diff --git a/drivers/nvme/Kconfig b/drivers/nvme/Kconfig
index a39d943..b7c78a5 100644
--- a/drivers/nvme/Kconfig
+++ b/drivers/nvme/Kconfig
@@ -1 +1,2 @@
 source "drivers/nvme/host/Kconfig"
+source "drivers/nvme/target/Kconfig"
diff --git a/drivers/nvme/Makefile b/drivers/nvme/Makefile
index 9421e82..0096a7f 100644
--- a/drivers/nvme/Makefile
+++ b/drivers/nvme/Makefile
@@ -1,2 +1,3 @@
 
 obj-y		+= host/
+obj-y		+= target/
diff --git a/drivers/nvme/target/Kconfig b/drivers/nvme/target/Kconfig
new file mode 100644
index 0000000..acf0c07
--- /dev/null
+++ b/drivers/nvme/target/Kconfig
@@ -0,0 +1,16 @@
+
+config NVME_TARGET
+	tristate "NVMe Target support"
+	depends on BLOCK
+	depends on CONFIGFS_FS
+	help
+	  This enabled target side support for the NVMe protocol, that is
+	  it allows the Linux kernel to implement NVMe subsystems and
+	  controllers and export Linux block devices as NVMe namespaces.
+	  You need to select at least one of the transports below to make this
+	  functionality useful.
+
+	  To configure the NVMe target you probably want to use the nvmetcli
+	  tool from http://git.infradead.org/users/hch/nvmetcli.git.
+
+	  If unsure, say N.
diff --git a/drivers/nvme/target/Makefile b/drivers/nvme/target/Makefile
new file mode 100644
index 0000000..b4600b6
--- /dev/null
+++ b/drivers/nvme/target/Makefile
@@ -0,0 +1,5 @@
+
+obj-$(CONFIG_NVME_TARGET)		+= nvmet.o
+
+nvmet-y		+= core.o configfs.o admin-cmd.o io-cmd.o fabrics-cmd.o \
+			discovery.o
diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
new file mode 100644
index 0000000..240e323
--- /dev/null
+++ b/drivers/nvme/target/admin-cmd.c
@@ -0,0 +1,463 @@
+/*
+ * NVMe admin command implementation.
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/random.h>
+#include <generated/utsrelease.h>
+#include "nvmet.h"
+
+u32 nvmet_get_log_page_len(struct nvme_command *cmd)
+{
+	u32 len = le16_to_cpu(cmd->get_log_page.numdu);
+
+	len <<= 16;
+	len += le16_to_cpu(cmd->get_log_page.numdl);
+	/* NUMD is a 0's based value */
+	len += 1;
+	len *= sizeof(u32);
+
+	return len;
+}
+
+static void nvmet_execute_get_log_page(struct nvmet_req *req)
+{
+	size_t data_len = nvmet_get_log_page_len(req->cmd);
+	void *buf;
+	u16 status = 0;
+
+	buf = kzalloc(data_len, GFP_KERNEL);
+	if (!buf) {
+		status = NVME_SC_INTERNAL;
+		goto out;
+	}
+
+	switch (req->cmd->get_log_page.lid) {
+	case 0x01:
+		/*
+		 * We currently never set the More bit in the status field,
+		 * so all error log entries are invalid and can be zeroed out.
+		 * This is called a minum viable implementation (TM) of this
+		 * mandatory log page.
+		 */
+		break;
+	case 0x02:
+		/*
+		 * XXX: fill out actual smart log
+		 *
+		 * We might have a hard time coming up with useful values for
+		 * many of the fields, and even when we have useful data
+		 * available (e.g. units or commands read/written) those aren't
+		 * persistent over power loss.
+		 */
+		break;
+	case 0x03:
+		/*
+		 * We only support a single firmware slot which always is
+		 * active, so we can zero out the whole firmware slot log and
+		 * still claim to fully implement this mandatory log page.
+		 */
+		break;
+	default:
+		BUG();
+	}
+
+	status = nvmet_copy_to_sgl(req, 0, buf, data_len);
+
+	kfree(buf);
+out:
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	struct nvme_id_ctrl *id;
+	u64 serial;
+	u16 status = 0;
+
+	id = kzalloc(sizeof(*id), GFP_KERNEL);
+	if (!id) {
+		status = NVME_SC_INTERNAL;
+		goto out;
+	}
+
+	/* XXX: figure out how to assign real vendors IDs. */
+	id->vid = 0;
+	id->ssvid = 0;
+
+	/* generate a random serial number as our controllers are ephemeral: */
+	get_random_bytes(&serial, sizeof(serial));
+	memset(id->sn, ' ', sizeof(id->sn));
+	snprintf(id->sn, sizeof(id->sn), "%llx", serial);
+
+	memset(id->mn, ' ', sizeof(id->mn));
+	strncpy((char *)id->mn, "Linux", sizeof(id->mn));
+
+	memset(id->fr, ' ', sizeof(id->fr));
+	strncpy((char *)id->fr, UTS_RELEASE, sizeof(id->fr));
+
+	id->rab = 6;
+
+	/*
+	 * XXX: figure out how we can assign a IEEE OUI, but until then
+	 * the safest is to leave it as zeroes.
+	 */
+
+	/* we support multiple ports and multiples hosts: */
+	id->mic = (1 << 0) | (1 << 1);
+
+	/* no limit on data transfer sizes for now */
+	id->mdts = 0;
+	id->cntlid = cpu_to_le16(ctrl->cntlid);
+	id->ver = cpu_to_le32(ctrl->subsys->ver);
+
+	/* XXX: figure out what to do about RTD3R/RTD3 */
+	id->oaes = cpu_to_le32(1 << 8);
+	id->ctratt = cpu_to_le32(1 << 0);
+
+	id->oacs = 0;
+
+	/*
+	 * We don't really have a practical limit on the number of abort
+	 * comands.  But we don't do anything useful for abort either, so
+	 * no point in allowing more abort commands than the spec requires.
+	 */
+	id->acl = 3;
+
+	id->aerl = NVMET_ASYNC_EVENTS - 1;
+
+	/* first slot is read-only, only one slot supported */
+	id->frmw = (1 << 0) | (1 << 1);
+	id->lpa = (1 << 0) | (1 << 2);
+	id->elpe = NVMET_ERROR_LOG_SLOTS - 1;
+	id->npss = 0;
+
+	/* We support keep-alive timeout in granularity of seconds */
+	id->kas = cpu_to_le16(NVMET_KAS);
+
+	id->sqes = (0x6 << 4) | 0x6;
+	id->cqes = (0x4 << 4) | 0x4;
+
+	/* no enforcement soft-limit for maxcmd - pick arbitrary high value */
+	id->maxcmd = cpu_to_le16(NVMET_MAX_CMD);
+
+	id->nn = cpu_to_le32(ctrl->subsys->max_nsid);
+	id->oncs = cpu_to_le16(NVME_CTRL_ONCS_DSM);
+
+	/* XXX: don't report vwc if the underlying device is write through */
+	id->vwc = NVME_CTRL_VWC_PRESENT;
+
+	/*
+	 * We can't support atomic writes bigger than a LBA without support
+	 * from the backend device.
+	 */
+	id->awun = 0;
+	id->awupf = 0;
+
+	id->sgls = cpu_to_le32(1 << 0);	/* we always support SGLs */
+	if (ctrl->ops->has_keyed_sgls)
+		id->sgls |= cpu_to_le32(1 << 2);
+	if (ctrl->ops->sqe_inline_size)
+		id->sgls |= cpu_to_le32(1 << 20);
+
+	strcpy(id->subnqn, ctrl->subsys->subsysnqn);
+
+	/* Max command capsule size is sqe + single page of in-capsule data */
+	id->ioccsz = cpu_to_le32((sizeof(struct nvme_command) +
+				  ctrl->ops->sqe_inline_size) / 16);
+	/* Max response capsule size is cqe */
+	id->iorcsz = cpu_to_le32(sizeof(struct nvme_completion) / 16);
+
+	id->msdbd = ctrl->ops->msdbd;
+
+	/*
+	 * Meh, we don't really support any power state.  Fake up the same
+	 * values that qemu does.
+	 */
+	id->psd[0].max_power = cpu_to_le16(0x9c4);
+	id->psd[0].entry_lat = cpu_to_le32(0x10);
+	id->psd[0].exit_lat = cpu_to_le32(0x4);
+
+	status = nvmet_copy_to_sgl(req, 0, id, sizeof(*id));
+
+	kfree(id);
+out:
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_identify_ns(struct nvmet_req *req)
+{
+	struct nvmet_ns *ns;
+	struct nvme_id_ns *id;
+	u16 status = 0;
+
+	ns = nvmet_find_namespace(req->sq->ctrl, req->cmd->identify.nsid);
+	if (!ns) {
+		status = NVME_SC_INVALID_NS | NVME_SC_DNR;
+		goto out;
+	}
+
+	id = kzalloc(sizeof(*id), GFP_KERNEL);
+	if (!id) {
+		status = NVME_SC_INTERNAL;
+		goto out_put_ns;
+	}
+
+	/*
+	 * nuse = ncap = nsze isn't aways true, but we have no way to find
+	 * that out from the underlying device.
+	 */
+	id->ncap = id->nuse = id->nsze =
+		cpu_to_le64(ns->size >> ns->blksize_shift);
+
+	/*
+	 * We just provide a single LBA format that matches what the
+	 * underlying device reports.
+	 */
+	id->nlbaf = 0;
+	id->flbas = 0;
+
+	/*
+	 * Our namespace might always be shared.  Not just with other
+	 * controllers, but also with any other user of the block device.
+	 */
+	id->nmic = (1 << 0);
+
+	memcpy(&id->nguid, &ns->nguid, sizeof(uuid_le));
+
+	id->lbaf[0].ds = ns->blksize_shift;
+
+	status = nvmet_copy_to_sgl(req, 0, id, sizeof(*id));
+
+	kfree(id);
+out_put_ns:
+	nvmet_put_namespace(ns);
+out:
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_identify_nslist(struct nvmet_req *req)
+{
+	static const int buf_size = 4096;
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	struct nvmet_ns *ns;
+	u32 min_nsid = le32_to_cpu(req->cmd->identify.nsid);
+	__le32 *list;
+	u16 status = 0;
+	int i = 0;
+
+	list = kzalloc(buf_size, GFP_KERNEL);
+	if (!list) {
+		status = NVME_SC_INTERNAL;
+		goto out;
+	}
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link) {
+		if (ns->nsid <= min_nsid)
+			continue;
+		list[i++] = cpu_to_le32(ns->nsid);
+		if (i == buf_size / sizeof(__le32))
+			break;
+	}
+	rcu_read_unlock();
+
+	status = nvmet_copy_to_sgl(req, 0, list, buf_size);
+
+	kfree(list);
+out:
+	nvmet_req_complete(req, status);
+}
+
+/*
+ * A "mimimum viable" abort implementation: the command is mandatory in the
+ * spec, but we are not required to do any useful work.  We couldn't really
+ * do a useful abort, so don't bother even with waiting for the command
+ * to be exectuted and return immediately telling the command to abort
+ * wasn't found.
+ */
+static void nvmet_execute_abort(struct nvmet_req *req)
+{
+	nvmet_set_result(req, 1);
+	nvmet_req_complete(req, 0);
+}
+
+static void nvmet_execute_set_features(struct nvmet_req *req)
+{
+	struct nvmet_subsys *subsys = req->sq->ctrl->subsys;
+	u32 cdw10 = le32_to_cpu(req->cmd->common.cdw10[0]);
+	u64 val;
+	u16 status = 0;
+
+	switch (cdw10 & 0xf) {
+	case NVME_FEAT_NUM_QUEUES:
+		nvmet_set_result(req,
+			(subsys->max_qid - 1) | ((subsys->max_qid - 1) << 16));
+		break;
+	case NVME_FEAT_KATO:
+		val = le64_to_cpu(req->cmd->prop_set.value);
+		req->sq->ctrl->kato = (u32)DIV_ROUND_UP(val & 0xffff, 1000);
+		nvmet_set_result(req, req->sq->ctrl->kato);
+		break;
+	default:
+		status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+		break;
+	}
+
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_get_features(struct nvmet_req *req)
+{
+	struct nvmet_subsys *subsys = req->sq->ctrl->subsys;
+	u32 cdw10 = le32_to_cpu(req->cmd->common.cdw10[0]);
+	u16 status = 0;
+
+	switch (cdw10 & 0xf) {
+	/*
+	 * These features are mandatory in the spec, but we don't
+	 * have a useful way to implement them.  We'll eventually
+	 * need to come up with some fake values for these.
