1 files changed, 900 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
new file mode 100644
index 000000000..98a34ed10
--- /dev/null
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -0,0 +1,900 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SCSI RDMA (SRP) transport class
+ *
+ * Copyright (C) 2007 FUJITA Tomonori <tomof@acm.org>
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/jiffies.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_transport.h>
+#include <scsi/scsi_transport_srp.h>
+#include "scsi_priv.h"
+
+struct srp_host_attrs {
+	atomic_t next_port_id;
+};
+#define to_srp_host_attrs(host)	((struct srp_host_attrs *)(host)->shost_data)
+
+#define SRP_HOST_ATTRS 0
+#define SRP_RPORT_ATTRS 8
+
+struct srp_internal {
+	struct scsi_transport_template t;
+	struct srp_function_template *f;
+
+	struct device_attribute *host_attrs[SRP_HOST_ATTRS + 1];
+
+	struct device_attribute *rport_attrs[SRP_RPORT_ATTRS + 1];
+	struct transport_container rport_attr_cont;
+};
+
+static int scsi_is_srp_rport(const struct device *dev);
+
+#define to_srp_internal(tmpl) container_of(tmpl, struct srp_internal, t)
+
+#define	dev_to_rport(d)	container_of(d, struct srp_rport, dev)
+#define transport_class_to_srp_rport(dev) dev_to_rport((dev)->parent)
+static inline struct Scsi_Host *rport_to_shost(struct srp_rport *r)
+{
+	return dev_to_shost(r->dev.parent);
+}
+
+static int find_child_rport(struct device *dev, void *data)
+{
+	struct device **child = data;
+
+	if (scsi_is_srp_rport(dev)) {
+		WARN_ON_ONCE(*child);
+		*child = dev;
+	}
+	return 0;
+}
+
+static inline struct srp_rport *shost_to_rport(struct Scsi_Host *shost)
+{
+	struct device *child = NULL;
+
+	WARN_ON_ONCE(device_for_each_child(&shost->shost_gendev, &child,
+					   find_child_rport) < 0);
+	return child ? dev_to_rport(child) : NULL;
+}
+
+/**
+ * srp_tmo_valid() - check timeout combination validity
+ * @reconnect_delay: Reconnect delay in seconds.
+ * @fast_io_fail_tmo: Fast I/O fail timeout in seconds.
+ * @dev_loss_tmo: Device loss timeout in seconds.
+ *
+ * The combination of the timeout parameters must be such that SCSI commands
+ * are finished in a reasonable time. Hence do not allow the fast I/O fail
+ * timeout to exceed SCSI_DEVICE_BLOCK_MAX_TIMEOUT nor allow dev_loss_tmo to
+ * exceed that limit if failing I/O fast has been disabled. Furthermore, these
+ * parameters must be such that multipath can detect failed paths timely.
+ * Hence do not allow all three parameters to be disabled simultaneously.
