[PATCH 00/19, v5] Make ib_srp better suited for H.A. purposes

[PATCH 00/19, v5] Make ib_srp better suited for H.A. purposes

[Bart Van Assche]

This patch series makes the ib_srp driver better suited for use in a
H.A. setup because:
- multipathd is notified faster about transport layer failures.
- Transport layer failures reliably result in SCSI host removal.
- Switchover can be triggered explicitly by deleting an initiator
   device.
- Disconnecting from a target without unloading ib_srp is now possible.

This patch series is also available here:
http://github.com/bvanassche/linux/commits/srp-ha
And a backport of this patch series to kernels 3.6 and before is 
available here: http://github.com/bvanassche/ib_srp-backport.

Changes since v4:
- Added a patch for removing SCSI devices upon a port down event

Changes since v3:
- Restored the dev_loss_tmo and fast_io_fail_tmo sysfs attributes.
- Included a patch to fix an ib_srp crash that could be triggered by
   cable pulling.

Changes since v2:
- Addressed the v2 review comments.
- Dropped the patches that have already been merged.
- Dropped the patches for integration with multipathd.
- Dropped the micro-optimization of the IB completion handlers.

The individual patches are:
0001-ib_srp-Enlarge-block-layer-timeout.patch
0002-ib_srp-Eliminate-state-SRP_TARGET_CONNECTING.patch
0003-ib_srp-Introduce-srp_handle_qp_err.patch
0004-ib_srp-Suppress-superfluous-error-messages.patch
0005-ib_srp-Avoid-that-SCSI-error-handling-causes-trouble.patch
0006-ib_srp-Introduce-the-helper-function-srp_remove_targ.patch
0007-ib_srp-Eliminate-state-SRP_TARGET_DEAD.patch
0008-ib_srp-Keep-processing-commands-during-host-removal.patch
0009-ib_srp-Make-srp_disconnect_target-wait-for-IB-comple.patch
0010-ib_srp-Document-sysfs-attributes.patch
0011-srp_transport-Fix-atttribute-registration.patch
0012-srp_transport-Simplify-attribute-initialization-code.patch
0013-srp_transport-Document-sysfs-attributes.patch
0014-ib_srp-Allow-SRP-disconnect-through-sysfs.patch
0015-ib_srp-Maintain-a-single-connection-per-I_T-nexus.patch
0016-srp_transport-Add-transport-layer-error-handling.patch
0017-ib_srp-Add-dev_loss_tmo-support.patch
0018-ib_srp-Remove-SCSI-devices-upon-port-down-event.patch
0019-scsi_transport_srp-Fail-I-O-faster.patch

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[PATCH 11/19] srp_transport: Fix attribute registration

[Bart Van Assche]

Register transport attributes after the attribute array has been
set up instead of before. The current code can trigger a race
condition because the code reading the attribute array can run
on another thread than the code that initialized that array.
Make sure that any code reading the attribute array will see all
values written into that array.

Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: David Dillow <dillowda@ornl.gov>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_transport_srp.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index 21a045e..07c4394 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -324,13 +324,14 @@ srp_attach_transport(struct srp_function_template *ft)
 	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;
-	transport_container_register(&i->rport_attr_cont);
 
 	count = 0;
 	SETUP_RPORT_ATTRIBUTE_RD(port_id);
 	SETUP_RPORT_ATTRIBUTE_RD(roles);
 	i->rport_attrs[count] = NULL;
 
+	transport_container_register(&i->rport_attr_cont);
+
 	i->f = ft;
 
 	return &i->t;
-- 
1.7.10.4

[PATCH 12/19] srp_transport: Simplify attribute initialization code

[Bart Van Assche]

Eliminate the private_rport_attrs[] array and the SETUP_*() macros
used to set up that array since the information in that array
duplicates the information in the static device attributes. Also,
verify whether SRP_RPORT_ATTRS is large enough since it is easy
to forget to update that macro when adding new attributes.

Cc: FUJITA Tomonori <fujita.tomonori-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org>
Cc: Robert Jennings <rcj-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Cc: David Dillow <dillowda-1Heg1YXhbW8@public.gmane.org>
Cc: Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
Signed-off-by: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
---
 drivers/scsi/scsi_transport_srp.c |   26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index 07c4394..0d85f79 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -47,7 +47,6 @@ struct srp_internal {
 	struct device_attribute *host_attrs[SRP_HOST_ATTRS + 1];
 
 	struct device_attribute *rport_attrs[SRP_RPORT_ATTRS + 1];
-	struct device_attribute private_rport_attrs[SRP_RPORT_ATTRS];
 	struct transport_container rport_attr_cont;
 };
 