+	 */
+#if 0
+	case NVME_FEAT_ARBITRATION:
+		break;
+	case NVME_FEAT_POWER_MGMT:
+		break;
+	case NVME_FEAT_TEMP_THRESH:
+		break;
+	case NVME_FEAT_ERR_RECOVERY:
+		break;
+	case NVME_FEAT_IRQ_COALESCE:
+		break;
+	case NVME_FEAT_IRQ_CONFIG:
+		break;
+	case NVME_FEAT_WRITE_ATOMIC:
+		break;
+	case NVME_FEAT_ASYNC_EVENT:
+		break;
+#endif
+	case NVME_FEAT_VOLATILE_WC:
+		nvmet_set_result(req, 1);
+		break;
+	case NVME_FEAT_NUM_QUEUES:
+		nvmet_set_result(req,
+			(subsys->max_qid-1) | ((subsys->max_qid-1) << 16));
+		break;
+	case NVME_FEAT_KATO:
+		nvmet_set_result(req, req->sq->ctrl->kato * 1000);
+		break;
+	default:
+		status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+		break;
+	}
+
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_async_event(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+
+	mutex_lock(&ctrl->lock);
+	if (ctrl->nr_async_event_cmds >= NVMET_ASYNC_EVENTS) {
+		mutex_unlock(&ctrl->lock);
+		nvmet_req_complete(req, NVME_SC_ASYNC_LIMIT | NVME_SC_DNR);
+		return;
+	}
+	ctrl->async_event_cmds[ctrl->nr_async_event_cmds++] = req;
+	mutex_unlock(&ctrl->lock);
+
+	schedule_work(&ctrl->async_event_work);
+}
+
+static void nvmet_execute_keep_alive(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+
+	pr_debug("ctrl %d update keep-alive timer for %d secs\n",
+		ctrl->cntlid, ctrl->kato);
+
+	mod_delayed_work(system_wq, &ctrl->ka_work, ctrl->kato * HZ);
+	nvmet_req_complete(req, 0);
+}
+
+int nvmet_parse_admin_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	req->ns = NULL;
+
+	if (unlikely(!(req->sq->ctrl->cc & NVME_CC_ENABLE))) {
+		pr_err("nvmet: got admin cmd %d while CC.EN == 0\n",
+				cmd->common.opcode);
+		return NVME_SC_CMD_SEQ_ERROR | NVME_SC_DNR;
+	}
+	if (unlikely(!(req->sq->ctrl->csts & NVME_CSTS_RDY))) {
+		pr_err("nvmet: got admin cmd %d while CSTS.RDY == 0\n",
+				cmd->common.opcode);
+		return NVME_SC_CMD_SEQ_ERROR | NVME_SC_DNR;
+	}
+
+	switch (cmd->common.opcode) {
+	case nvme_admin_get_log_page:
+		req->data_len = nvmet_get_log_page_len(cmd);
+
+		switch (cmd->get_log_page.lid) {
+		case 0x01:
+		case 0x02:
+		case 0x03:
+			req->execute = nvmet_execute_get_log_page;
+			return 0;
+		}
+		break;
+	case nvme_admin_identify:
+		req->data_len = 4096;
+		switch (le32_to_cpu(cmd->identify.cns)) {
+		case 0x00:
+			req->execute = nvmet_execute_identify_ns;
+			return 0;
+		case 0x01:
+			req->execute = nvmet_execute_identify_ctrl;
+			return 0;
+		case 0x02:
+			req->execute = nvmet_execute_identify_nslist;
+			return 0;
+		}
+		break;
+	case nvme_admin_abort_cmd:
+		req->execute = nvmet_execute_abort;
+		req->data_len = 0;
+		return 0;
+	case nvme_admin_set_features:
+		req->execute = nvmet_execute_set_features;
+		req->data_len = 0;
+		return 0;
+	case nvme_admin_get_features:
+		req->execute = nvmet_execute_get_features;
+		req->data_len = 0;
+		return 0;
+	case nvme_admin_async_event:
+		req->execute = nvmet_execute_async_event;
+		req->data_len = 0;
+		return 0;
+	case nvme_admin_keep_alive:
+		req->execute = nvmet_execute_keep_alive;
+		req->data_len = 0;
+		return 0;
+	}
+
+	pr_err("nvmet: unhandled cmd %d\n", cmd->common.opcode);
+	return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+}
diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
new file mode 100644
index 0000000..aebe646
--- /dev/null
+++ b/drivers/nvme/target/configfs.c
@@ -0,0 +1,917 @@
+/*
+ * Configfs interface for the NVMe target.
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/ctype.h>
+
+#include "nvmet.h"
+
+static struct config_item_type nvmet_host_type;
+static struct config_item_type nvmet_subsys_type;
+
+/*
+ * nvmet_port Generic ConfigFS definitions.
+ * Used in any place in the ConfigFS tree that refers to an address.
+ */
+static ssize_t nvmet_addr_adrfam_show(struct config_item *item,
+		char *page)
+{
+	switch (to_nvmet_port(item)->disc_addr.adrfam) {
+	case NVMF_ADDR_FAMILY_IP4:
+		return sprintf(page, "ipv4\n");
+	case NVMF_ADDR_FAMILY_IP6:
+		return sprintf(page, "ipv6\n");
+	case NVMF_ADDR_FAMILY_IB:
+		return sprintf(page, "ib\n");
+	default:
+		return sprintf(page, "\n");
+	}
+}
+
+static ssize_t nvmet_addr_adrfam_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	if (port->enabled) {
+		pr_err("Cannot modify address while enabled\n");
+		pr_err("Disable the address before modifying\n");
+		return -EACCES;
+	}
+
+	if (sysfs_streq(page, "ipv4")) {
+		port->disc_addr.adrfam = NVMF_ADDR_FAMILY_IP4;
+	} else if (sysfs_streq(page, "ipv6")) {
+		port->disc_addr.adrfam = NVMF_ADDR_FAMILY_IP6;
+	} else if (sysfs_streq(page, "ib")) {
+		port->disc_addr.adrfam = NVMF_ADDR_FAMILY_IB;
+	} else {
+		pr_err("Invalid value '%s' for adrfam\n", page);
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+CONFIGFS_ATTR(nvmet_, addr_adrfam);
+
+static ssize_t nvmet_addr_portid_show(struct config_item *item,
+		char *page)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			le16_to_cpu(port->disc_addr.portid));
+}
+
+static ssize_t nvmet_addr_portid_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+	u16 portid = 0;
+
+	if (kstrtou16(page, 0, &portid)) {
+		pr_err("Invalid value '%s' for portid\n", page);
+		return -EINVAL;
+	}
+
+	if (port->enabled) {
+		pr_err("Cannot modify address while enabled\n");
+		pr_err("Disable the address before modifying\n");
+		return -EACCES;
+	}
+	port->disc_addr.portid = cpu_to_le16(portid);
+	return count;
+}
+
+CONFIGFS_ATTR(nvmet_, addr_portid);
+
+static ssize_t nvmet_addr_traddr_show(struct config_item *item,
+		char *page)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	return snprintf(page, PAGE_SIZE, "%s\n",
+			port->disc_addr.traddr);
+}
+
+static ssize_t nvmet_addr_traddr_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	if (count > NVMF_TRADDR_SIZE) {
+		pr_err("Invalid value '%s' for traddr\n", page);
+		return -EINVAL;
+	}
+
+	if (port->enabled) {
+		pr_err("Cannot modify address while enabled\n");
+		pr_err("Disable the address before modifying\n");
+		return -EACCES;
+	}
+	return snprintf(port->disc_addr.traddr,
+			sizeof(port->disc_addr.traddr), "%s", page);
+}
+
+CONFIGFS_ATTR(nvmet_, addr_traddr);
+
+static ssize_t nvmet_addr_treq_show(struct config_item *item,
+		char *page)
+{
+	switch (to_nvmet_port(item)->disc_addr.treq) {
+	case NVMF_TREQ_NOT_SPECIFIED:
+		return sprintf(page, "not specified\n");
+	case NVMF_TREQ_REQUIRED:
+		return sprintf(page, "required\n");
+	case NVMF_TREQ_NOT_REQUIRED:
+		return sprintf(page, "not required\n");
+	default:
+		return sprintf(page, "\n");
+	}
+}
+
+static ssize_t nvmet_addr_treq_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	if (port->enabled) {
+		pr_err("Cannot modify address while enabled\n");
+		pr_err("Disable the address before modifying\n");
+		return -EACCES;
+	}
+
+	if (sysfs_streq(page, "not specified")) {
+		port->disc_addr.treq = NVMF_TREQ_NOT_SPECIFIED;
+	} else if (sysfs_streq(page, "required")) {
+		port->disc_addr.treq = NVMF_TREQ_REQUIRED;
+	} else if (sysfs_streq(page, "not required")) {
+		port->disc_addr.treq = NVMF_TREQ_NOT_REQUIRED;
+	} else {
+		pr_err("Invalid value '%s' for treq\n", page);
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+CONFIGFS_ATTR(nvmet_, addr_treq);
+
+static ssize_t nvmet_addr_trsvcid_show(struct config_item *item,
+		char *page)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	return snprintf(page, PAGE_SIZE, "%s\n",
+			port->disc_addr.trsvcid);
+}
+
+static ssize_t nvmet_addr_trsvcid_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	if (count > NVMF_TRSVCID_SIZE) {
+		pr_err("Invalid value '%s' for trsvcid\n", page);
+		return -EINVAL;
+	}
+	if (port->enabled) {
+		pr_err("Cannot modify address while enabled\n");
+		pr_err("Disable the address before modifying\n");
+		return -EACCES;
+	}
+	return snprintf(port->disc_addr.trsvcid,
+			sizeof(port->disc_addr.trsvcid), "%s", page);
+}
+
+CONFIGFS_ATTR(nvmet_, addr_trsvcid);
+
+static ssize_t nvmet_addr_trtype_show(struct config_item *item,
+		char *page)
+{
+	switch (to_nvmet_port(item)->disc_addr.trtype) {
+	case NVMF_TRTYPE_RDMA:
+		return sprintf(page, "rdma\n");
+	case NVMF_TRTYPE_LOOP:
+		return sprintf(page, "loop\n");
+	default:
+		return sprintf(page, "\n");
+	}
+}
+
+static void nvmet_port_init_tsas_rdma(struct nvmet_port *port)
+{
+	port->disc_addr.trtype = NVMF_TRTYPE_RDMA;
+	memset(&port->disc_addr.tsas.rdma, 0, NVMF_TSAS_SIZE);
+	port->disc_addr.tsas.rdma.qptype = NVMF_RDMA_QPTYPE_CONNECTED;
+	port->disc_addr.tsas.rdma.prtype = NVMF_RDMA_PRTYPE_NOT_SPECIFIED;
+	port->disc_addr.tsas.rdma.cms = NVMF_RDMA_CMS_RDMA_CM;
+}
+
+static void nvmet_port_init_tsas_loop(struct nvmet_port *port)
+{
+	port->disc_addr.trtype = NVMF_TRTYPE_LOOP;
+	memset(&port->disc_addr.tsas, 0, NVMF_TSAS_SIZE);
+}
+
+static ssize_t nvmet_addr_trtype_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	if (port->enabled) {
+		pr_err("Cannot modify address while enabled\n");
+		pr_err("Disable the address before modifying\n");
+		return -EACCES;
+	}
+
+	if (sysfs_streq(page, "rdma")) {
+		nvmet_port_init_tsas_rdma(port);
+	} else if (sysfs_streq(page, "loop")) {
+		nvmet_port_init_tsas_loop(port);
+	} else {
+		pr_err("Invalid value '%s' for trtype\n", page);
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+CONFIGFS_ATTR(nvmet_, addr_trtype);
+
+/*
+ * Namespace structures & file operation functions below
+ */
+static ssize_t nvmet_ns_device_path_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%s\n", to_nvmet_ns(item)->device_path);
+}
+
+static ssize_t nvmet_ns_device_path_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	struct nvmet_subsys *subsys = ns->subsys;
+	int ret;
+
+	mutex_lock(&subsys->lock);
+	ret = -EBUSY;
+	if (nvmet_ns_enabled(ns))
+		goto out_unlock;
+
+	kfree(ns->device_path);
+
+	ret = -ENOMEM;
+	ns->device_path = kstrdup(page, GFP_KERNEL);
+	if (!ns->device_path)
+		goto out_unlock;
+
+	mutex_unlock(&subsys->lock);
+	return count;
+
+out_unlock:
+	mutex_unlock(&subsys->lock);
+	return ret;
+}
+
+CONFIGFS_ATTR(nvmet_ns_, device_path);
+
+static ssize_t nvmet_ns_device_nguid_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%pUb\n", &to_nvmet_ns(item)->nguid);
+}
+
+static ssize_t nvmet_ns_device_nguid_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	struct nvmet_subsys *subsys = ns->subsys;
+	u8 nguid[16];
+	const char *p = page;
+	int i;
+	int ret = 0;
+
+	mutex_lock(&subsys->lock);
+	if (nvmet_ns_enabled(ns)) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
+	for (i = 0; i < 16; i++) {
+		if (p + 2 > page + count) {
+			ret = -EINVAL;
+			goto out_unlock;
+		}
+		if (!isxdigit(p[0]) || !isxdigit(p[1])) {
+			ret = -EINVAL;
