->holder);
  				nvmf_ns_reservation_acquire_reservation(ns, key.crkey, rtype, reg);
  				reservation_released = true;
  			} else if (key.prkey != 0) {
  				nvmf_ns_reservation_remove_registrants_by_key(ns, key.prkey);
  			} else {
  				/* PRKEY is zero */
  				SPDK_ERRLOG("Current PRKEY is zero\n");
  				status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  				update_sgroup = false;
  				goto exit;
  			}
  		} else {
  			/* release all other registrants except for the current one */
  			if (key.prkey == 0) {
  				nvmf_ns_reservation_remove_all_other_registrants(ns, reg);
  				assert(ns->holder == reg);
  			} else {
  				count = nvmf_ns_reservation_remove_registrants_by_key(ns, key.prkey);
  				if (count == 0) {
  					SPDK_ERRLOG("PRKEY doesn't match any registrant\n");
  					status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  					update_sgroup = false;
  					goto exit;
  				}
  			}
  		}
  		break;
  	default:
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		update_sgroup = false;
  		break;
  	}
  
  exit:
  	if (update_sgroup && racqa == SPDK_NVME_RESERVE_PREEMPT) {
  		new_num_hostid = nvmf_ns_reservation_get_all_other_hostid(ns, new_hostid_list,
  				 SPDK_NVMF_MAX_NUM_REGISTRANTS,
  				 &ctrlr->hostid);
  		/* Preempt notification occurs on the unregistered controllers
  		 * other than the controller who issued the command.
  		 */
  		num_hostid = nvmf_ns_reservation_get_unregistered_hostid(hostid_list,
  				num_hostid,
  				new_hostid_list,
  				new_num_hostid);
  		if (num_hostid) {
  			nvmf_subsystem_gen_ctrlr_notification(ns->subsystem, ns,
  							      hostid_list,
  							      num_hostid,
  							      SPDK_NVME_REGISTRATION_PREEMPTED);
  
  		}
  		/* Reservation released notification occurs on the
  		 * controllers which are the remaining registrants other than
  		 * the controller who issued the command.
  		 */
  		if (reservation_released && new_num_hostid) {
  			nvmf_subsystem_gen_ctrlr_notification(ns->subsystem, ns,
  							      new_hostid_list,
  							      new_num_hostid,
  							      SPDK_NVME_RESERVATION_RELEASED);
  
  		}
  	}
  	if (update_sgroup && ns->ptpl_activated) {
  		if (nvmf_ns_update_reservation_info(ns)) {
  			status = SPDK_NVME_SC_INTERNAL_DEVICE_ERROR;
  		}
  	}
  	req->rsp->nvme_cpl.status.sct = SPDK_NVME_SCT_GENERIC;
  	req->rsp->nvme_cpl.status.sc = status;
  	return update_sgroup;
  }
  
  static bool
  nvmf_ns_reservation_release(struct spdk_nvmf_ns *ns,
  			    struct spdk_nvmf_ctrlr *ctrlr,
  			    struct spdk_nvmf_request *req)
  {
  	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
  	uint8_t rrela, iekey, rtype;
  	struct spdk_nvmf_registrant *reg;
  	uint64_t crkey;
  	uint8_t status = SPDK_NVME_SC_SUCCESS;
  	bool update_sgroup = true;
  	struct spdk_uuid hostid_list[SPDK_NVMF_MAX_NUM_REGISTRANTS];
  	uint32_t num_hostid = 0;
  
  	rrela = cmd->cdw10 & 0x7u;
  	iekey = (cmd->cdw10 >> 3) & 0x1u;
  	rtype = (cmd->cdw10 >> 8) & 0xffu;
  
  	if (req->data && req->length >= sizeof(crkey)) {
  		memcpy(&crkey, req->data, sizeof(crkey));
  	} else {
  		SPDK_ERRLOG("No key provided. Failing request.\n");
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		goto exit;
  	}
  