+ */
+int srp_tmo_valid(int reconnect_delay, int fast_io_fail_tmo, long dev_loss_tmo)
+{
+	if (reconnect_delay < 0 && fast_io_fail_tmo < 0 && dev_loss_tmo < 0)
+		return -EINVAL;
+	if (reconnect_delay == 0)
+		return -EINVAL;
+	if (fast_io_fail_tmo > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
+		return -EINVAL;
+	if (fast_io_fail_tmo < 0 &&
+	    dev_loss_tmo > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
+		return -EINVAL;
+	if (dev_loss_tmo >= LONG_MAX / HZ)
+		return -EINVAL;
+	if (fast_io_fail_tmo >= 0 && dev_loss_tmo >= 0 &&
+	    fast_io_fail_tmo >= dev_loss_tmo)
+		return -EINVAL;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(srp_tmo_valid);
+
+static int srp_host_setup(struct transport_container *tc, struct device *dev,
+			  struct device *cdev)
+{
+	struct Scsi_Host *shost = dev_to_shost(dev);
+	struct srp_host_attrs *srp_host = to_srp_host_attrs(shost);
+
+	atomic_set(&srp_host->next_port_id, 0);
+	return 0;
+}
+
+static DECLARE_TRANSPORT_CLASS(srp_host_class, "srp_host", srp_host_setup,
+			       NULL, NULL);
+
+static DECLARE_TRANSPORT_CLASS(srp_rport_class, "srp_remote_ports",
+			       NULL, NULL, NULL);
+
+static ssize_t
+show_srp_rport_id(struct device *dev, struct device_attribute *attr,
+		  char *buf)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+	return sprintf(buf, "%16phC\n", rport->port_id);
+}
+
+static DEVICE_ATTR(port_id, S_IRUGO, show_srp_rport_id, NULL);
+
+static const struct {
+	u32 value;
+	char *name;
+} srp_rport_role_names[] = {
+	{SRP_RPORT_ROLE_INITIATOR, "SRP Initiator"},
+	{SRP_RPORT_ROLE_TARGET, "SRP Target"},
+};
+
+static ssize_t
+show_srp_rport_roles(struct device *dev, struct device_attribute *attr,
+		     char *buf)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+	int i;
+	char *name = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(srp_rport_role_names); i++)
+		if (srp_rport_role_names[i].value == rport->roles) {
+			name = srp_rport_role_names[i].name;
+			break;
+		}
+	return sprintf(buf, "%s\n", name ? : "unknown");
+}
+
+static DEVICE_ATTR(roles, S_IRUGO, show_srp_rport_roles, NULL);
+
+static ssize_t store_srp_rport_delete(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+	struct Scsi_Host *shost = dev_to_shost(dev);
+	struct srp_internal *i = to_srp_internal(shost->transportt);
+
+	if (i->f->rport_delete) {
+		i->f->rport_delete(rport);
+		return count;
+	} else {
+		return -ENOSYS;
+	}
+}
+
+static DEVICE_ATTR(delete, S_IWUSR, NULL, store_srp_rport_delete);
+
+static ssize_t show_srp_rport_state(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	static const char *const state_name[] = {
+		[SRP_RPORT_RUNNING]	= "running",
+		[SRP_RPORT_BLOCKED]	= "blocked",
+		[SRP_RPORT_FAIL_FAST]	= "fail-fast",
+		[SRP_RPORT_LOST]	= "lost",
+	};
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+	enum srp_rport_state state = rport->state;
+
+	return sprintf(buf, "%s\n",
+		       (unsigned)state < ARRAY_SIZE(state_name) ?
+		       state_name[state] : "???");
+}
+
+static DEVICE_ATTR(state, S_IRUGO, show_srp_rport_state, NULL);
+
+static ssize_t srp_show_tmo(char *buf, int tmo)
+{
+	return tmo >= 0 ? sprintf(buf, "%d\n", tmo) : sprintf(buf, "off\n");
+}
+
+int srp_parse_tmo(int *tmo, const char *buf)
+{
+	int res = 0;
+
+	if (strncmp(buf, "off", 3) != 0)
+		res = kstrtoint(buf, 0, tmo);
+	else
+		*tmo = -1;
+
+	return res;
+}
+EXPORT_SYMBOL(srp_parse_tmo);
+
+static ssize_t show_reconnect_delay(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+
+	return srp_show_tmo(buf, rport->reconnect_delay);
+}
+