+			goto out_unlock;
+		}
+
+		nguid[i] = (hex_to_bin(p[0]) << 4) | hex_to_bin(p[1]);
+		p += 2;
+
+		if (*p == '-' || *p == ':')
+			p++;
+	}
+
+	memcpy(&ns->nguid, nguid, sizeof(nguid));
+out_unlock:
+	mutex_unlock(&subsys->lock);
+	return ret ? ret : count;
+}
+
+CONFIGFS_ATTR(nvmet_ns_, device_nguid);
+
+static ssize_t nvmet_ns_enable_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%d\n", nvmet_ns_enabled(to_nvmet_ns(item)));
+}
+
+static ssize_t nvmet_ns_enable_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+	bool enable;
+	int ret = 0;
+
+	if (strtobool(page, &enable))
+		return -EINVAL;
+
+	if (enable)
+		ret = nvmet_ns_enable(ns);
+	else
+		nvmet_ns_disable(ns);
+
+	return ret ? ret : count;
+}
+
+CONFIGFS_ATTR(nvmet_ns_, enable);
+
+static struct configfs_attribute *nvmet_ns_attrs[] = {
+	&nvmet_ns_attr_device_path,
+	&nvmet_ns_attr_device_nguid,
+	&nvmet_ns_attr_enable,
+	NULL,
+};
+
+static void nvmet_ns_release(struct config_item *item)
+{
+	struct nvmet_ns *ns = to_nvmet_ns(item);
+
+	nvmet_ns_free(ns);
+}
+
+static struct configfs_item_operations nvmet_ns_item_ops = {
+	.release		= nvmet_ns_release,
+};
+
+static struct config_item_type nvmet_ns_type = {
+	.ct_item_ops		= &nvmet_ns_item_ops,
+	.ct_attrs		= nvmet_ns_attrs,
+	.ct_owner		= THIS_MODULE,
+};
+
+static struct config_group *nvmet_ns_make(struct config_group *group,
+		const char *name)
+{
+	struct nvmet_subsys *subsys = namespaces_to_subsys(&group->cg_item);
+	struct nvmet_ns *ns;
+	int ret;
+	u32 nsid;
+
+	ret = kstrtou32(name, 0, &nsid);
+	if (ret)
+		goto out;
+
+	ret = -EINVAL;
+	if (nsid == 0 || nsid == 0xffffffff)
+		goto out;
+
+	ret = -ENOMEM;
+	ns = nvmet_ns_alloc(subsys, nsid);
+	if (!ns)
+		goto out;
+	config_group_init_type_name(&ns->group, name, &nvmet_ns_type);
+
+	pr_info("adding nsid %d to subsystem %s\n", nsid, subsys->subsysnqn);
+
+	return &ns->group;
+out:
+	return ERR_PTR(ret);
+}
+
+static struct configfs_group_operations nvmet_namespaces_group_ops = {
+	.make_group		= nvmet_ns_make,
+};
+
+static struct config_item_type nvmet_namespaces_type = {
+	.ct_group_ops		= &nvmet_namespaces_group_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static int nvmet_port_subsys_allow_link(struct config_item *parent,
+		struct config_item *target)
+{
+	struct nvmet_port *port = to_nvmet_port(parent->ci_parent);
+	struct nvmet_subsys *subsys;
+	struct nvmet_subsys_link *link, *p;
+	int ret;
+
+	if (target->ci_type != &nvmet_subsys_type) {
+		pr_err("can only link subsystems into the subsystems dir.!\n");
+		return -EINVAL;
+	}
+	subsys = to_subsys(target);
+	link = kmalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		return -ENOMEM;
+	link->subsys = subsys;
+
+	down_write(&nvmet_config_sem);
+	ret = -EEXIST;
+	list_for_each_entry(p, &port->subsystems, entry) {
+		if (p->subsys == subsys)
+			goto out_free_link;
+	}
+
+	if (list_empty(&port->subsystems)) {
+		ret = nvmet_enable_port(port);
+		if (ret)
+			goto out_free_link;
+	}
+
+	list_add_tail(&link->entry, &port->subsystems);
+	nvmet_genctr++;
+	up_write(&nvmet_config_sem);
+	return 0;
+
+out_free_link:
+	up_write(&nvmet_config_sem);
+	kfree(link);
+	return ret;
+}
+
+static int nvmet_port_subsys_drop_link(struct config_item *parent,
+		struct config_item *target)
+{
+	struct nvmet_port *port = to_nvmet_port(parent->ci_parent);
+	struct nvmet_subsys *subsys = to_subsys(target);
+	struct nvmet_subsys_link *p;
+
+	down_write(&nvmet_config_sem);
+	list_for_each_entry(p, &port->subsystems, entry) {
+		if (p->subsys == subsys)
+			goto found;
+	}
+	up_write(&nvmet_config_sem);
+	return -EINVAL;
+
+found:
+	list_del(&p->entry);
+	nvmet_genctr++;
+	if (list_empty(&port->subsystems))
+		nvmet_disable_port(port);
+	up_write(&nvmet_config_sem);
+	kfree(p);
+	return 0;
+}
+
+static struct configfs_item_operations nvmet_port_subsys_item_ops = {
+	.allow_link		= nvmet_port_subsys_allow_link,
+	.drop_link		= nvmet_port_subsys_drop_link,
+};
+
+static struct config_item_type nvmet_port_subsys_type = {
+	.ct_item_ops		= &nvmet_port_subsys_item_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static int nvmet_allowed_hosts_allow_link(struct config_item *parent,
+		struct config_item *target)
+{
+	struct nvmet_subsys *subsys = to_subsys(parent->ci_parent);
+	struct nvmet_host *host;
+	struct nvmet_host_link *link, *p;
+	int ret;
+
+	if (target->ci_type != &nvmet_host_type) {
+		pr_err("can only link hosts into the allowed_hosts directory!\n");
+		return -EINVAL;
+	}
+
+	host = to_host(target);
+	link = kmalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		return -ENOMEM;
+	link->host = host;
+
+	down_write(&nvmet_config_sem);
+	ret = -EINVAL;
+	if (subsys->allow_any_host) {
+		pr_err("can't add hosts when allow_any_host is set!\n");
+		goto out_free_link;
+	}
+
+	ret = -EEXIST;
+	list_for_each_entry(p, &subsys->hosts, entry) {
+		if (!strcmp(nvmet_host_name(p->host), nvmet_host_name(host)))
+			goto out_free_link;
+	}
+	list_add_tail(&link->entry, &subsys->hosts);
+	nvmet_genctr++;
+	up_write(&nvmet_config_sem);
+	return 0;
+out_free_link:
+	up_write(&nvmet_config_sem);
+	kfree(link);
+	return ret;
+}
+
+static int nvmet_allowed_hosts_drop_link(struct config_item *parent,
+		struct config_item *target)
+{
+	struct nvmet_subsys *subsys = to_subsys(parent->ci_parent);
+	struct nvmet_host *host = to_host(target);
+	struct nvmet_host_link *p;
+
+	down_write(&nvmet_config_sem);
+	list_for_each_entry(p, &subsys->hosts, entry) {
+		if (!strcmp(nvmet_host_name(p->host), nvmet_host_name(host)))
+			goto found;
+	}
+	up_write(&nvmet_config_sem);
+	return -EINVAL;
+
+found:
+	list_del(&p->entry);
+	nvmet_genctr++;
+	up_write(&nvmet_config_sem);
+	kfree(p);
+	return 0;
+}
+
+static struct configfs_item_operations nvmet_allowed_hosts_item_ops = {
+	.allow_link		= nvmet_allowed_hosts_allow_link,
+	.drop_link		= nvmet_allowed_hosts_drop_link,
+};
+
+static struct config_item_type nvmet_allowed_hosts_type = {
+	.ct_item_ops		= &nvmet_allowed_hosts_item_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static ssize_t nvmet_subsys_attr_allow_any_host_show(struct config_item *item,
+		char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+		to_subsys(item)->allow_any_host);
+}
+
+static ssize_t nvmet_subsys_attr_allow_any_host_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+	bool allow_any_host;
+	int ret = 0;
+
+	if (strtobool(page, &allow_any_host))
+		return -EINVAL;
+
+	down_write(&nvmet_config_sem);
+	if (allow_any_host && !list_empty(&subsys->hosts)) {
+		pr_err("Can't set allow_any_host when explicit hosts are set!\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	subsys->allow_any_host = allow_any_host;
+out_unlock:
+	up_write(&nvmet_config_sem);
+	return ret ? ret : count;
+}
+
+CONFIGFS_ATTR(nvmet_subsys_, attr_allow_any_host);
+
+static struct configfs_attribute *nvmet_subsys_attrs[] = {
+	&nvmet_subsys_attr_attr_allow_any_host,
+	NULL,
+};
+
+/*
+ * Subsystem structures & folder operation functions below
+ */
+static void nvmet_subsys_release(struct config_item *item)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+
+	nvmet_subsys_put(subsys);
+}
+
+static struct configfs_item_operations nvmet_subsys_item_ops = {
+	.release		= nvmet_subsys_release,
+};
+
+static struct config_item_type nvmet_subsys_type = {
+	.ct_item_ops		= &nvmet_subsys_item_ops,
+	.ct_attrs		= nvmet_subsys_attrs,
+	.ct_owner		= THIS_MODULE,
+};
+
+static struct config_group *nvmet_subsys_make(struct config_group *group,
+		const char *name)
+{
+	struct nvmet_subsys *subsys;
+
+	if (sysfs_streq(name, NVME_DISC_SUBSYS_NAME)) {
+		pr_err("can't create discovery subsystem through configfs\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	subsys = nvmet_subsys_alloc(name, NVME_NQN_NVME);
+	if (!subsys)
+		return ERR_PTR(-ENOMEM);
+
+	config_group_init_type_name(&subsys->group, name, &nvmet_subsys_type);
+
+	config_group_init_type_name(&subsys->namespaces_group,
+			"namespaces", &nvmet_namespaces_type);
+	configfs_add_default_group(&subsys->namespaces_group, &subsys->group);
+
+	config_group_init_type_name(&subsys->allowed_hosts_group,
+			"allowed_hosts", &nvmet_allowed_hosts_type);
+	configfs_add_default_group(&subsys->allowed_hosts_group,
+			&subsys->group);
+
+	return &subsys->group;
+}
+
+static struct configfs_group_operations nvmet_subsystems_group_ops = {
+	.make_group		= nvmet_subsys_make,
+};
+
+static struct config_item_type nvmet_subsystems_type = {
+	.ct_group_ops		= &nvmet_subsystems_group_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static ssize_t nvmet_referral_enable_show(struct config_item *item,
+		char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n", to_nvmet_port(item)->enabled);
+}
+
+static ssize_t nvmet_referral_enable_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_port *parent = to_nvmet_port(item->ci_parent->ci_parent);
+	struct nvmet_port *port = to_nvmet_port(item);
+	bool enable;
+
+	if (strtobool(page, &enable))
+		goto inval;
+
+	if (enable)
+		nvmet_referral_enable(parent, port);
+	else
+		nvmet_referral_disable(port);
+
+	return count;
+inval:
+	pr_err("Invalid value '%s' for enable\n", page);
+	return -EINVAL;
+}
+
+CONFIGFS_ATTR(nvmet_referral_, enable);
+
+/*
+ * Discovery Service subsystem definitions
+ */
+static struct configfs_attribute *nvmet_referral_attrs[] = {
+	&nvmet_attr_addr_adrfam,
+	&nvmet_attr_addr_portid,
+	&nvmet_attr_addr_treq,
+	&nvmet_attr_addr_traddr,
+	&nvmet_attr_addr_trsvcid,
+	&nvmet_attr_addr_trtype,
+	&nvmet_referral_attr_enable,
+	NULL,
+};
+
+static void nvmet_referral_release(struct config_item *item)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	nvmet_referral_disable(port);
+	kfree(port);
+}
+
+static struct configfs_item_operations nvmet_referral_item_ops = {
+	.release	= nvmet_referral_release,
+};
+
+static struct config_item_type nvmet_referral_type = {
+	.ct_owner	= THIS_MODULE,
+	.ct_attrs	= nvmet_referral_attrs,
+	.ct_item_ops	= &nvmet_referral_item_ops,
+};
+
+static struct config_group *nvmet_referral_make(
+		struct config_group *group, const char *name)
+{
+	struct nvmet_port *port;
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (IS_ERR(port))
+		return ERR_CAST(port);
+
+	INIT_LIST_HEAD(&port->entry);
+	config_group_init_type_name(&port->group, name, &nvmet_referral_type);
+
+	return &port->group;
+}
+
+static struct configfs_group_operations nvmet_referral_group_ops = {
+	.make_group		= nvmet_referral_make,
+};
+
+static struct config_item_type nvmet_referrals_type = {
+	.ct_owner	= THIS_MODULE,
+	.ct_group_ops	= &nvmet_referral_group_ops,
+};
+
+/*
+ * Ports definitions.