@@ -72,24 +71,6 @@ static DECLARE_TRANSPORT_CLASS(srp_host_class, "srp_host", srp_host_setup,
 static DECLARE_TRANSPORT_CLASS(srp_rport_class, "srp_remote_ports",
 			       NULL, NULL, NULL);
 
-#define SETUP_TEMPLATE(attrb, field, perm, test, ro_test, ro_perm)	\
-	i->private_##attrb[count] = dev_attr_##field;		\
-	i->private_##attrb[count].attr.mode = perm;			\
-	if (ro_test) {							\
-		i->private_##attrb[count].attr.mode = ro_perm;		\
-		i->private_##attrb[count].store = NULL;			\
-	}								\
-	i->attrb[count] = &i->private_##attrb[count];			\
-	if (test)							\
-		count++
-
-#define SETUP_RPORT_ATTRIBUTE_RD(field)					\
-	SETUP_TEMPLATE(rport_attrs, field, S_IRUGO, 1, 0, 0)
-
-#define SETUP_RPORT_ATTRIBUTE_RW(field)					\
-	SETUP_TEMPLATE(rport_attrs, field, S_IRUGO | S_IWUSR,		\
-		       1, 1, S_IRUGO)
-
 #define SRP_PID(p) \
 	(p)->port_id[0], (p)->port_id[1], (p)->port_id[2], (p)->port_id[3], \
 	(p)->port_id[4], (p)->port_id[5], (p)->port_id[6], (p)->port_id[7], \
@@ -326,9 +307,10 @@ srp_attach_transport(struct srp_function_template *ft)
 	i->rport_attr_cont.ac.match = srp_rport_match;
 
 	count = 0;
-	SETUP_RPORT_ATTRIBUTE_RD(port_id);
-	SETUP_RPORT_ATTRIBUTE_RD(roles);
-	i->rport_attrs[count] = NULL;
+	i->rport_attrs[count++] = &dev_attr_port_id;
+	i->rport_attrs[count++] = &dev_attr_roles;
+	i->rport_attrs[count++] = NULL;
+	BUG_ON(count > ARRAY_SIZE(i->rport_attrs));
 
 	transport_container_register(&i->rport_attr_cont);
 
-- 
1.7.10.4

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[PATCH 13/19] srp_transport: Document sysfs attributes

[Bart Van Assche]

Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Cc: David Dillow <dillowda@ornl.gov>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 Documentation/ABI/stable/sysfs-transport-srp |   12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 Documentation/ABI/stable/sysfs-transport-srp

diff --git a/Documentation/ABI/stable/sysfs-transport-srp b/Documentation/ABI/stable/sysfs-transport-srp
new file mode 100644
index 0000000..7b0d4a5
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-transport-srp
@@ -0,0 +1,12 @@
+What:		/sys/class/srp_remote_ports/port-<h>:<n>/port_id
+Date:		June 27, 2007
+KernelVersion:	2.6.24
+Contact:	linux-scsi@vger.kernel.org
+Description:	16-byte local SRP port identifier in hexadecimal format. An
+		example: 4c:49:4e:55:58:20:56:49:4f:00:00:00:00:00:00:00.
+
+What:		/sys/class/srp_remote_ports/port-<h>:<n>/roles
+Date:		June 27, 2007
+KernelVersion:	2.6.24
+Contact:	linux-scsi@vger.kernel.org
+Description:	Role of the remote port. Either "SRP Initiator" or "SRP Target".
-- 
1.7.10.4

[PATCH 14/19] ib_srp: Allow SRP disconnect through sysfs

[Bart Van Assche]

Make it possible to disconnect the IB RC connection used by the
SRP protocol to communicate with a target.

Let the SRP transport layer create a sysfs "delete" attribute for
initiator drivers that support this functionality.

Cc: David Dillow <dillowda@ornl.gov>
Cc: Roland Dreier <roland@purestorage.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 Documentation/ABI/stable/sysfs-transport-srp |    7 +++++++
 drivers/infiniband/ulp/srp/ib_srp.c          |   10 ++++++++++
 drivers/scsi/scsi_transport_srp.c            |   22 +++++++++++++++++++++-
 include/scsi/scsi_transport_srp.h            |    8 ++++++++
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/stable/sysfs-transport-srp b/Documentation/ABI/stable/sysfs-transport-srp
index 7b0d4a5..b36fb0d 100644
--- a/Documentation/ABI/stable/sysfs-transport-srp
+++ b/Documentation/ABI/stable/sysfs-transport-srp
@@ -1,3 +1,10 @@
+What:		/sys/class/srp_remote_ports/port-<h>:<n>/delete
+Date:		June 1, 2012
+KernelVersion:	3.7
+Contact:	linux-scsi@vger.kernel.org, linux-rdma@vger.kernel.org
+Description:	Instructs an SRP initiator to disconnect from a target and to
+		remove all LUNs imported from that target.
+
 What:		/sys/class/srp_remote_ports/port-<h>:<n>/port_id
 Date:		June 27, 2007
 KernelVersion:	2.6.24
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 58d19a2..96e9bc2 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -609,6 +609,13 @@ static void srp_remove_work(struct work_struct *work)
 	srp_remove_target(target);
 }
 