  	SPDK_DEBUGLOG(SPDK_LOG_NVMF, "RELEASE: RRELA %u, IEKEY %u, RTYPE %u, "
  		      "CRKEY 0x%"PRIx64"\n",  rrela, iekey, rtype, crkey);
  
  	if (iekey) {
  		SPDK_ERRLOG("Ignore existing key field set to 1\n");
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		update_sgroup = false;
  		goto exit;
  	}
  
  	reg = nvmf_ns_reservation_get_registrant(ns, &ctrlr->hostid);
  	if (!reg || reg->rkey != crkey) {
  		SPDK_ERRLOG("No registrant or current key doesn't match "
  			    "with existing registrant key\n");
  		status = SPDK_NVME_SC_RESERVATION_CONFLICT;
  		update_sgroup = false;
  		goto exit;
  	}
  
  	num_hostid = nvmf_ns_reservation_get_all_other_hostid(ns, hostid_list,
  			SPDK_NVMF_MAX_NUM_REGISTRANTS,
  			&ctrlr->hostid);
  
  	switch (rrela) {
  	case SPDK_NVME_RESERVE_RELEASE:
  		if (!ns->holder) {
  			SPDK_DEBUGLOG(SPDK_LOG_NVMF, "RELEASE: no holder\n");
  			update_sgroup = false;
  			goto exit;
  		}
  		if (ns->rtype != rtype) {
  			SPDK_ERRLOG("Type doesn't match\n");
  			status = SPDK_NVME_SC_INVALID_FIELD;
  			update_sgroup = false;
  			goto exit;
  		}
  		if (!nvmf_ns_reservation_registrant_is_holder(ns, reg)) {
  			/* not the reservation holder, this isn't an error */
  			update_sgroup = false;
  			goto exit;
  		}
  
  		rtype = ns->rtype;
  		nvmf_ns_reservation_release_reservation(ns);
  
  		if (num_hostid && rtype != SPDK_NVME_RESERVE_WRITE_EXCLUSIVE &&
  		    rtype != SPDK_NVME_RESERVE_EXCLUSIVE_ACCESS) {
  			nvmf_subsystem_gen_ctrlr_notification(ns->subsystem, ns,
  							      hostid_list,
  							      num_hostid,
  							      SPDK_NVME_RESERVATION_RELEASED);
  		}
  		break;
  	case SPDK_NVME_RESERVE_CLEAR:
  		nvmf_ns_reservation_clear_all_registrants(ns);
  		if (num_hostid) {
  			nvmf_subsystem_gen_ctrlr_notification(ns->subsystem, ns,
  							      hostid_list,
  							      num_hostid,
  							      SPDK_NVME_RESERVATION_PREEMPTED);
  		}
  		break;
  	default:
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		update_sgroup = false;
  		goto exit;
  	}
  
  exit:
  	if (update_sgroup && ns->ptpl_activated) {
  		if (nvmf_ns_update_reservation_info(ns)) {
  			status = SPDK_NVME_SC_INTERNAL_DEVICE_ERROR;
  		}
  	}
  	req->rsp->nvme_cpl.status.sct = SPDK_NVME_SCT_GENERIC;
  	req->rsp->nvme_cpl.status.sc = status;
  	return update_sgroup;
  }
  
  static void
  nvmf_ns_reservation_report(struct spdk_nvmf_ns *ns,
  			   struct spdk_nvmf_ctrlr *ctrlr,
  			   struct spdk_nvmf_request *req)
  {
  	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
  	struct spdk_nvmf_subsystem *subsystem = ctrlr->subsys;
  	struct spdk_nvmf_ctrlr *ctrlr_tmp;
  	struct spdk_nvmf_registrant *reg, *tmp;
  	struct spdk_nvme_reservation_status_extended_data *status_data;
  	struct spdk_nvme_registered_ctrlr_extended_data *ctrlr_data;
  	uint8_t *payload;
  	uint32_t len, count = 0;
  	uint32_t regctl = 0;
  	uint8_t status = SPDK_NVME_SC_SUCCESS;
  
  	if (req->data == NULL) {
  		SPDK_ERRLOG("No data transfer specified for request. "
  			    " Unable to transfer back response.\n");
  		status = SPDK_NVME_SC_INVALID_FIELD;
  		goto exit;
  	}
  
  	/* NVMeoF uses Extended Data Structure */
  	if ((cmd->cdw11 & 0x00000001u) == 0) {
  		SPDK_ERRLOG("NVMeoF uses extended controller data structure, "
  			    "please set EDS bit in cdw11 and try again\n");
  		status = SPDK_NVME_SC_HOSTID_INCONSISTENT_FORMAT;
  		goto exit;
  	}
  