+ */
+static void nvmet_port_release(struct config_item *item)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+
+	kfree(port);
+}
+
+static struct configfs_attribute *nvmet_port_attrs[] = {
+	&nvmet_attr_addr_adrfam,
+	&nvmet_attr_addr_treq,
+	&nvmet_attr_addr_traddr,
+	&nvmet_attr_addr_trsvcid,
+	&nvmet_attr_addr_trtype,
+	NULL,
+};
+
+static struct configfs_item_operations nvmet_port_item_ops = {
+	.release		= nvmet_port_release,
+};
+
+static struct config_item_type nvmet_port_type = {
+	.ct_attrs		= nvmet_port_attrs,
+	.ct_item_ops		= &nvmet_port_item_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static struct config_group *nvmet_ports_make(struct config_group *group,
+		const char *name)
+{
+	struct nvmet_port *port;
+	u16 portid;
+
+	if (kstrtou16(name, 0, &portid))
+		return ERR_PTR(-EINVAL);
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (IS_ERR(port))
+		return ERR_CAST(port);
+
+	INIT_LIST_HEAD(&port->entry);
+	INIT_LIST_HEAD(&port->subsystems);
+	INIT_LIST_HEAD(&port->referrals);
+
+	port->disc_addr.portid = cpu_to_le16(portid);
+	config_group_init_type_name(&port->group, name, &nvmet_port_type);
+
+	config_group_init_type_name(&port->subsys_group,
+			"subsystems", &nvmet_port_subsys_type);
+	configfs_add_default_group(&port->subsys_group, &port->group);
+
+	config_group_init_type_name(&port->referrals_group,
+			"referrals", &nvmet_referrals_type);
+	configfs_add_default_group(&port->referrals_group, &port->group);
+
+	return &port->group;
+}
+
+static struct configfs_group_operations nvmet_ports_group_ops = {
+	.make_group		= nvmet_ports_make,
+};
+
+static struct config_item_type nvmet_ports_type = {
+	.ct_group_ops		= &nvmet_ports_group_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static struct config_group nvmet_subsystems_group;
+static struct config_group nvmet_ports_group;
+
+static void nvmet_host_release(struct config_item *item)
+{
+	struct nvmet_host *host = to_host(item);
+
+	kfree(host);
+}
+
+static struct configfs_item_operations nvmet_host_item_ops = {
+	.release		= nvmet_host_release,
+};
+
+static struct config_item_type nvmet_host_type = {
+	.ct_item_ops		= &nvmet_host_item_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static struct config_group *nvmet_hosts_make_group(struct config_group *group,
+		const char *name)
+{
+	struct nvmet_host *host;
+
+	host = kzalloc(sizeof(*host), GFP_KERNEL);
+	if (!host)
+		return ERR_PTR(-ENOMEM);
+
+	config_group_init_type_name(&host->group, name, &nvmet_host_type);
+
+	return &host->group;
+}
+
+static struct configfs_group_operations nvmet_hosts_group_ops = {
+	.make_group		= nvmet_hosts_make_group,
+};
+
+static struct config_item_type nvmet_hosts_type = {
+	.ct_group_ops		= &nvmet_hosts_group_ops,
+	.ct_owner		= THIS_MODULE,
+};
+
+static struct config_group nvmet_hosts_group;
+
+static struct config_item_type nvmet_root_type = {
+	.ct_owner		= THIS_MODULE,
+};
+
+static struct configfs_subsystem nvmet_configfs_subsystem = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf	= "nvmet",
+			.ci_type	= &nvmet_root_type,
+		},
+	},
+};
+
+int __init nvmet_init_configfs(void)
+{
+	int ret;
+
+	config_group_init(&nvmet_configfs_subsystem.su_group);
+	mutex_init(&nvmet_configfs_subsystem.su_mutex);
+
+	config_group_init_type_name(&nvmet_subsystems_group,
+			"subsystems", &nvmet_subsystems_type);
+	configfs_add_default_group(&nvmet_subsystems_group,
+			&nvmet_configfs_subsystem.su_group);
+
+	config_group_init_type_name(&nvmet_ports_group,
+			"ports", &nvmet_ports_type);
+	configfs_add_default_group(&nvmet_ports_group,
+			&nvmet_configfs_subsystem.su_group);
+
+	config_group_init_type_name(&nvmet_hosts_group,
+			"hosts", &nvmet_hosts_type);
+	configfs_add_default_group(&nvmet_hosts_group,
+			&nvmet_configfs_subsystem.su_group);
+
+	ret = configfs_register_subsystem(&nvmet_configfs_subsystem);
+	if (ret) {
+		pr_err("configfs_register_subsystem: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+void __exit nvmet_exit_configfs(void)
+{
+	configfs_unregister_subsystem(&nvmet_configfs_subsystem);
+}
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
new file mode 100644
index 0000000..e0b3f01
--- /dev/null
+++ b/drivers/nvme/target/core.c
@@ -0,0 +1,964 @@
+/*
+ * Common code for the NVMe target.
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include "nvmet.h"
+
+static struct nvmet_fabrics_ops *nvmet_transports[NVMF_TRTYPE_MAX];
+
+/*
+ * This read/write semaphore is used to synchronize access to configuration
+ * information on a target system that will result in discovery log page
+ * information change for at least one host.
+ * The full list of resources to protected by this semaphore is:
+ *
+ *  - subsystems list
+ *  - per-subsystem allowed hosts list
+ *  - allow_any_host subsystem attribute
+ *  - nvmet_genctr
+ *  - the nvmet_transports array
+ *
+ * When updating any of those lists/structures write lock should be obtained,
+ * while when reading (popolating discovery log page or checking host-subsystem
+ * link) read lock is obtained to allow concurrent reads.
+ */
+DECLARE_RWSEM(nvmet_config_sem);
+
+static struct nvmet_subsys *nvmet_find_get_subsys(struct nvmet_port *port,
+		const char *subsysnqn);
+
+u16 nvmet_copy_to_sgl(struct nvmet_req *req, off_t off, const void *buf,
+		size_t len)
+{
+	if (sg_pcopy_from_buffer(req->sg, req->sg_cnt, buf, len, off) != len)
+		return NVME_SC_SGL_INVALID_DATA | NVME_SC_DNR;
+	return 0;
+}
+
+u16 nvmet_copy_from_sgl(struct nvmet_req *req, off_t off, void *buf, size_t len)
+{
+	if (sg_pcopy_to_buffer(req->sg, req->sg_cnt, buf, len, off) != len)
+		return NVME_SC_SGL_INVALID_DATA | NVME_SC_DNR;
+	return 0;
+}
+
+static u32 nvmet_async_event_result(struct nvmet_async_event *aen)
+{
+	return aen->event_type | (aen->event_info << 8) | (aen->log_page << 16);
+}
+
+static void nvmet_async_events_free(struct nvmet_ctrl *ctrl)
+{
+	struct nvmet_req *req;
+
+	while (1) {
+		mutex_lock(&ctrl->lock);
+		if (!ctrl->nr_async_event_cmds) {
+			mutex_unlock(&ctrl->lock);
+			return;
+		}
+
+		req = ctrl->async_event_cmds[--ctrl->nr_async_event_cmds];
+		mutex_unlock(&ctrl->lock);
+		nvmet_req_complete(req, NVME_SC_INTERNAL | NVME_SC_DNR);
+	}
+}
+
+static void nvmet_async_event_work(struct work_struct *work)
+{
+	struct nvmet_ctrl *ctrl =
+		container_of(work, struct nvmet_ctrl, async_event_work);
+	struct nvmet_async_event *aen;
+	struct nvmet_req *req;
+
+	while (1) {
+		mutex_lock(&ctrl->lock);
+		aen = list_first_entry_or_null(&ctrl->async_events,
+				struct nvmet_async_event, entry);
+		if (!aen || !ctrl->nr_async_event_cmds) {
+			mutex_unlock(&ctrl->lock);
+			return;
+		}
+
+		req = ctrl->async_event_cmds[--ctrl->nr_async_event_cmds];
+		nvmet_set_result(req, nvmet_async_event_result(aen));
+
+		list_del(&aen->entry);
+		kfree(aen);
+
+		mutex_unlock(&ctrl->lock);
+		nvmet_req_complete(req, 0);
+	}
+}
+
+static void nvmet_add_async_event(struct nvmet_ctrl *ctrl, u8 event_type,
+		u8 event_info, u8 log_page)
+{
+	struct nvmet_async_event *aen;
+
+	aen = kmalloc(sizeof(*aen), GFP_KERNEL);
+	if (!aen)
+		return;
+
+	aen->event_type = event_type;
+	aen->event_info = event_info;
+	aen->log_page = log_page;
+
+	mutex_lock(&ctrl->lock);
+	list_add_tail(&aen->entry, &ctrl->async_events);
+	mutex_unlock(&ctrl->lock);
+
+	schedule_work(&ctrl->async_event_work);
+}
+
+int nvmet_register_transport(struct nvmet_fabrics_ops *ops)
+{
+	int ret = 0;
+
+	down_write(&nvmet_config_sem);
+	if (nvmet_transports[ops->type])
+		ret = -EINVAL;
+	else
+		nvmet_transports[ops->type] = ops;
+	up_write(&nvmet_config_sem);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nvmet_register_transport);
+
+void nvmet_unregister_transport(struct nvmet_fabrics_ops *ops)
+{
+	down_write(&nvmet_config_sem);
+	nvmet_transports[ops->type] = NULL;
+	up_write(&nvmet_config_sem);
+}
+EXPORT_SYMBOL_GPL(nvmet_unregister_transport);
+
+int nvmet_enable_port(struct nvmet_port *port)
+{
+	struct nvmet_fabrics_ops *ops;
+	int ret;
+
+	lockdep_assert_held(&nvmet_config_sem);
+
+	ops = nvmet_transports[port->disc_addr.trtype];
+	if (!ops) {
+		up_write(&nvmet_config_sem);
+		request_module("nvmet-transport-%d", port->disc_addr.trtype);
+		down_write(&nvmet_config_sem);
+		ops = nvmet_transports[port->disc_addr.trtype];
+		if (!ops) {
+			pr_err("transport type %d not supported\n",
+				port->disc_addr.trtype);
+			return -EINVAL;
+		}
+	}
+
+	if (!try_module_get(ops->owner))
+		return -EINVAL;
+
+	ret = ops->add_port(port);
+	if (ret) {
+		module_put(ops->owner);
+		return ret;
+	}
+
+	port->enabled = true;
+	return 0;
+}
+
+void nvmet_disable_port(struct nvmet_port *port)
+{
+	struct nvmet_fabrics_ops *ops;
+
+	lockdep_assert_held(&nvmet_config_sem);
+
+	port->enabled = false;
+
+	ops = nvmet_transports[port->disc_addr.trtype];
+	ops->remove_port(port);
+	module_put(ops->owner);
+}
+
+static void nvmet_keep_alive_timer(struct work_struct *work)
+{
+	struct nvmet_ctrl *ctrl = container_of(to_delayed_work(work),
+			struct nvmet_ctrl, ka_work);
+
+	pr_err("ctrl %d keep-alive timer (%d seconds) expired!\n",
+		ctrl->cntlid, ctrl->kato);
+
+	ctrl->ops->delete_ctrl(ctrl);
+}
+
+static void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl)
+{
+	pr_debug("ctrl %d start keep-alive timer for %d secs\n",
+		ctrl->cntlid, ctrl->kato);
+
+	INIT_DELAYED_WORK(&ctrl->ka_work, nvmet_keep_alive_timer);
+	schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
+}
+
+static void nvmet_stop_keep_alive_timer(struct nvmet_ctrl *ctrl)
+{
+	pr_debug("ctrl %d stop keep-alive\n", ctrl->cntlid);
+
+	cancel_delayed_work_sync(&ctrl->ka_work);
+}
+
+static struct nvmet_ns *__nvmet_find_namespace(struct nvmet_ctrl *ctrl,
+		__le32 nsid)
+{
+	struct nvmet_ns *ns;
+
+	list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link) {
+		if (ns->nsid == le32_to_cpu(nsid))
+			return ns;
+	}
+
+	return NULL;
+}
+
+struct nvmet_ns *nvmet_find_namespace(struct nvmet_ctrl *ctrl, __le32 nsid)
+{
+	struct nvmet_ns *ns;
+
+	rcu_read_lock();
+	ns = __nvmet_find_namespace(ctrl, nsid);
+	if (ns)
+		percpu_ref_get(&ns->ref);
+	rcu_read_unlock();
+
+	return ns;
+}
+
+static void nvmet_destroy_namespace(struct percpu_ref *ref)
+{
+	struct nvmet_ns *ns = container_of(ref, struct nvmet_ns, ref);
+
+	complete(&ns->disable_done);
+}
+
+void nvmet_put_namespace(struct nvmet_ns *ns)
+{
+	percpu_ref_put(&ns->ref);
+}
+
+int nvmet_ns_enable(struct nvmet_ns *ns)
+{
+	struct nvmet_subsys *subsys = ns->subsys;
+	struct nvmet_ctrl *ctrl;
+	int ret = 0;
+
+	mutex_lock(&subsys->lock);
+	if (!list_empty(&ns->dev_link))
+		goto out_unlock;
+
+	ns->bdev = blkdev_get_by_path(ns->device_path, FMODE_READ | FMODE_WRITE,
+			NULL);
+	if (IS_ERR(ns->bdev)) {
+		pr_err("nvmet: failed to open block device %s: (%ld)\n",
+			ns->device_path, PTR_ERR(ns->bdev));
+		ret = PTR_ERR(ns->bdev);
+		ns->bdev = NULL;
+		goto out_unlock;
+	}
+
+	ns->size = i_size_read(ns->bdev->bd_inode);
+	ns->blksize_shift = blksize_bits(bdev_logical_block_size(ns->bdev));
+
+	ret = percpu_ref_init(&ns->ref, nvmet_destroy_namespace,
+				0, GFP_KERNEL);
+	if (ret)
+		goto out_blkdev_put;
+
+	if (ns->nsid > subsys->max_nsid)
+		subsys->max_nsid = ns->nsid;
+
+	/*
+	 * The namespaces list needs to be sorted to simplify the implementation
+	 * of the Identify Namepace List subcommand.
+	 */
+	if (list_empty(&subsys->namespaces)) {
+		list_add_tail_rcu(&ns->dev_link, &subsys->namespaces);
+	} else {
+		struct nvmet_ns *old;
+
+		list_for_each_entry_rcu(old, &subsys->namespaces, dev_link) {
+			BUG_ON(ns->nsid == old->nsid);
+			if (ns->nsid < old->nsid)
+				break;
+		}
+
+		list_add_tail_rcu(&ns->dev_link, &old->dev_link);
+	}
+
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)
+		nvmet_add_async_event(ctrl, NVME_AER_TYPE_NOTICE, 0, 0);
+
+	ret = 0;
+out_unlock:
+	mutex_unlock(&subsys->lock);
+	return ret;
+out_blkdev_put:
+	blkdev_put(ns->bdev, FMODE_WRITE|FMODE_READ);
+	ns->bdev = NULL;
+	goto out_unlock;
+}
+
+void nvmet_ns_disable(struct nvmet_ns *ns)
+{
+	struct nvmet_subsys *subsys = ns->subsys;
+	struct nvmet_ctrl *ctrl;
+
+	mutex_lock(&subsys->lock);
+	if (list_empty(&ns->dev_link)) {
+		mutex_unlock(&subsys->lock);
+		return;
+	}
+	list_del_init(&ns->dev_link);
+	mutex_unlock(&subsys->lock);
+
+	/*
+	 * Now that we removed the namespaces from the lookup list, we
+	 * can kill the per_cpu ref and wait for any remaining references
+	 * to be dropped, as well as a RCU grace period for anyone only
+	 * using the namepace under rcu_read_lock().  Note that we can't
+	 * use call_rcu here as we need to ensure the namespaces have
+	 * been fully destroyed before unloading the module.