+static void srp_rport_delete(struct srp_rport *rport)
+{
+	struct srp_target_port *target = rport->lld_data;
+
+	srp_queue_remove_work(target);
+}
+
 static int srp_connect_target(struct srp_target_port *target)
 {
 	int retries = 3;
@@ -2034,6 +2041,8 @@ static int srp_add_target(struct srp_host *host, struct srp_target_port *target)
 		return PTR_ERR(rport);
 	}
 
+	rport->lld_data = target;
+
 	spin_lock(&host->target_lock);
 	list_add_tail(&target->list, &host->target_list);
 	spin_unlock(&host->target_lock);
@@ -2601,6 +2610,7 @@ static void srp_remove_one(struct ib_device *device)
 }
 
 static struct srp_function_template ib_srp_transport_functions = {
+	.rport_delete		 = srp_rport_delete,
 };
 
 static int __init srp_init_module(void)
diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index 0d85f79..f379c7f 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -38,7 +38,7 @@ struct srp_host_attrs {
 #define to_srp_host_attrs(host)	((struct srp_host_attrs *)(host)->shost_data)
 
 #define SRP_HOST_ATTRS 0
-#define SRP_RPORT_ATTRS 2
+#define SRP_RPORT_ATTRS 3
 
 struct srp_internal {
 	struct scsi_transport_template t;
@@ -116,6 +116,24 @@ show_srp_rport_roles(struct device *dev, struct device_attribute *attr,
 
 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 void srp_rport_release(struct device *dev)
 {
 	struct srp_rport *rport = dev_to_rport(dev);
@@ -309,6 +327,8 @@ srp_attach_transport(struct srp_function_template *ft)
 	count = 0;
 	i->rport_attrs[count++] = &dev_attr_port_id;
 	i->rport_attrs[count++] = &dev_attr_roles;
+	if (ft->rport_delete)
+		i->rport_attrs[count++] = &dev_attr_delete;
 	i->rport_attrs[count++] = NULL;
 	BUG_ON(count > ARRAY_SIZE(i->rport_attrs));
 
diff --git a/include/scsi/scsi_transport_srp.h b/include/scsi/scsi_transport_srp.h
index 9c60ca1..ff0f04a 100644
--- a/include/scsi/scsi_transport_srp.h
+++ b/include/scsi/scsi_transport_srp.h
@@ -14,13 +14,21 @@ struct srp_rport_identifiers {
 };
 
 struct srp_rport {
+	/* for initiator and target drivers */
+
 	struct device dev;
 
 	u8 port_id[16];
 	u8 roles;
+
+	/* for initiator drivers */
+
+	void *lld_data;	/* LLD private data */
 };
 
 struct srp_function_template {
+	/* for initiator drivers */
+	void (*rport_delete)(struct srp_rport *rport);
 	/* for target drivers */
 	int (* tsk_mgmt_response)(struct Scsi_Host *, u64, u64, int);
 	int (* it_nexus_response)(struct Scsi_Host *, u64, int);
-- 
1.7.10.4

[PATCH 16/19] srp_transport: Add transport layer error handling

[Bart Van Assche]

Add the necessary functions in the SRP transport module to allow
an SRP initiator driver to implement transport error handling.
This includes:
- Support for implementing fast_io_fail_tmo, the time that should
  elapse after having detected a transport layer problem and
  before failing I/O.
- Support for implementing dev_loss_tmo, the time that should
  elapse after having detected a transport layer problem and
  before removing a remote port.

Cc: FUJITA Tomonori <fujita.tomonori-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org>
Cc: Robert Jennings <rcj-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Cc: David Dillow <dillowda-1Heg1YXhbW8@public.gmane.org>
Signed-off-by: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
---
 Documentation/ABI/stable/sysfs-transport-srp |   17 +++
 drivers/scsi/scsi_transport_srp.c            |  192 +++++++++++++++++++++++++-
 include/scsi/scsi_transport_srp.h            |   10 +-
 3 files changed, 216 insertions(+), 3 deletions(-)

diff --git a/Documentation/ABI/stable/sysfs-transport-srp b/Documentation/ABI/stable/sysfs-transport-srp
index b36fb0d..2f14a5b 100644
--- a/Documentation/ABI/stable/sysfs-transport-srp
+++ b/Documentation/ABI/stable/sysfs-transport-srp
@@ -5,6 +5,23 @@ Contact:	linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
 Description:	Instructs an SRP initiator to disconnect from a target and to
 		remove all LUNs imported from that target.
 