+static ssize_t store_reconnect_delay(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, const size_t count)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+	int res, delay;
+
+	res = srp_parse_tmo(&delay, buf);
+	if (res)
+		goto out;
+	res = srp_tmo_valid(delay, rport->fast_io_fail_tmo,
+			    rport->dev_loss_tmo);
+	if (res)
+		goto out;
+
+	if (rport->reconnect_delay <= 0 && delay > 0 &&
+	    rport->state != SRP_RPORT_RUNNING) {
+		queue_delayed_work(system_long_wq, &rport->reconnect_work,
+				   delay * HZ);
+	} else if (delay <= 0) {
+		cancel_delayed_work(&rport->reconnect_work);
+	}
+	rport->reconnect_delay = delay;
+	res = count;
+
+out:
+	return res;
+}
+
+static DEVICE_ATTR(reconnect_delay, S_IRUGO | S_IWUSR, show_reconnect_delay,
+		   store_reconnect_delay);
+
+static ssize_t show_failed_reconnects(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+
+	return sprintf(buf, "%d\n", rport->failed_reconnects);
+}
+
+static DEVICE_ATTR(failed_reconnects, S_IRUGO, show_failed_reconnects, NULL);
+
+static ssize_t show_srp_rport_fast_io_fail_tmo(struct device *dev,
+					       struct device_attribute *attr,
+					       char *buf)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+
+	return srp_show_tmo(buf, rport->fast_io_fail_tmo);
+}
+
+static ssize_t store_srp_rport_fast_io_fail_tmo(struct device *dev,
+						struct device_attribute *attr,
+						const char *buf, size_t count)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+	int res;
+	int fast_io_fail_tmo;
+
+	res = srp_parse_tmo(&fast_io_fail_tmo, buf);
+	if (res)
+		goto out;
+	res = srp_tmo_valid(rport->reconnect_delay, fast_io_fail_tmo,
+			    rport->dev_loss_tmo);
+	if (res)
+		goto out;
+	rport->fast_io_fail_tmo = fast_io_fail_tmo;
+	res = count;
+
+out:
+	return res;
+}
+
+static DEVICE_ATTR(fast_io_fail_tmo, S_IRUGO | S_IWUSR,
+		   show_srp_rport_fast_io_fail_tmo,
+		   store_srp_rport_fast_io_fail_tmo);
+
+static ssize_t show_srp_rport_dev_loss_tmo(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+
+	return srp_show_tmo(buf, rport->dev_loss_tmo);
+}
+
+static ssize_t store_srp_rport_dev_loss_tmo(struct device *dev,
+					    struct device_attribute *attr,
+					    const char *buf, size_t count)
+{
+	struct srp_rport *rport = transport_class_to_srp_rport(dev);
+	int res;
+	int dev_loss_tmo;
+
+	res = srp_parse_tmo(&dev_loss_tmo, buf);
+	if (res)
+		goto out;
+	res = srp_tmo_valid(rport->reconnect_delay, rport->fast_io_fail_tmo,
+			    dev_loss_tmo);
+	if (res)
+		goto out;
+	rport->dev_loss_tmo = dev_loss_tmo;
+	res = count;
+
+out:
+	return res;
+}
+
+static DEVICE_ATTR(dev_loss_tmo, S_IRUGO | S_IWUSR,
+		   show_srp_rport_dev_loss_tmo,
+		   store_srp_rport_dev_loss_tmo);
+
+static int srp_rport_set_state(struct srp_rport *rport,
+			       enum srp_rport_state new_state)
+{
+	enum srp_rport_state old_state = rport->state;
+
+	lockdep_assert_held(&rport->mutex);
+
+	switch (new_state) {
+	case SRP_RPORT_RUNNING:
+		switch (old_state) {
+		case SRP_RPORT_LOST:
+			goto invalid;
+		default:
+			break;
+		}
+		break;
+	case SRP_RPORT_BLOCKED:
+		switch (old_state) {
+		case SRP_RPORT_RUNNING:
+			break;
+		default:
+			goto invalid;
+		}
+		break;
+	case SRP_RPORT_FAIL_FAST:
+		switch (old_state) {
+		case SRP_RPORT_LOST:
+			goto invalid;
+		default:
+			break;
+		}
+		break;
+	case SRP_RPORT_LOST:
+		break;
+	}
+	rport->state = new_state;
+	return 0;
+
+invalid:
+	return -EINVAL;
+}
+
+/**
+ * srp_reconnect_work() - reconnect and schedule a new attempt if necessary
+ * @work: Work structure used for scheduling this operation.