+	 */
+	percpu_ref_kill(&ns->ref);
+	synchronize_rcu();
+	wait_for_completion(&ns->disable_done);
+	percpu_ref_exit(&ns->ref);
+
+	mutex_lock(&subsys->lock);
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)
+		nvmet_add_async_event(ctrl, NVME_AER_TYPE_NOTICE, 0, 0);
+
+	if (ns->bdev)
+		blkdev_put(ns->bdev, FMODE_WRITE|FMODE_READ);
+	mutex_unlock(&subsys->lock);
+}
+
+void nvmet_ns_free(struct nvmet_ns *ns)
+{
+	nvmet_ns_disable(ns);
+
+	kfree(ns->device_path);
+	kfree(ns);
+}
+
+struct nvmet_ns *nvmet_ns_alloc(struct nvmet_subsys *subsys, u32 nsid)
+{
+	struct nvmet_ns *ns;
+
+	ns = kzalloc(sizeof(*ns), GFP_KERNEL);
+	if (!ns)
+		return NULL;
+
+	INIT_LIST_HEAD(&ns->dev_link);
+	init_completion(&ns->disable_done);
+
+	ns->nsid = nsid;
+	ns->subsys = subsys;
+
+	return ns;
+}
+
+static void __nvmet_req_complete(struct nvmet_req *req, u16 status)
+{
+	if (status)
+		nvmet_set_status(req, status);
+
+	/* XXX: need to fill in something useful for sq_head */
+	req->rsp->sq_head = 0;
+	if (likely(req->sq)) /* may happen during early failure */
+		req->rsp->sq_id = cpu_to_le16(req->sq->qid);
+	req->rsp->command_id = req->cmd->common.command_id;
+
+	if (req->ns)
+		nvmet_put_namespace(req->ns);
+	req->ops->queue_response(req);
+}
+
+void nvmet_req_complete(struct nvmet_req *req, u16 status)
+{
+	__nvmet_req_complete(req, status);
+	percpu_ref_put(&req->sq->ref);
+}
+EXPORT_SYMBOL_GPL(nvmet_req_complete);
+
+void nvmet_cq_setup(struct nvmet_ctrl *ctrl, struct nvmet_cq *cq,
+		u16 qid, u16 size)
+{
+	cq->qid = qid;
+	cq->size = size;
+
+	ctrl->cqs[qid] = cq;
+}
+
+void nvmet_sq_setup(struct nvmet_ctrl *ctrl, struct nvmet_sq *sq,
+		u16 qid, u16 size)
+{
+	sq->qid = qid;
+	sq->size = size;
+
+	ctrl->sqs[qid] = sq;
+}
+
+void nvmet_sq_destroy(struct nvmet_sq *sq)
+{
+	/*
+	 * If this is the admin queue, complete all AERs so that our
+	 * queue doesn't have outstanding requests on it.
+	 */
+	if (sq->ctrl && sq->ctrl->sqs && sq->ctrl->sqs[0] == sq)
+		nvmet_async_events_free(sq->ctrl);
+	percpu_ref_kill(&sq->ref);
+	wait_for_completion(&sq->free_done);
+	percpu_ref_exit(&sq->ref);
+
+	if (sq->ctrl) {
+		nvmet_ctrl_put(sq->ctrl);
+		sq->ctrl = NULL; /* allows reusing the queue later */
+	}
+}
+EXPORT_SYMBOL_GPL(nvmet_sq_destroy);
+
+static void nvmet_sq_free(struct percpu_ref *ref)
+{
+	struct nvmet_sq *sq = container_of(ref, struct nvmet_sq, ref);
+
+	complete(&sq->free_done);
+}
+
+int nvmet_sq_init(struct nvmet_sq *sq)
+{
+	int ret;
+
+	ret = percpu_ref_init(&sq->ref, nvmet_sq_free, 0, GFP_KERNEL);
+	if (ret) {
+		pr_err("percpu_ref init failed!\n");
+		return ret;
+	}
+	init_completion(&sq->free_done);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvmet_sq_init);
+
+bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
+		struct nvmet_sq *sq, struct nvmet_fabrics_ops *ops)
+{
+	u8 flags = req->cmd->common.flags;
+	u16 status;
+
+	req->cq = cq;
+	req->sq = sq;
+	req->ops = ops;
+	req->sg = NULL;
+	req->sg_cnt = 0;
+	req->rsp->status = 0;
+
+	/* no support for fused commands yet */
+	if (unlikely(flags & (NVME_CMD_FUSE_FIRST | NVME_CMD_FUSE_SECOND))) {
+		status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+		goto fail;
+	}
+
+	/* either variant of SGLs is fine, as we don't support metadata */
+	if (unlikely((flags & NVME_CMD_SGL_ALL) != NVME_CMD_SGL_METABUF &&
+		     (flags & NVME_CMD_SGL_ALL) != NVME_CMD_SGL_METASEG)) {
+		status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+		goto fail;
+	}
+
+	if (unlikely(!req->sq->ctrl))
+		/* will return an error for any Non-connect command: */
+		status = nvmet_parse_connect_cmd(req);
+	else if (likely(req->sq->qid != 0))
+		status = nvmet_parse_io_cmd(req);
+	else if (req->cmd->common.opcode == nvme_fabrics_command)
+		status = nvmet_parse_fabrics_cmd(req);
+	else if (req->sq->ctrl->subsys->type == NVME_NQN_DISC)
+		status = nvmet_parse_discovery_cmd(req);
+	else
+		status = nvmet_parse_admin_cmd(req);
+
+	if (status)
+		goto fail;
+
+	if (unlikely(!percpu_ref_tryget_live(&sq->ref))) {
+		status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+		goto fail;
+	}
+
+	return true;
+
+fail:
+	__nvmet_req_complete(req, status);
+	return false;
+}
+EXPORT_SYMBOL_GPL(nvmet_req_init);
+
+static inline bool nvmet_cc_en(u32 cc)
+{
+	return cc & 0x1;
+}
+
+static inline u8 nvmet_cc_css(u32 cc)
+{
+	return (cc >> 4) & 0x7;
+}
+
+static inline u8 nvmet_cc_mps(u32 cc)
+{
+	return (cc >> 7) & 0xf;
+}
+
+static inline u8 nvmet_cc_ams(u32 cc)
+{
+	return (cc >> 11) & 0x7;
+}
+
+static inline u8 nvmet_cc_shn(u32 cc)
+{
+	return (cc >> 14) & 0x3;
+}
+
+static inline u8 nvmet_cc_iosqes(u32 cc)
+{
+	return (cc >> 16) & 0xf;
+}
+
+static inline u8 nvmet_cc_iocqes(u32 cc)
+{
+	return (cc >> 20) & 0xf;
+}
+
+static void nvmet_start_ctrl(struct nvmet_ctrl *ctrl)
+{
+	lockdep_assert_held(&ctrl->lock);
+
+	if (nvmet_cc_iosqes(ctrl->cc) != NVME_NVM_IOSQES ||
+	    nvmet_cc_iocqes(ctrl->cc) != NVME_NVM_IOCQES ||
+	    nvmet_cc_mps(ctrl->cc) != 0 ||
+	    nvmet_cc_ams(ctrl->cc) != 0 ||
+	    nvmet_cc_css(ctrl->cc) != 0) {
+		ctrl->csts = NVME_CSTS_CFS;
+		return;
+	}
+
+	ctrl->csts = NVME_CSTS_RDY;
+}
+
+static void nvmet_clear_ctrl(struct nvmet_ctrl *ctrl)
+{
+	lockdep_assert_held(&ctrl->lock);
+
+	/* XXX: tear down queues? */
+	ctrl->csts &= ~NVME_CSTS_RDY;
+	ctrl->cc = 0;
+}
+
+void nvmet_update_cc(struct nvmet_ctrl *ctrl, u32 new)
+{
+	u32 old;
+
+	mutex_lock(&ctrl->lock);
+	old = ctrl->cc;
+	ctrl->cc = new;
+
+	if (nvmet_cc_en(new) && !nvmet_cc_en(old))
+		nvmet_start_ctrl(ctrl);
+	if (!nvmet_cc_en(new) && nvmet_cc_en(old))
+		nvmet_clear_ctrl(ctrl);
+	if (nvmet_cc_shn(new) && !nvmet_cc_shn(old)) {
+		nvmet_clear_ctrl(ctrl);
+		ctrl->csts |= NVME_CSTS_SHST_CMPLT;
+	}
+	if (!nvmet_cc_shn(new) && nvmet_cc_shn(old))
+		ctrl->csts &= ~NVME_CSTS_SHST_CMPLT;
+	mutex_unlock(&ctrl->lock);
+}
+
+static void nvmet_init_cap(struct nvmet_ctrl *ctrl)
+{
+	/* command sets supported: NVMe command set: */
+	ctrl->cap = (1ULL << 37);
+	/* CC.EN timeout in 500msec units: */
+	ctrl->cap |= (15ULL << 24);
+	/* maximum queue entries supported: */
+	ctrl->cap |= NVMET_QUEUE_SIZE - 1;
+}
+
+u16 nvmet_ctrl_find_get(const char *subsysnqn, const char *hostnqn, u16 cntlid,
+		struct nvmet_req *req, struct nvmet_ctrl **ret)
+{
+	struct nvmet_subsys *subsys;
+	struct nvmet_ctrl *ctrl;
+	u16 status = 0;
+
+	subsys = nvmet_find_get_subsys(req->port, subsysnqn);
+	if (!subsys) {
+		pr_warn("connect request for invalid subsystem %s!\n",
+			subsysnqn);
+		req->rsp->result = IPO_IATTR_CONNECT_DATA(subsysnqn);
+		return NVME_SC_CONNECT_INVALID_PARAM | NVME_SC_DNR;
+	}
+
+	mutex_lock(&subsys->lock);
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry) {
+		if (ctrl->cntlid == cntlid) {
+			if (strncmp(hostnqn, ctrl->hostnqn, NVMF_NQN_SIZE)) {
+				pr_warn("hostnqn mismatch.\n");
+				continue;
+			}
+			if (!kref_get_unless_zero(&ctrl->ref))
+				continue;
+
+			*ret = ctrl;
+			goto out;
+		}
+	}
+
+	pr_warn("could not find controller %d for subsys %s / host %s\n",
+		cntlid, subsysnqn, hostnqn);
+	req->rsp->result = IPO_IATTR_CONNECT_DATA(cntlid);
+	status = NVME_SC_CONNECT_INVALID_PARAM | NVME_SC_DNR;
+
+out:
+	mutex_unlock(&subsys->lock);
+	nvmet_subsys_put(subsys);
+	return status;
+}
+
+static bool __nvmet_host_allowed(struct nvmet_subsys *subsys,
+		const char *hostnqn)
+{
+	struct nvmet_host_link *p;
+
+	if (subsys->allow_any_host)
+		return true;
+
+	list_for_each_entry(p, &subsys->hosts, entry) {
+		if (!strcmp(nvmet_host_name(p->host), hostnqn))
+			return true;
+	}
+
+	return false;
+}
+
+static bool nvmet_host_discovery_allowed(struct nvmet_req *req,
+		const char *hostnqn)
+{
+	struct nvmet_subsys_link *s;
+
+	list_for_each_entry(s, &req->port->subsystems, entry) {
+		if (__nvmet_host_allowed(s->subsys, hostnqn))
+			return true;
+	}
+
+	return false;
+}
+
+bool nvmet_host_allowed(struct nvmet_req *req, struct nvmet_subsys *subsys,
+		const char *hostnqn)
+{
+	lockdep_assert_held(&nvmet_config_sem);
+
+	if (subsys->type == NVME_NQN_DISC)
+		return nvmet_host_discovery_allowed(req, hostnqn);
+	else
+		return __nvmet_host_allowed(subsys, hostnqn);
+}
+
+u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
+		struct nvmet_req *req, u32 kato, struct nvmet_ctrl **ctrlp)
+{
+	struct nvmet_subsys *subsys;
+	struct nvmet_ctrl *ctrl;
+	int ret;
+	u16 status;
+
+	status = NVME_SC_CONNECT_INVALID_PARAM | NVME_SC_DNR;
+	subsys = nvmet_find_get_subsys(req->port, subsysnqn);
+	if (!subsys) {
+		pr_warn("connect request for invalid subsystem %s!\n",
+			subsysnqn);
+		req->rsp->result = IPO_IATTR_CONNECT_DATA(subsysnqn);
+		goto out;
+	}
+
+	status = NVME_SC_CONNECT_INVALID_PARAM | NVME_SC_DNR;
+	down_read(&nvmet_config_sem);
+	if (!nvmet_host_allowed(req, subsys, hostnqn)) {
+		pr_info("connect by host %s for subsystem %s not allowed\n",
+			hostnqn, subsysnqn);
+		req->rsp->result = IPO_IATTR_CONNECT_DATA(hostnqn);
+		up_read(&nvmet_config_sem);
+		goto out_put_subsystem;
+	}
+	up_read(&nvmet_config_sem);
+
+	status = NVME_SC_INTERNAL;
+	ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
+	if (!ctrl)
+		goto out_put_subsystem;
+	mutex_init(&ctrl->lock);
+
+	nvmet_init_cap(ctrl);
+
+	INIT_WORK(&ctrl->async_event_work, nvmet_async_event_work);
+	INIT_LIST_HEAD(&ctrl->async_events);
+
+	memcpy(ctrl->subsysnqn, subsysnqn, NVMF_NQN_SIZE);
+	memcpy(ctrl->hostnqn, hostnqn, NVMF_NQN_SIZE);
+
+	kref_init(&ctrl->ref);
+	ctrl->subsys = subsys;
+
+	ctrl->cqs = kcalloc(subsys->max_qid + 1,
+			sizeof(struct nvmet_cq *),
+			GFP_KERNEL);
+	if (!ctrl->cqs)
+		goto out_free_ctrl;
+
+	ctrl->sqs = kcalloc(subsys->max_qid + 1,
+			sizeof(struct nvmet_sq *),
+			GFP_KERNEL);
+	if (!ctrl->sqs)
+		goto out_free_cqs;
+
+	ret = ida_simple_get(&subsys->cntlid_ida,
+			     NVME_CNTLID_MIN, NVME_CNTLID_MAX,
+			     GFP_KERNEL);
+	if (ret < 0) {
+		status = NVME_SC_CONNECT_CTRL_BUSY | NVME_SC_DNR;
+		goto out_free_sqs;
+	}
+	ctrl->cntlid = ret;
+
+	ctrl->ops = req->ops;
+	if (ctrl->subsys->type == NVME_NQN_DISC) {
+		/* Don't accept keep-alive timeout for discovery controllers */
+		if (kato) {
+			status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+			goto out_free_sqs;
+		}
+
+		/*
+		 * Discovery controllers use some arbitrary high value in order
+		 * to cleanup stale discovery sessions
+		 *
+		 * From the latest base diff RC:
+		 * "The Keep Alive command is not supported by
+		 * Discovery controllers. A transport may specify a
+		 * fixed Discovery controller activity timeout value
+		 * (e.g., 2 minutes).  If no commands are received
+		 * by a Discovery controller within that time
+		 * period, the controller may perform the
+		 * actions for Keep Alive Timer expiration".