  	/* Get number of registerd controllers, one Host may have more than
  	 * one controller based on different ports.
  	 */
  	TAILQ_FOREACH(ctrlr_tmp, &subsystem->ctrlrs, link) {
  		reg = nvmf_ns_reservation_get_registrant(ns, &ctrlr_tmp->hostid);
  		if (reg) {
  			regctl++;
  		}
  	}
  
  	len = sizeof(*status_data) + sizeof(*ctrlr_data) * regctl;
  	payload = calloc(1, len);
  	if (!payload) {
  		status = SPDK_NVME_SC_INTERNAL_DEVICE_ERROR;
  		goto exit;
  	}
  
  	status_data = (struct spdk_nvme_reservation_status_extended_data *)payload;
  	status_data->data.gen = ns->gen;
  	status_data->data.rtype = ns->rtype;
  	status_data->data.regctl = regctl;
  	status_data->data.ptpls = ns->ptpl_activated;
  
  	TAILQ_FOREACH_SAFE(reg, &ns->registrants, link, tmp) {
  		assert(count <= regctl);
  		ctrlr_data = (struct spdk_nvme_registered_ctrlr_extended_data *)
  			     (payload + sizeof(*status_data) + sizeof(*ctrlr_data) * count);
  		/* Set to 0xffffh for dynamic controller */
  		ctrlr_data->cntlid = 0xffff;
  		ctrlr_data->rcsts.status = (ns->holder == reg) ? true : false;
  		ctrlr_data->rkey = reg->rkey;
  		spdk_uuid_copy((struct spdk_uuid *)ctrlr_data->hostid, &reg->hostid);
  		count++;
  	}
  
  	memcpy(req->data, payload, spdk_min(len, (cmd->cdw10 + 1) * sizeof(uint32_t)));
  	free(payload);
  
  exit:
  	req->rsp->nvme_cpl.status.sct = SPDK_NVME_SCT_GENERIC;
  	req->rsp->nvme_cpl.status.sc = status;
  	return;
  }
  
  static void
  spdk_nvmf_ns_reservation_complete(void *ctx)
  {
  	struct spdk_nvmf_request *req = ctx;
  
  	spdk_nvmf_request_complete(req);
  }
  
  static void
  _nvmf_ns_reservation_update_done(struct spdk_nvmf_subsystem *subsystem,
  				 void *cb_arg, int status)
  {
  	struct spdk_nvmf_request *req = (struct spdk_nvmf_request *)cb_arg;
  	struct spdk_nvmf_poll_group *group = req->qpair->group;
  
  	spdk_thread_send_msg(group->thread, spdk_nvmf_ns_reservation_complete, req);
  }
  
  void
  spdk_nvmf_ns_reservation_request(void *ctx)
  {
  	struct spdk_nvmf_request *req = (struct spdk_nvmf_request *)ctx;
  	struct spdk_nvme_cmd *cmd = &req->cmd->nvme_cmd;
  	struct spdk_nvmf_ctrlr *ctrlr = req->qpair->ctrlr;
  	struct subsystem_update_ns_ctx *update_ctx;
  	uint32_t nsid;
  	struct spdk_nvmf_ns *ns;
  	bool update_sgroup = false;
  
  	nsid = cmd->nsid;
  	ns = _spdk_nvmf_subsystem_get_ns(ctrlr->subsys, nsid);
  	assert(ns != NULL);
  
  	switch (cmd->opc) {
  	case SPDK_NVME_OPC_RESERVATION_REGISTER:
  		update_sgroup = nvmf_ns_reservation_register(ns, ctrlr, req);
  		break;
  	case SPDK_NVME_OPC_RESERVATION_ACQUIRE:
  		update_sgroup = nvmf_ns_reservation_acquire(ns, ctrlr, req);
  		break;
  	case SPDK_NVME_OPC_RESERVATION_RELEASE:
  		update_sgroup = nvmf_ns_reservation_release(ns, ctrlr, req);
  		break;
  	case SPDK_NVME_OPC_RESERVATION_REPORT:
  		nvmf_ns_reservation_report(ns, ctrlr, req);
  		break;
  	default:
  		break;
  	}
  
  	/* update reservation information to subsystem's poll group */
  	if (update_sgroup) {
  		update_ctx = calloc(1, sizeof(*update_ctx));
  		if (update_ctx == NULL) {
  			SPDK_ERRLOG("Can't alloc subsystem poll group update context\n");
  			goto update_done;
  		}
  		update_ctx->subsystem = ctrlr->subsys;
  		update_ctx->cb_fn = _nvmf_ns_reservation_update_done;
  		update_ctx->cb_arg = req;
  
  		spdk_nvmf_subsystem_update_ns(ctrlr->subsys, subsystem_update_ns_done, update_ctx);
  		return;
  	}
  
  update_done:
  	_nvmf_ns_reservation_update_done(ctrlr->subsys, (void *)req, 0);
  }
  