+ */
+static void srp_reconnect_work(struct work_struct *work)
+{
+	struct srp_rport *rport = container_of(to_delayed_work(work),
+					struct srp_rport, reconnect_work);
+	struct Scsi_Host *shost = rport_to_shost(rport);
+	int delay, res;
+
+	res = srp_reconnect_rport(rport);
+	if (res != 0) {
+		shost_printk(KERN_ERR, shost,
+			     "reconnect attempt %d failed (%d)\n",
+			     ++rport->failed_reconnects, res);
+		delay = rport->reconnect_delay *
+			min(100, max(1, rport->failed_reconnects - 10));
+		if (delay > 0)
+			queue_delayed_work(system_long_wq,
+					   &rport->reconnect_work, delay * HZ);
+	}
+}
+
+/*
+ * scsi_target_block() must have been called before this function is
+ * called to guarantee that no .queuecommand() calls are in progress.
+ */
+static void __rport_fail_io_fast(struct srp_rport *rport)
+{
+	struct Scsi_Host *shost = rport_to_shost(rport);
+	struct srp_internal *i;
+
+	lockdep_assert_held(&rport->mutex);
+
+	if (srp_rport_set_state(rport, SRP_RPORT_FAIL_FAST))
+		return;
+
+	scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE);
+
+	/* Involve the LLD if possible to terminate all I/O on the rport. */
+	i = to_srp_internal(shost->transportt);
+	if (i->f->terminate_rport_io)
+		i->f->terminate_rport_io(rport);
+}
+
+/**
+ * rport_fast_io_fail_timedout() - fast I/O failure timeout handler
+ * @work: Work structure used for scheduling this operation.
+ */
+static void rport_fast_io_fail_timedout(struct work_struct *work)
+{
+	struct srp_rport *rport = container_of(to_delayed_work(work),
+					struct srp_rport, fast_io_fail_work);
+	struct Scsi_Host *shost = rport_to_shost(rport);
+
+	pr_info("fast_io_fail_tmo expired for SRP %s / %s.\n",
+		dev_name(&rport->dev), dev_name(&shost->shost_gendev));
+
+	mutex_lock(&rport->mutex);
+	if (rport->state == SRP_RPORT_BLOCKED)
+		__rport_fail_io_fast(rport);
+	mutex_unlock(&rport->mutex);
+}
+
+/**
+ * rport_dev_loss_timedout() - device loss timeout handler
+ * @work: Work structure used for scheduling this operation.
+ */
+static void rport_dev_loss_timedout(struct work_struct *work)
+{
+	struct srp_rport *rport = container_of(to_delayed_work(work),
+					struct srp_rport, dev_loss_work);
+	struct Scsi_Host *shost = rport_to_shost(rport);
+	struct srp_internal *i = to_srp_internal(shost->transportt);
+
+	pr_info("dev_loss_tmo expired for SRP %s / %s.\n",
+		dev_name(&rport->dev), dev_name(&shost->shost_gendev));
+
+	mutex_lock(&rport->mutex);
+	WARN_ON(srp_rport_set_state(rport, SRP_RPORT_LOST) != 0);
+	scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE);
+	mutex_unlock(&rport->mutex);
+
+	i->f->rport_delete(rport);
+}
+
+static void __srp_start_tl_fail_timers(struct srp_rport *rport)
+{
+	struct Scsi_Host *shost = rport_to_shost(rport);
+	int delay, fast_io_fail_tmo, dev_loss_tmo;
+
+	lockdep_assert_held(&rport->mutex);
+
+	delay = rport->reconnect_delay;
+	fast_io_fail_tmo = rport->fast_io_fail_tmo;
+	dev_loss_tmo = rport->dev_loss_tmo;
+	pr_debug("%s current state: %d\n", dev_name(&shost->shost_gendev),
+		 rport->state);
+
+	if (rport->state == SRP_RPORT_LOST)
+		return;
+	if (delay > 0)
+		queue_delayed_work(system_long_wq, &rport->reconnect_work,
+				   1UL * delay * HZ);
+	if ((fast_io_fail_tmo >= 0 || dev_loss_tmo >= 0) &&
+	    srp_rport_set_state(rport, SRP_RPORT_BLOCKED) == 0) {
+		pr_debug("%s new state: %d\n", dev_name(&shost->shost_gendev),
+			 rport->state);
+		scsi_target_block(&shost->shost_gendev);
+		if (fast_io_fail_tmo >= 0)
+			queue_delayed_work(system_long_wq,
+					   &rport->fast_io_fail_work,
+					   1UL * fast_io_fail_tmo * HZ);
+		if (dev_loss_tmo >= 0)
+			queue_delayed_work(system_long_wq,
+					   &rport->dev_loss_work,
+					   1UL * dev_loss_tmo * HZ);
+	}
+}
+
+/**
+ * srp_start_tl_fail_timers() - start the transport layer failure timers
+ * @rport: SRP target port.