+		 */
+		ctrl->kato = NVMET_DISC_KATO;
+	} else {
+		/* keep-alive timeout in seconds */
+		ctrl->kato = DIV_ROUND_UP(kato, 1000);
+	}
+	nvmet_start_keep_alive_timer(ctrl);
+
+	mutex_lock(&subsys->lock);
+	list_add_tail(&ctrl->subsys_entry, &subsys->ctrls);
+	mutex_unlock(&subsys->lock);
+
+	*ctrlp = ctrl;
+	return 0;
+
+out_free_sqs:
+	kfree(ctrl->sqs);
+out_free_cqs:
+	kfree(ctrl->cqs);
+out_free_ctrl:
+	kfree(ctrl);
+out_put_subsystem:
+	nvmet_subsys_put(subsys);
+out:
+	return status;
+}
+
+static void nvmet_ctrl_free(struct kref *ref)
+{
+	struct nvmet_ctrl *ctrl = container_of(ref, struct nvmet_ctrl, ref);
+	struct nvmet_subsys *subsys = ctrl->subsys;
+
+	nvmet_stop_keep_alive_timer(ctrl);
+
+	mutex_lock(&subsys->lock);
+	list_del(&ctrl->subsys_entry);
+	mutex_unlock(&subsys->lock);
+
+	ida_simple_remove(&subsys->cntlid_ida, ctrl->cntlid);
+	nvmet_subsys_put(subsys);
+
+	kfree(ctrl->sqs);
+	kfree(ctrl->cqs);
+	kfree(ctrl);
+}
+
+void nvmet_ctrl_put(struct nvmet_ctrl *ctrl)
+{
+	kref_put(&ctrl->ref, nvmet_ctrl_free);
+}
+
+static void nvmet_fatal_error_handler(struct work_struct *work)
+{
+	struct nvmet_ctrl *ctrl =
+			container_of(work, struct nvmet_ctrl, fatal_err_work);
+
+	pr_err("ctrl %d fatal error occurred!\n", ctrl->cntlid);
+	ctrl->ops->delete_ctrl(ctrl);
+}
+
+void nvmet_ctrl_fatal_error(struct nvmet_ctrl *ctrl)
+{
+	ctrl->csts |= NVME_CSTS_CFS;
+	INIT_WORK(&ctrl->fatal_err_work, nvmet_fatal_error_handler);
+	schedule_work(&ctrl->fatal_err_work);
+}
+EXPORT_SYMBOL_GPL(nvmet_ctrl_fatal_error);
+
+static struct nvmet_subsys *nvmet_find_get_subsys(struct nvmet_port *port,
+		const char *subsysnqn)
+{
+	struct nvmet_subsys_link *p;
+
+	if (!port)
+		return NULL;
+
+	if (!strncmp(NVME_DISC_SUBSYS_NAME, subsysnqn,
+			NVMF_NQN_SIZE)) {
+		if (!kref_get_unless_zero(&nvmet_disc_subsys->ref))
+			return NULL;
+		return nvmet_disc_subsys;
+	}
+
+	down_read(&nvmet_config_sem);
+	list_for_each_entry(p, &port->subsystems, entry) {
+		if (!strncmp(p->subsys->subsysnqn, subsysnqn,
+				NVMF_NQN_SIZE)) {
+			if (!kref_get_unless_zero(&p->subsys->ref))
+				break;
+			up_read(&nvmet_config_sem);
+			return p->subsys;
+		}
+	}
+	up_read(&nvmet_config_sem);
+	return NULL;
+}
+
+struct nvmet_subsys *nvmet_subsys_alloc(const char *subsysnqn,
+		enum nvme_subsys_type type)
+{
+	struct nvmet_subsys *subsys;
+
+	subsys = kzalloc(sizeof(*subsys), GFP_KERNEL);
+	if (!subsys)
+		return NULL;
+
+	subsys->ver = (1 << 16) | (2 << 8) | 1; /* NVMe 1.2.1 */
+
+	switch (type) {
+	case NVME_NQN_NVME:
+		subsys->max_qid = NVMET_NR_QUEUES;
+		break;
+	case NVME_NQN_DISC:
+		subsys->max_qid = 0;
+		break;
+	default:
+		pr_err("%s: Unknown Subsystem type - %d\n", __func__, type);
+		kfree(subsys);
+		return NULL;
+	}
+	subsys->type = type;
+	subsys->subsysnqn = kstrndup(subsysnqn, NVMF_NQN_SIZE,
+			GFP_KERNEL);
+	if (IS_ERR(subsys->subsysnqn)) {
+		kfree(subsys);
+		return NULL;
+	}
+
+	kref_init(&subsys->ref);
+
+	mutex_init(&subsys->lock);
+	INIT_LIST_HEAD(&subsys->namespaces);
+	INIT_LIST_HEAD(&subsys->ctrls);
+
+	ida_init(&subsys->cntlid_ida);
+
+	INIT_LIST_HEAD(&subsys->hosts);
+
+	return subsys;
+}
+
+static void nvmet_subsys_free(struct kref *ref)
+{
+	struct nvmet_subsys *subsys =
+		container_of(ref, struct nvmet_subsys, ref);
+
+	WARN_ON_ONCE(!list_empty(&subsys->namespaces));
+
+	ida_destroy(&subsys->cntlid_ida);
+	kfree(subsys->subsysnqn);
+	kfree(subsys);
+}
+
+void nvmet_subsys_put(struct nvmet_subsys *subsys)
+{
+	kref_put(&subsys->ref, nvmet_subsys_free);
+}
+
+static int __init nvmet_init(void)
+{
+	int error;
+
+	error = nvmet_init_discovery();
+	if (error)
+		goto out;
+
+	error = nvmet_init_configfs();
+	if (error)
+		goto out_exit_discovery;
+	return 0;
+
+out_exit_discovery:
+	nvmet_exit_discovery();
+out:
+	return error;
+}
+
+static void __exit nvmet_exit(void)
+{
+	nvmet_exit_configfs();
+	nvmet_exit_discovery();
+
+	BUILD_BUG_ON(sizeof(struct nvmf_disc_rsp_page_entry) != 1024);
+	BUILD_BUG_ON(sizeof(struct nvmf_disc_rsp_page_hdr) != 1024);
+}
+
+module_init(nvmet_init);
+module_exit(nvmet_exit);
+
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/nvme/target/discovery.c b/drivers/nvme/target/discovery.c
new file mode 100644
index 0000000..6f65646
--- /dev/null
+++ b/drivers/nvme/target/discovery.c
@@ -0,0 +1,221 @@
+/*
+ * Discovery service for the NVMe over Fabrics target.
+ * Copyright (C) 2016 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/slab.h>
+#include <generated/utsrelease.h>
+#include "nvmet.h"
+
+struct nvmet_subsys *nvmet_disc_subsys;
+
+u64 nvmet_genctr;
+
+void nvmet_referral_enable(struct nvmet_port *parent, struct nvmet_port *port)
+{
+	down_write(&nvmet_config_sem);
+	if (list_empty(&port->entry)) {
+		list_add_tail(&port->entry, &parent->referrals);
+		port->enabled = true;
+		nvmet_genctr++;
+	}
+	up_write(&nvmet_config_sem);
+}
+
+void nvmet_referral_disable(struct nvmet_port *port)
+{
+	down_write(&nvmet_config_sem);
+	if (!list_empty(&port->entry)) {
+		port->enabled = false;
+		list_del_init(&port->entry);
+		nvmet_genctr++;
+	}
+	up_write(&nvmet_config_sem);
+}
+
+static void nvmet_format_discovery_entry(struct nvmf_disc_rsp_page_hdr *hdr,
+		struct nvmet_port *port, char *subsys_nqn, u8 type, u32 numrec)
+{
+	struct nvmf_disc_rsp_page_entry *e = &hdr->entries[numrec];
+
+	e->trtype = port->disc_addr.trtype;
+	e->adrfam = port->disc_addr.adrfam;
+	e->treq = port->disc_addr.treq;
+	e->portid = port->disc_addr.portid;
+	/* we support only dynamic controllers */
+	e->cntlid = cpu_to_le16(NVME_CNTLID_DYNAMIC);
+	e->asqsz = cpu_to_le16(NVMF_AQ_DEPTH);
+	e->nqntype = type;
+	memcpy(e->trsvcid, port->disc_addr.trsvcid, NVMF_TRSVCID_SIZE);
+	memcpy(e->traddr, port->disc_addr.traddr, NVMF_TRADDR_SIZE);
+	memcpy(e->tsas.common, port->disc_addr.tsas.common, NVMF_TSAS_SIZE);
+	memcpy(e->subnqn, subsys_nqn, NVMF_NQN_SIZE);
+}
+
+static void nvmet_execute_get_disc_log_page(struct nvmet_req *req)
+{
+	const int entry_size = sizeof(struct nvmf_disc_rsp_page_entry);
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	struct nvmf_disc_rsp_page_hdr *hdr;
+	size_t data_len = nvmet_get_log_page_len(req->cmd);
+	size_t alloc_len = max(data_len, sizeof(*hdr));
+	int residual_len = data_len - sizeof(*hdr);
+	struct nvmet_subsys_link *p;
+	struct nvmet_port *r;
+	u32 numrec = 0;
+	u16 status = 0;
+
+	/*
+	 * Make sure we're passing at least a buffer of response header size.
+	 * If host provided data len is less than the header size, only the
+	 * number of bytes requested by host will be sent to host.
+	 */
+	hdr = kzalloc(alloc_len, GFP_KERNEL);
+	if (!hdr) {
+		status = NVME_SC_INTERNAL;
+		goto out;
+	}
+
+	down_read(&nvmet_config_sem);
+	list_for_each_entry(p, &req->port->subsystems, entry) {
+		if (!nvmet_host_allowed(req, p->subsys, ctrl->hostnqn))
+			continue;
+		if (residual_len >= entry_size) {
+			nvmet_format_discovery_entry(hdr, req->port,
+					p->subsys->subsysnqn,
+					NVME_NQN_NVME, numrec);
+			residual_len -= entry_size;
+		}
+		numrec++;
+	}
+
+	list_for_each_entry(r, &req->port->referrals, entry) {
+		if (residual_len >= entry_size) {
+			nvmet_format_discovery_entry(hdr, r,
+					NVME_DISC_SUBSYS_NAME,
+					NVME_NQN_DISC, numrec);
+			residual_len -= entry_size;
+		}
+		numrec++;
+	}
+
+	hdr->genctr = cpu_to_le64(nvmet_genctr);
+	hdr->numrec = cpu_to_le64(numrec);
+	hdr->recfmt = cpu_to_le16(0);
+
+	up_read(&nvmet_config_sem);
+
+	status = nvmet_copy_to_sgl(req, 0, hdr, data_len);
+	kfree(hdr);
+out:
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_identify_disc_ctrl(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	struct nvme_id_ctrl *id;
+	u16 status = 0;
+
+	id = kzalloc(sizeof(*id), GFP_KERNEL);
+	if (!id) {
+		status = NVME_SC_INTERNAL;
+		goto out;
+	}
+
+	memset(id->fr, ' ', sizeof(id->fr));
+	strncpy((char *)id->fr, UTS_RELEASE, sizeof(id->fr));
+
+	/* no limit on data transfer sizes for now */
+	id->mdts = 0;
+	id->cntlid = cpu_to_le16(ctrl->cntlid);
+	id->ver = cpu_to_le32(ctrl->subsys->ver);
+	id->lpa = (1 << 2);
+
+	/* no enforcement soft-limit for maxcmd - pick arbitrary high value */
+	id->maxcmd = cpu_to_le16(NVMET_MAX_CMD);
+
+	id->sgls = cpu_to_le32(1 << 0);	/* we always support SGLs */
+	if (ctrl->ops->has_keyed_sgls)
+		id->sgls |= cpu_to_le32(1 << 2);
+	if (ctrl->ops->sqe_inline_size)
+		id->sgls |= cpu_to_le32(1 << 20);
+
+	strcpy(id->subnqn, ctrl->subsys->subsysnqn);
+
+	status = nvmet_copy_to_sgl(req, 0, id, sizeof(*id));
+
+	kfree(id);
+out:
+	nvmet_req_complete(req, status);
+}
+
+int nvmet_parse_discovery_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	req->ns = NULL;
+
+	if (unlikely(!(req->sq->ctrl->csts & NVME_CSTS_RDY))) {
+		pr_err("nvmet: got cmd %d while not ready\n",
+				cmd->common.opcode);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+
+	switch (cmd->common.opcode) {
+	case nvme_admin_get_log_page:
+		req->data_len = nvmet_get_log_page_len(cmd);
+
+		switch (cmd->get_log_page.lid) {
+		case NVME_LOG_DISC:
+			req->execute = nvmet_execute_get_disc_log_page;
+			return 0;
+		default:
+			pr_err("nvmet: unsupported get_log_page lid %d\n",
+				cmd->get_log_page.lid);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+		}
+	case nvme_admin_identify:
+		req->data_len = 4096;
+		switch (le32_to_cpu(cmd->identify.cns)) {
+		case 0x01:
+			req->execute =
+				nvmet_execute_identify_disc_ctrl;
+			return 0;
+		default:
+			pr_err("nvmet: unsupported identify cns %d\n",
+				le32_to_cpu(cmd->identify.cns));
+			return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+		}
+	default:
+		pr_err("nvmet: unsupported cmd %d\n",
+				cmd->common.opcode);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+
+	pr_err("nvmet: unhandled cmd %d\n", cmd->common.opcode);
+	return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+}
+
+int __init nvmet_init_discovery(void)
+{
+	nvmet_disc_subsys =
+		nvmet_subsys_alloc(NVME_DISC_SUBSYS_NAME, NVME_NQN_DISC);
+	if (!nvmet_disc_subsys)
+		return -ENOMEM;
+	return 0;
+}
+
+void nvmet_exit_discovery(void)
+{
+	nvmet_subsys_put(nvmet_disc_subsys);
+}
diff --git a/drivers/nvme/target/fabrics-cmd.c b/drivers/nvme/target/fabrics-cmd.c
new file mode 100644
index 0000000..9a97ae6
--- /dev/null
+++ b/drivers/nvme/target/fabrics-cmd.c
@@ -0,0 +1,240 @@
+/*
+ * NVMe Fabrics command implementation.
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/blkdev.h>
+#include "nvmet.h"
+
+static void nvmet_execute_prop_set(struct nvmet_req *req)
+{
+	u16 status = 0;
+
+	if (!(req->cmd->prop_set.attrib & 1)) {
+		u64 val = le64_to_cpu(req->cmd->prop_set.value);
+
+		switch (le32_to_cpu(req->cmd->prop_set.offset)) {
+		case NVME_REG_CC:
+			nvmet_update_cc(req->sq->ctrl, val);
+			break;
+		default:
+			status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+			break;
+		}
+	} else {
+		status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+	}
+
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_prop_get(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	u16 status = 0;
+	u64 val = 0;
+
+	if (req->cmd->prop_get.attrib & 1) {
+		switch (le32_to_cpu(req->cmd->prop_get.offset)) {
+		case NVME_REG_CAP:
+			val = ctrl->cap;
+			break;
+		default:
+			status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+			break;
+		}
+	} else {
+		switch (le32_to_cpu(req->cmd->prop_get.offset)) {
+		case NVME_REG_VS:
+			val = ctrl->subsys->ver;
+			break;
+		case NVME_REG_CC:
+			val = ctrl->cc;
+			break;
+		case NVME_REG_CSTS:
+			val = ctrl->csts;
+			break;
+		default:
+			status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
+			break;
+		}
+	}
+
+	req->rsp->result64 = cpu_to_le64(val);
+	nvmet_req_complete(req, status);
+}
+
+int nvmet_parse_fabrics_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	req->ns = NULL;
+
+	switch (cmd->fabrics.fctype) {
+	case nvme_fabrics_type_property_set:
+		req->data_len = 0;
+		req->execute = nvmet_execute_prop_set;
+		break;
+	case nvme_fabrics_type_property_get:
+		req->data_len = 0;
+		req->execute = nvmet_execute_prop_get;
+		break;
+	default:
+		pr_err("received unknown capsule type 0x%x\n",
+			cmd->fabrics.fctype);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+
+	return 0;
+}
+
+static u16 nvmet_install_queue(struct nvmet_ctrl *ctrl, struct nvmet_req *req)
+{
+	struct nvmf_connect_command *c = &req->cmd->connect;
+	u16 qid = le16_to_cpu(c->qid);
+	u16 sqsize = le16_to_cpu(c->sqsize);
+	struct nvmet_ctrl *old;
+
+	old = cmpxchg(&req->sq->ctrl, NULL, ctrl);
+	if (old) {
+		pr_warn("queue already connected!\n");
+		return NVME_SC_CONNECT_CTRL_BUSY | NVME_SC_DNR;
+	}
+
+	nvmet_cq_setup(ctrl, req->cq, qid, sqsize);
+	nvmet_sq_setup(ctrl, req->sq, qid, sqsize);
+	return 0;
+}
+
+static void nvmet_execute_admin_connect(struct nvmet_req *req)
+{
+	struct nvmf_connect_command *c = &req->cmd->connect;
+	struct nvmf_connect_data *d;
+	struct nvmet_ctrl *ctrl = NULL;
+	u16 status = 0;
+
+	d = kmap(sg_page(req->sg)) + req->sg->offset;
+
+	/* zero out initial completion result, assign values as needed */
+	req->rsp->result = 0;
+
+	if (c->recfmt != 0) {
+		pr_warn("invalid connect version (%d).\n",
+			le16_to_cpu(c->recfmt));
+		status = NVME_SC_CONNECT_FORMAT | NVME_SC_DNR;
+		goto out;
+	}
+
+	if (unlikely(d->cntlid != cpu_to_le16(0xffff))) {
+		pr_warn("connect attempt for invalid controller ID %#x\n",
+			d->cntlid);
+		status = NVME_SC_CONNECT_INVALID_PARAM | NVME_SC_DNR;
+		req->rsp->result = IPO_IATTR_CONNECT_DATA(cntlid);
+		goto out;
+	}
+
+	status = nvmet_alloc_ctrl(d->subsysnqn, d->hostnqn, req,
+			le32_to_cpu(c->kato), &ctrl);
+	if (status)
+		goto out;
+
+	status = nvmet_install_queue(ctrl, req);
+	if (status) {
+		nvmet_ctrl_put(ctrl);
+		goto out;
+	}
+
+	pr_info("creating controller %d for NQN %s.\n",
+			ctrl->cntlid, ctrl->hostnqn);
+	req->rsp->result16 = cpu_to_le16(ctrl->cntlid);
+
+out:
+	kunmap(sg_page(req->sg));
+	nvmet_req_complete(req, status);
+}
+
+static void nvmet_execute_io_connect(struct nvmet_req *req)
+{
+	struct nvmf_connect_command *c = &req->cmd->connect;
+	struct nvmf_connect_data *d;
+	struct nvmet_ctrl *ctrl = NULL;
+	u16 qid = le16_to_cpu(c->qid);
+	u16 status = 0;
+
+	d = kmap(sg_page(req->sg)) + req->sg->offset;
+
+	/* zero out initial completion result, assign values as needed */
+	req->rsp->result = 0;
+
+	if (c->recfmt != 0) {
+		pr_warn("invalid connect version (%d).\n",
+			le16_to_cpu(c->recfmt));
+		status = NVME_SC_CONNECT_FORMAT | NVME_SC_DNR;
+		goto out;
+	}
+
+	status = nvmet_ctrl_find_get(d->subsysnqn, d->hostnqn,
+			le16_to_cpu(d->cntlid),
+			req, &ctrl);
+	if (status)
+		goto out;
+
+	if (unlikely(qid > ctrl->subsys->max_qid)) {
+		pr_warn("invalid queue id (%d)\n", qid);
+		status = NVME_SC_CONNECT_INVALID_PARAM | NVME_SC_DNR;
+		req->rsp->result = IPO_IATTR_CONNECT_SQE(qid);
+		goto out_ctrl_put;
+	}
+
+	status = nvmet_install_queue(ctrl, req);
+	if (status) {
+		/* pass back cntlid that had the issue of installing queue */
+		req->rsp->result16 = cpu_to_le16(ctrl->cntlid);
+		goto out_ctrl_put;
+	}
+
+	pr_info("adding queue %d to ctrl %d.\n", qid, ctrl->cntlid);
+
+out:
+	kunmap(sg_page(req->sg));
+	nvmet_req_complete(req, status);
+	return;
+
+out_ctrl_put:
+	nvmet_ctrl_put(ctrl);
+	goto out;
+}
+
+int nvmet_parse_connect_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	req->ns = NULL;
+
+	if (req->cmd->common.opcode != nvme_fabrics_command) {
+		pr_err("invalid command 0x%x on unconnected queue.\n",
+			cmd->fabrics.opcode);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+	if (cmd->fabrics.fctype != nvme_fabrics_type_connect) {
+		pr_err("invalid capsule type 0x%x on unconnected queue.\n",
+			cmd->fabrics.fctype);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+
+	req->data_len = sizeof(struct nvmf_connect_data);
+	if (cmd->connect.qid == 0)
+		req->execute = nvmet_execute_admin_connect;
+	else
+		req->execute = nvmet_execute_io_connect;
+	return 0;
+}
diff --git a/drivers/nvme/target/io-cmd.c b/drivers/nvme/target/io-cmd.c
new file mode 100644
index 0000000..76dbf73
--- /dev/null
+++ b/drivers/nvme/target/io-cmd.c
@@ -0,0 +1,213 @@
+/*
+ * NVMe I/O command implementation.