+ *
+ * Start the transport layer fast I/O failure and device loss timers. Do not
+ * modify a timer that was already started.
+ */
+void srp_start_tl_fail_timers(struct srp_rport *rport)
+{
+	mutex_lock(&rport->mutex);
+	__srp_start_tl_fail_timers(rport);
+	mutex_unlock(&rport->mutex);
+}
+EXPORT_SYMBOL(srp_start_tl_fail_timers);
+
+/**
+ * srp_reconnect_rport() - reconnect to an SRP target port
+ * @rport: SRP target port.
+ *
+ * Blocks SCSI command queueing before invoking reconnect() such that
+ * queuecommand() won't be invoked concurrently with reconnect() from outside
+ * the SCSI EH. This is important since a reconnect() implementation may
+ * reallocate resources needed by queuecommand().
+ *
+ * Notes:
+ * - This function neither waits until outstanding requests have finished nor
+ *   tries to abort these. It is the responsibility of the reconnect()
+ *   function to finish outstanding commands before reconnecting to the target
+ *   port.
+ * - It is the responsibility of the caller to ensure that the resources
+ *   reallocated by the reconnect() function won't be used while this function
+ *   is in progress. One possible strategy is to invoke this function from
+ *   the context of the SCSI EH thread only. Another possible strategy is to
+ *   lock the rport mutex inside each SCSI LLD callback that can be invoked by
+ *   the SCSI EH (the scsi_host_template.eh_*() functions and also the
+ *   scsi_host_template.queuecommand() function).
+ */
+int srp_reconnect_rport(struct srp_rport *rport)
+{
+	struct Scsi_Host *shost = rport_to_shost(rport);
+	struct srp_internal *i = to_srp_internal(shost->transportt);
+	struct scsi_device *sdev;
+	int res;
+
+	pr_debug("SCSI host %s\n", dev_name(&shost->shost_gendev));
+
+	res = mutex_lock_interruptible(&rport->mutex);
+	if (res)
+		goto out;
+	if (rport->state != SRP_RPORT_FAIL_FAST && rport->state != SRP_RPORT_LOST)
+		/*
+		 * sdev state must be SDEV_TRANSPORT_OFFLINE, transition
+		 * to SDEV_BLOCK is illegal. Calling scsi_target_unblock()
+		 * later is ok though, scsi_internal_device_unblock_nowait()
+		 * treats SDEV_TRANSPORT_OFFLINE like SDEV_BLOCK.
+		 */
+		scsi_target_block(&shost->shost_gendev);
+	res = rport->state != SRP_RPORT_LOST ? i->f->reconnect(rport) : -ENODEV;
+	pr_debug("%s (state %d): transport.reconnect() returned %d\n",
+		 dev_name(&shost->shost_gendev), rport->state, res);
+	if (res == 0) {
+		cancel_delayed_work(&rport->fast_io_fail_work);
+		cancel_delayed_work(&rport->dev_loss_work);
+
+		rport->failed_reconnects = 0;
+		srp_rport_set_state(rport, SRP_RPORT_RUNNING);
+		scsi_target_unblock(&shost->shost_gendev, SDEV_RUNNING);
+		/*
+		 * If the SCSI error handler has offlined one or more devices,
+		 * invoking scsi_target_unblock() won't change the state of
+		 * these devices into running so do that explicitly.