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/blkdev.h>
+#include <linux/module.h>
+#include "nvmet.h"
+
+static void nvmet_bio_done(struct bio *bio)
+{
+	struct nvmet_req *req = bio->bi_private;
+
+	nvmet_req_complete(req,
+		bio->bi_error ? NVME_SC_INTERNAL | NVME_SC_DNR : 0);
+
+	if (bio != &req->inline_bio)
+		bio_put(bio);
+}
+
+static inline u32 nvmet_rw_len(struct nvmet_req *req)
+{
+	return ((u32)le16_to_cpu(req->cmd->rw.length) + 1) <<
+			req->ns->blksize_shift;
+}
+
+static void nvmet_inline_bio_init(struct nvmet_req *req)
+{
+	struct bio *bio = &req->inline_bio;
+
+	bio_init(bio);
+	bio->bi_max_vecs = NVMET_MAX_INLINE_BIOVEC;
+	bio->bi_io_vec = req->inline_bvec;
+}
+
+static void nvmet_execute_rw(struct nvmet_req *req)
+{
+	int sg_cnt = req->sg_cnt;
+	struct scatterlist *sg;
+	struct bio *bio;
+	sector_t sector;
+	blk_qc_t cookie;
+	int rw, i;
+
+	if (!req->sg_cnt) {
+		nvmet_req_complete(req, 0);
+		return;
+	}
+
+	if (req->cmd->rw.opcode == nvme_cmd_write) {
+		if (req->cmd->rw.control & cpu_to_le16(NVME_RW_FUA))
+			rw = WRITE_FUA;
+		else
+			rw = WRITE;
+	} else {
+		rw = READ;
+	}
+
+	sector = le64_to_cpu(req->cmd->rw.slba);
+	sector <<= (req->ns->blksize_shift - 9);
+
+	nvmet_inline_bio_init(req);
+	bio = &req->inline_bio;
+	bio->bi_bdev = req->ns->bdev;
+	bio->bi_iter.bi_sector = sector;
+	bio->bi_private = req;
+	bio->bi_end_io = nvmet_bio_done;
+
+	for_each_sg(req->sg, sg, req->sg_cnt, i) {
+		while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
+				!= sg->length) {
+			struct bio *prev = bio;
+
+			bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
+			bio->bi_bdev = req->ns->bdev;
+			bio->bi_iter.bi_sector = sector;
+
+			bio_chain(bio, prev);
+			cookie = submit_bio(rw, prev);
+		}
+
+		sector += sg->length >> 9;
+		sg_cnt--;
+	}
+
+	cookie = submit_bio(rw, bio);
+
+	blk_poll(bdev_get_queue(req->ns->bdev), cookie);
+}
+
+static void nvmet_execute_flush(struct nvmet_req *req)
+{
+	struct bio *bio;
+
+	nvmet_inline_bio_init(req);
+	bio = &req->inline_bio;
+
+	bio->bi_bdev = req->ns->bdev;
+	bio->bi_private = req;
+	bio->bi_end_io = nvmet_bio_done;
+
+	submit_bio(WRITE_FLUSH, bio);
+}
+
+static u16 nvmet_discard_range(struct nvmet_ns *ns,
+		struct nvme_dsm_range *range, int type, struct bio **bio)
+{
+	if (__blkdev_issue_discard(ns->bdev,
+			le64_to_cpu(range->slba) << (ns->blksize_shift - 9),
+			le32_to_cpu(range->nlb) << (ns->blksize_shift - 9),
+			GFP_KERNEL, type, bio))
+		return NVME_SC_INTERNAL | NVME_SC_DNR;
+	return 0;
+}
+
+static void nvmet_execute_discard(struct nvmet_req *req)
+{
+	struct nvme_dsm_range range;
+	struct bio *bio = NULL;
+	int type = REQ_WRITE | REQ_DISCARD, i;
+	u16 status;
+
+	for (i = 0; i <= le32_to_cpu(req->cmd->dsm.nr); i++) {
+		status = nvmet_copy_from_sgl(req, i * sizeof(range), &range,
+				sizeof(range));
+		if (status)
+			break;
+
+		status = nvmet_discard_range(req->ns, &range, type, &bio);
+		if (status)
+			break;
+	}
+
+	if (bio) {
+		bio->bi_private = req;
+		bio->bi_end_io = nvmet_bio_done;
+		if (status) {
+			bio->bi_error = -EIO;
+			bio_endio(bio);
+		} else {
+			submit_bio(type, bio);
+		}
+	} else {
+		nvmet_req_complete(req, status);
+	}
+}
+
+static void nvmet_execute_dsm(struct nvmet_req *req)
+{
+	switch (le32_to_cpu(req->cmd->dsm.attributes)) {
+	case NVME_DSMGMT_AD:
+		nvmet_execute_discard(req);
+		return;
+	case NVME_DSMGMT_IDR:
+	case NVME_DSMGMT_IDW:
+	default:
+		/* Not supported yet */
+		nvmet_req_complete(req, 0);
+		return;
+	}
+}
+
+int nvmet_parse_io_cmd(struct nvmet_req *req)
+{
+	struct nvme_command *cmd = req->cmd;
+
+	if (unlikely(!(req->sq->ctrl->cc & NVME_CC_ENABLE))) {
+		pr_err("nvmet: got io cmd %d while CC.EN == 0\n",
+				cmd->common.opcode);
+		req->ns = NULL;
+		return NVME_SC_CMD_SEQ_ERROR | NVME_SC_DNR;
+	}
+
+	if (unlikely(!(req->sq->ctrl->csts & NVME_CSTS_RDY))) {
+		pr_err("nvmet: got io cmd %d while CSTS.RDY == 0\n",
+				cmd->common.opcode);
+		req->ns = NULL;
+		return NVME_SC_CMD_SEQ_ERROR | NVME_SC_DNR;
+	}
+
+	req->ns = nvmet_find_namespace(req->sq->ctrl, cmd->rw.nsid);
+	if (!req->ns)
+		return NVME_SC_INVALID_NS | NVME_SC_DNR;
+
+	switch (cmd->common.opcode) {
+	case nvme_cmd_read:
+	case nvme_cmd_write:
+		req->execute = nvmet_execute_rw;
+		req->data_len = nvmet_rw_len(req);
+		return 0;
+	case nvme_cmd_flush:
+		req->execute = nvmet_execute_flush;
+		req->data_len = 0;
+		return 0;
+	case nvme_cmd_dsm:
+		req->execute = nvmet_execute_dsm;
+		req->data_len = le32_to_cpu(cmd->dsm.nr) *
+			sizeof(struct nvme_dsm_range);
+		return 0;
+	default:
+		pr_err("nvmet: unhandled cmd %d\n", cmd->common.opcode);
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+}
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
new file mode 100644
index 0000000..57dd6d8
--- /dev/null
+++ b/drivers/nvme/target/nvmet.h
@@ -0,0 +1,331 @@
+/*
+ * Copyright (c) 2015-2016 HGST, a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+
+#ifndef _NVMET_H
+#define _NVMET_H
+
+#include <linux/dma-mapping.h>
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/kref.h>
+#include <linux/percpu-refcount.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/nvme.h>
+#include <linux/configfs.h>
+#include <linux/rcupdate.h>
+#include <linux/blkdev.h>
+
+#define NVMET_ASYNC_EVENTS		4
+#define NVMET_ERROR_LOG_SLOTS		128
+
+/* Helper Macros when NVMe error is NVME_SC_CONNECT_INVALID_PARAM
+ * The 16 bit shift is to set IATTR bit to 1, which means offending
+ * offset starts in the data section of connect()
+ */
+#define IPO_IATTR_CONNECT_DATA(x)	\
+	(cpu_to_le32((1 << 16) | (offsetof(struct nvmf_connect_data, x))))
+#define IPO_IATTR_CONNECT_SQE(x)	\
+	(cpu_to_le32(offsetof(struct nvmf_connect_command, x)))
+
+struct nvmet_ns {
+	struct list_head	dev_link;
+	struct percpu_ref	ref;
+	struct block_device	*bdev;
+	u32			nsid;
+	u32			blksize_shift;
+	loff_t			size;
+	u8			nguid[16];
+
+	struct nvmet_subsys	*subsys;
+	const char		*device_path;
+
+	struct config_group	device_group;
+	struct config_group	group;
+
+	struct completion	disable_done;
+};
+
+static inline struct nvmet_ns *to_nvmet_ns(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct nvmet_ns, group);
+}
+
+static inline bool nvmet_ns_enabled(struct nvmet_ns *ns)
+{
+	return !list_empty_careful(&ns->dev_link);
+}
+
+struct nvmet_cq {
+	u16			qid;
+	u16			size;
+};
+
+struct nvmet_sq {
+	struct nvmet_ctrl	*ctrl;
+	struct percpu_ref	ref;
+	u16			qid;
+	u16			size;
+	struct completion	free_done;
+};
+
+/**
+ * struct nvmet_port -	Common structure to keep port
+ *				information for the target.
+ * @entry:		List head for holding a list of these elements.
+ * @disc_addr:		Address information is stored in a format defined
+ *				for a discovery log page entry.
+ * @group:		ConfigFS group for this element's folder.
+ * @priv:		Private data for the transport.
+ */
+struct nvmet_port {
+	struct list_head		entry;
+	struct nvmf_disc_rsp_page_entry	disc_addr;
+	struct config_group		group;
+	struct config_group		subsys_group;
+	struct list_head		subsystems;
+	struct config_group		referrals_group;
+	struct list_head		referrals;
+	void				*priv;
+	bool				enabled;
+};
+
+static inline struct nvmet_port *to_nvmet_port(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct nvmet_port,
+			group);
+}
+
+struct nvmet_ctrl {
+	struct nvmet_subsys	*subsys;
+	struct nvmet_cq		**cqs;
+	struct nvmet_sq		**sqs;
+
+	struct mutex		lock;
+	u64			cap;
+	u32			cc;
+	u32			csts;
+
+	u16			cntlid;
+	u32			kato;
+
+	struct nvmet_req	*async_event_cmds[NVMET_ASYNC_EVENTS];
+	unsigned int		nr_async_event_cmds;
+	struct list_head	async_events;
+	struct work_struct	async_event_work;
+
+	struct list_head	subsys_entry;
+	struct kref		ref;
+	struct delayed_work	ka_work;
+	struct work_struct	fatal_err_work;
+
+	struct nvmet_fabrics_ops *ops;
+
+	char			subsysnqn[NVMF_NQN_FIELD_LEN];
+	char			hostnqn[NVMF_NQN_FIELD_LEN];
+};
+
+struct nvmet_subsys {
+	enum nvme_subsys_type	type;
+
+	struct mutex		lock;
+	struct kref		ref;
+
+	struct list_head	namespaces;
+	unsigned int		max_nsid;
+
+	struct list_head	ctrls;
+	struct ida		cntlid_ida;
+
+	struct list_head	hosts;
+	bool			allow_any_host;
+
+	u16			max_qid;
+
+	u64			ver;
+	char			*subsysnqn;
+
+	struct config_group	group;
+
+	struct config_group	namespaces_group;
+	struct config_group	allowed_hosts_group;
+};
+
+static inline struct nvmet_subsys *to_subsys(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct nvmet_subsys, group);
+}
+
+static inline struct nvmet_subsys *namespaces_to_subsys(
+		struct config_item *item)
+{
+	return container_of(to_config_group(item), struct nvmet_subsys,
+			namespaces_group);
+}
+
+struct nvmet_host {
+	struct config_group	group;
+};
+
+static inline struct nvmet_host *to_host(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct nvmet_host, group);
+}
+
+static inline char *nvmet_host_name(struct nvmet_host *host)
+{
+	return config_item_name(&host->group.cg_item);
+}
+
+struct nvmet_host_link {
+	struct list_head	entry;
+	struct nvmet_host	*host;
+};
+
+struct nvmet_subsys_link {
+	struct list_head	entry;
+	struct nvmet_subsys	*subsys;
+};
+
+struct nvmet_req;
+struct nvmet_fabrics_ops {
+	struct module *owner;
+	unsigned int type;
+	unsigned int sqe_inline_size;
+	unsigned int msdbd;
+	bool has_keyed_sgls : 1;
+	void (*queue_response)(struct nvmet_req *req);
+	int (*add_port)(struct nvmet_port *port);
+	void (*remove_port)(struct nvmet_port *port);
+	void (*delete_ctrl)(struct nvmet_ctrl *ctrl);
+};
+
+#define NVMET_MAX_INLINE_BIOVEC	8
+
+struct nvmet_req {
+	struct nvme_command	*cmd;
+	struct nvme_completion	*rsp;
+	struct nvmet_sq		*sq;
+	struct nvmet_cq		*cq;
+	struct nvmet_ns		*ns;
+	struct scatterlist	*sg;
+	struct bio		inline_bio;
+	struct bio_vec		inline_bvec[NVMET_MAX_INLINE_BIOVEC];
+	int			sg_cnt;
+	size_t			data_len;
+
+	struct nvmet_port	*port;
+
+	void (*execute)(struct nvmet_req *req);
+	struct nvmet_fabrics_ops *ops;
+};
+
+static inline void nvmet_set_status(struct nvmet_req *req, u16 status)
+{
+	req->rsp->status = cpu_to_le16(status << 1);
+}
+
+static inline void nvmet_set_result(struct nvmet_req *req, u32 result)
+{
+	req->rsp->result = cpu_to_le32(result);
+}
+
+/*
+ * NVMe command writes actually are DMA reads for us on the target side.
+ */
+static inline enum dma_data_direction
+nvmet_data_dir(struct nvmet_req *req)
+{
+	return nvme_is_write(req->cmd) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+}
+
+struct nvmet_async_event {
+	struct list_head	entry;
+	u8			event_type;
+	u8			event_info;
+	u8			log_page;
+};
+
+int nvmet_parse_connect_cmd(struct nvmet_req *req);
+int nvmet_parse_io_cmd(struct nvmet_req *req);
+int nvmet_parse_admin_cmd(struct nvmet_req *req);
+int nvmet_parse_discovery_cmd(struct nvmet_req *req);
+int nvmet_parse_fabrics_cmd(struct nvmet_req *req);
+
+bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
+		struct nvmet_sq *sq, struct nvmet_fabrics_ops *ops);
+void nvmet_req_complete(struct nvmet_req *req, u16 status);
+
+void nvmet_cq_setup(struct nvmet_ctrl *ctrl, struct nvmet_cq *cq, u16 qid,
+		u16 size);
+void nvmet_sq_setup(struct nvmet_ctrl *ctrl, struct nvmet_sq *sq, u16 qid,
+		u16 size);
+void nvmet_sq_destroy(struct nvmet_sq *sq);
+int nvmet_sq_init(struct nvmet_sq *sq);
+
+void nvmet_ctrl_fatal_error(struct nvmet_ctrl *ctrl);
+
+void nvmet_update_cc(struct nvmet_ctrl *ctrl, u32 new);
+u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
+		struct nvmet_req *req, u32 kato, struct nvmet_ctrl **ctrlp);
+u16 nvmet_ctrl_find_get(const char *subsysnqn, const char *hostnqn, u16 cntlid,
+		struct nvmet_req *req, struct nvmet_ctrl **ret);
+void nvmet_ctrl_put(struct nvmet_ctrl *ctrl);
+
+struct nvmet_subsys *nvmet_subsys_alloc(const char *subsysnqn,
+		enum nvme_subsys_type type);
+void nvmet_subsys_put(struct nvmet_subsys *subsys);
+
+struct nvmet_ns *nvmet_find_namespace(struct nvmet_ctrl *ctrl, __le32 nsid);
+void nvmet_put_namespace(struct nvmet_ns *ns);
+int nvmet_ns_enable(struct nvmet_ns *ns);
+void nvmet_ns_disable(struct nvmet_ns *ns);
+struct nvmet_ns *nvmet_ns_alloc(struct nvmet_subsys *subsys, u32 nsid);
+void nvmet_ns_free(struct nvmet_ns *ns);
+
+int nvmet_register_transport(struct nvmet_fabrics_ops *ops);
+void nvmet_unregister_transport(struct nvmet_fabrics_ops *ops);
+
+int nvmet_enable_port(struct nvmet_port *port);
+void nvmet_disable_port(struct nvmet_port *port);
+
+void nvmet_referral_enable(struct nvmet_port *parent, struct nvmet_port *port);
+void nvmet_referral_disable(struct nvmet_port *port);
+
+u16 nvmet_copy_to_sgl(struct nvmet_req *req, off_t off, const void *buf,
+		size_t len);
+u16 nvmet_copy_from_sgl(struct nvmet_req *req, off_t off, void *buf,
+		size_t len);
+
+u32 nvmet_get_log_page_len(struct nvme_command *cmd);
+
+#define NVMET_QUEUE_SIZE	1024
+#define NVMET_NR_QUEUES		64
+#define NVMET_MAX_CMD		NVMET_QUEUE_SIZE
+#define NVMET_KAS		10
+#define NVMET_DISC_KATO		120
+
+int __init nvmet_init_configfs(void);
+void __exit nvmet_exit_configfs(void);
+
+int __init nvmet_init_discovery(void);
+void nvmet_exit_discovery(void);
+
+extern struct nvmet_subsys *nvmet_disc_subsys;
+extern u64 nvmet_genctr;
+extern struct rw_semaphore nvmet_config_sem;
+
+bool nvmet_host_allowed(struct nvmet_req *req, struct nvmet_subsys *subsys,
+		const char *hostnqn);
+
+#endif /* _NVMET_H */