+		 */
+		shost_for_each_device(sdev, shost) {
+			mutex_lock(&sdev->state_mutex);
+			if (sdev->sdev_state == SDEV_OFFLINE)
+				sdev->sdev_state = SDEV_RUNNING;
+			mutex_unlock(&sdev->state_mutex);
+		}
+	} else if (rport->state == SRP_RPORT_RUNNING) {
+		/*
+		 * srp_reconnect_rport() has been invoked with fast_io_fail
+		 * and dev_loss off. Mark the port as failed and start the TL
+		 * failure timers if these had not yet been started.
+		 */
+		__rport_fail_io_fast(rport);
+		__srp_start_tl_fail_timers(rport);
+	} else if (rport->state != SRP_RPORT_BLOCKED) {
+		scsi_target_unblock(&shost->shost_gendev,
+				    SDEV_TRANSPORT_OFFLINE);
+	}
+	mutex_unlock(&rport->mutex);
+
+out:
+	return res;
+}
+EXPORT_SYMBOL(srp_reconnect_rport);
+
+/**
+ * srp_timed_out() - SRP transport intercept of the SCSI timeout EH
+ * @scmd: SCSI command.
+ *
+ * If a timeout occurs while an rport is in the blocked state, ask the SCSI
+ * EH to continue waiting (BLK_EH_RESET_TIMER). Otherwise let the SCSI core
+ * handle the timeout (BLK_EH_DONE).
+ *
+ * Note: This function is called from soft-IRQ context and with the request
+ * queue lock held.
+ */
+enum blk_eh_timer_return srp_timed_out(struct scsi_cmnd *scmd)
+{
+	struct scsi_device *sdev = scmd->device;
+	struct Scsi_Host *shost = sdev->host;
+	struct srp_internal *i = to_srp_internal(shost->transportt);
+	struct srp_rport *rport = shost_to_rport(shost);
+
+	pr_debug("timeout for sdev %s\n", dev_name(&sdev->sdev_gendev));
+	return rport && rport->fast_io_fail_tmo < 0 &&
+		rport->dev_loss_tmo < 0 &&
+		i->f->reset_timer_if_blocked && scsi_device_blocked(sdev) ?
+		BLK_EH_RESET_TIMER : BLK_EH_DONE;
+}
+EXPORT_SYMBOL(srp_timed_out);
+
+static void srp_rport_release(struct device *dev)
+{
+	struct srp_rport *rport = dev_to_rport(dev);
+
+	put_device(dev->parent);
+	kfree(rport);
+}
+
+static int scsi_is_srp_rport(const struct device *dev)
+{
+	return dev->release == srp_rport_release;
+}
+
+static int srp_rport_match(struct attribute_container *cont,
+			   struct device *dev)
+{
+	struct Scsi_Host *shost;
+	struct srp_internal *i;
+
+	if (!scsi_is_srp_rport(dev))
+		return 0;
+
+	shost = dev_to_shost(dev->parent);
+	if (!shost->transportt)
+		return 0;
+	if (shost->transportt->host_attrs.ac.class != &srp_host_class.class)
+		return 0;
+
+	i = to_srp_internal(shost->transportt);
+	return &i->rport_attr_cont.ac == cont;
+}
+
+static int srp_host_match(struct attribute_container *cont, struct device *dev)
+{
+	struct Scsi_Host *shost;
+	struct srp_internal *i;
+
+	if (!scsi_is_host_device(dev))
+		return 0;
+
+	shost = dev_to_shost(dev);
+	if (!shost->transportt)
+		return 0;
+	if (shost->transportt->host_attrs.ac.class != &srp_host_class.class)
+		return 0;
+
+	i = to_srp_internal(shost->transportt);
+	return &i->t.host_attrs.ac == cont;
+}
+
+/**
+ * srp_rport_get() - increment rport reference count
+ * @rport: SRP target port.
+ */
+void srp_rport_get(struct srp_rport *rport)
+{
+	get_device(&rport->dev);
+}
+EXPORT_SYMBOL(srp_rport_get);
+
+/**
+ * srp_rport_put() - decrement rport reference count
+ * @rport: SRP target port.
+ */
+void srp_rport_put(struct srp_rport *rport)
+{
+	put_device(&rport->dev);
+}
+EXPORT_SYMBOL(srp_rport_put);
+
+/**
+ * srp_rport_add - add a SRP remote port to the device hierarchy
+ * @shost:	scsi host the remote port is connected to.
+ * @ids:	The port id for the remote port.
+ *
+ * Publishes a port to the rest of the system.
+ */
+struct srp_rport *srp_rport_add(struct Scsi_Host *shost,
+				struct srp_rport_identifiers *ids)
+{
+	struct srp_rport *rport;
+	struct device *parent = &shost->shost_gendev;
+	struct srp_internal *i = to_srp_internal(shost->transportt);
+	int id, ret;
+
+	rport = kzalloc(sizeof(*rport), GFP_KERNEL);
+	if (!rport)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&rport->mutex);
+
+	device_initialize(&rport->dev);
+
+	rport->dev.parent = get_device(parent);
+	rport->dev.release = srp_rport_release;
+
+	memcpy(rport->port_id, ids->port_id, sizeof(rport->port_id));
+	rport->roles = ids->roles;
+
+	if (i->f->reconnect)
+		rport->reconnect_delay = i->f->reconnect_delay ?
+			*i->f->reconnect_delay : 10;
+	INIT_DELAYED_WORK(&rport->reconnect_work, srp_reconnect_work);
+	rport->fast_io_fail_tmo = i->f->fast_io_fail_tmo ?
+		*i->f->fast_io_fail_tmo : 15;
+	rport->dev_loss_tmo = i->f->dev_loss_tmo ? *i->f->dev_loss_tmo : 60;
+	INIT_DELAYED_WORK(&rport->fast_io_fail_work,
+			  rport_fast_io_fail_timedout);
+	INIT_DELAYED_WORK(&rport->dev_loss_work, rport_dev_loss_timedout);
+
+	id = atomic_inc_return(&to_srp_host_attrs(shost)->next_port_id);
+	dev_set_name(&rport->dev, "port-%d:%d", shost->host_no, id);
+
+	transport_setup_device(&rport->dev);
+
+	ret = device_add(&rport->dev);
+	if (ret) {
+		transport_destroy_device(&rport->dev);
+		put_device(&rport->dev);
+		return ERR_PTR(ret);
+	}
+
+	transport_add_device(&rport->dev);
+	transport_configure_device(&rport->dev);
+
+	return rport;
+}
+EXPORT_SYMBOL_GPL(srp_rport_add);
+
+/**
+ * srp_rport_del  -  remove a SRP remote port
+ * @rport:	SRP remote port to remove
+ *
+ * Removes the specified SRP remote port.
+ */
+void srp_rport_del(struct srp_rport *rport)
+{
+	struct device *dev = &rport->dev;
+
+	transport_remove_device(dev);
+	device_del(dev);
+	transport_destroy_device(dev);
+
+	put_device(dev);
+}
+EXPORT_SYMBOL_GPL(srp_rport_del);
+
+static int do_srp_rport_del(struct device *dev, void *data)
+{
+	if (scsi_is_srp_rport(dev))
+		srp_rport_del(dev_to_rport(dev));
+	return 0;
+}
+
+/**
+ * srp_remove_host  -  tear down a Scsi_Host's SRP data structures
+ * @shost:	Scsi Host that is torn down
+ *
+ * Removes all SRP remote ports for a given Scsi_Host.
+ * Must be called just before scsi_remove_host for SRP HBAs.
+ */
+void srp_remove_host(struct Scsi_Host *shost)
+{
+	device_for_each_child(&shost->shost_gendev, NULL, do_srp_rport_del);
+}
+EXPORT_SYMBOL_GPL(srp_remove_host);
+
+/**
+ * srp_stop_rport_timers - stop the transport layer recovery timers
+ * @rport: SRP remote port for which to stop the timers.
+ *
+ * Must be called after srp_remove_host() and scsi_remove_host(). The caller
+ * must hold a reference on the rport (rport->dev) and on the SCSI host
+ * (rport->dev.parent).
+ */
+void srp_stop_rport_timers(struct srp_rport *rport)
+{
+	mutex_lock(&rport->mutex);
+	if (rport->state == SRP_RPORT_BLOCKED)
+		__rport_fail_io_fast(rport);
+	srp_rport_set_state(rport, SRP_RPORT_LOST);
+	mutex_unlock(&rport->mutex);
+
+	cancel_delayed_work_sync(&rport->reconnect_work);
+	cancel_delayed_work_sync(&rport->fast_io_fail_work);
+	cancel_delayed_work_sync(&rport->dev_loss_work);
+}
+EXPORT_SYMBOL_GPL(srp_stop_rport_timers);
+
+/**
+ * srp_attach_transport  -  instantiate SRP transport template
+ * @ft:		SRP transport class function template
+ */
+struct scsi_transport_template *
+srp_attach_transport(struct srp_function_template *ft)
+{
+	int count;
+	struct srp_internal *i;
+
+	i = kzalloc(sizeof(*i), GFP_KERNEL);
+	if (!i)
+		return NULL;
+
+	i->t.host_size = sizeof(struct srp_host_attrs);
+	i->t.host_attrs.ac.attrs = &i->host_attrs[0];
+	i->t.host_attrs.ac.class = &srp_host_class.class;
+	i->t.host_attrs.ac.match = srp_host_match;
+	i->host_attrs[0] = NULL;
+	transport_container_register(&i->t.host_attrs);
+
+	i->rport_attr_cont.ac.attrs = &i->rport_attrs[0];
+	i->rport_attr_cont.ac.class = &srp_rport_class.class;
+	i->rport_attr_cont.ac.match = srp_rport_match;
+
+	count = 0;
+	i->rport_attrs[count++] = &dev_attr_port_id;
+	i->rport_attrs[count++] = &dev_attr_roles;
+	if (ft->has_rport_state) {
+		i->rport_attrs[count++] = &dev_attr_state;
+		i->rport_attrs[count++] = &dev_attr_fast_io_fail_tmo;
+		i->rport_attrs[count++] = &dev_attr_dev_loss_tmo;
+	}
+	if (ft->reconnect) {
+		i->rport_attrs[count++] = &dev_attr_reconnect_delay;
+		i->rport_attrs[count++] = &dev_attr_failed_reconnects;
+	}
+	if (ft->rport_delete)
+		i->rport_attrs[count++] = &dev_attr_delete;
+	i->rport_attrs[count++] = NULL;
+	BUG_ON(count > ARRAY_SIZE(i->rport_attrs));
+
+	transport_container_register(&i->rport_attr_cont);
+
+	i->f = ft;
+
+	return &i->t;
+}
+EXPORT_SYMBOL_GPL(srp_attach_transport);
+
+/**
+ * srp_release_transport  -  release SRP transport template instance
+ * @t:		transport template instance
+ */
+void srp_release_transport(struct scsi_transport_template *t)
+{
+	struct srp_internal *i = to_srp_internal(t);
+
+	transport_container_unregister(&i->t.host_attrs);
+	transport_container_unregister(&i->rport_attr_cont);
+
+	kfree(i);
+}
+EXPORT_SYMBOL_GPL(srp_release_transport);
+
+static __init int srp_transport_init(void)
+{
+	int ret;
+
+	ret = transport_class_register(&srp_host_class);
+	if (ret)
+		return ret;
+	ret = transport_class_register(&srp_rport_class);
+	if (ret)
+		goto unregister_host_class;
+
+	return 0;
+unregister_host_class:
+	transport_class_unregister(&srp_host_class);
+	return ret;
+}
+
+static void __exit srp_transport_exit(void)
+{
+	transport_class_unregister(&srp_host_class);
+	transport_class_unregister(&srp_rport_class);
+}
+
+MODULE_AUTHOR("FUJITA Tomonori");
+MODULE_DESCRIPTION("SRP Transport Attributes");
+MODULE_LICENSE("GPL");
+
+module_init(srp_transport_init);
+module_exit(srp_transport_exit);