+What:		/sys/class/srp_remote_ports/port-<h>:<n>/dev_loss_tmo
+Date:		January 1, 2012
+KernelVersion:	3.7
+Contact:	linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
+Description:	Number of seconds the SCSI layer will wait after a transport
+		layer error has been observed before removing a target port.
+		Zero means immediate removal.
+
+What:		/sys/class/srp_remote_ports/port-<h>:<n>/fast_io_fail_tmo
+Date:		January 1, 2012
+KernelVersion:	3.7
+Contact:	linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
+Description:	Number of seconds the SCSI layer will wait after a transport
+		layer error has been observed before failing I/O. Zero means
+		immediate removal. A negative value will disable this
+		behavior.
+
 What:		/sys/class/srp_remote_ports/port-<h>:<n>/port_id
 Date:		June 27, 2007
 KernelVersion:	2.6.24
diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index f379c7f..8b452c6 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -30,6 +30,7 @@
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_transport.h>
 #include <scsi/scsi_transport_srp.h>
+#include "scsi_priv.h"
 #include "scsi_transport_srp_internal.h"
 
 struct srp_host_attrs {
@@ -38,7 +39,7 @@ struct srp_host_attrs {
 #define to_srp_host_attrs(host)	((struct srp_host_attrs *)(host)->shost_data)
 
 #define SRP_HOST_ATTRS 0
-#define SRP_RPORT_ATTRS 3
+#define SRP_RPORT_ATTRS 5
 
 struct srp_internal {
 	struct scsi_transport_template t;
@@ -54,6 +55,10 @@ struct srp_internal {
 
 #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 srp_host_setup(struct transport_container *tc, struct device *dev,
 			  struct device *cdev)
@@ -134,6 +139,175 @@ static ssize_t store_srp_rport_delete(struct device *dev,
 
 static DEVICE_ATTR(delete, S_IWUSR, NULL, store_srp_rport_delete);
 
+/**
+ * srp_tmo_valid() - Check timeout combination validity.
+ *
+ * If no fast I/O fail timeout has been configured then the device loss timeout
+ * must be below SCSI_DEVICE_BLOCK_MAX_TIMEOUT. If a fast I/O fail timeout has
+ * been configured then it must be below the device loss timeout.
+ */
+static int srp_tmo_valid(int fast_io_fail_tmo, unsigned dev_loss_tmo)
+{
+	return (fast_io_fail_tmo < 0 &&
+		dev_loss_tmo <= SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
+		|| (0 <= fast_io_fail_tmo &&
+		    fast_io_fail_tmo < dev_loss_tmo &&
+		    dev_loss_tmo < ULONG_MAX / HZ) ? 0 : -EINVAL;
+}
+
+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);
+
+	if (rport->fast_io_fail_tmo >= 0)
+		return sprintf(buf, "%d\n", rport->fast_io_fail_tmo);
+	else
+		return sprintf(buf, "off\n");
+}
+
+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);
+	char ch[16];
+	int res;
+	int fast_io_fail_tmo;
+
+	if (count >= 3 && memcmp(buf, "off", 3) == 0) {
+		fast_io_fail_tmo = -1;
+	} else {
+		sprintf(ch, "%.*s", min_t(int, sizeof(ch) - 1, count), buf);
+		res = kstrtoint(ch, 0, &fast_io_fail_tmo);
+		if (res)
+			goto out;
+	}
+	res = srp_tmo_valid(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 sprintf(buf, "%u\n", 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);
+	char ch[16];
+	int res;
+	unsigned dev_loss_tmo;
+
+	sprintf(ch, "%.*s", min_t(int, sizeof(ch) - 1, count), buf);
+	res = kstrtouint(ch, 0, &dev_loss_tmo);
+	if (res)
+		goto out;
+	res = srp_tmo_valid(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);
+
+/**
+ * rport_fast_io_fail_timedout() - Fast I/O failure timeout handler.
+ *
+ * Unblocks the SCSI host.
+ */
+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;
+	struct srp_internal *i;
+
+	pr_err("SRP transport: fast_io_fail_tmo (%ds) expired - unblocking %s.\n",
+	       rport->fast_io_fail_tmo, dev_name(&rport->dev));
+
+	shost = rport_to_shost(rport);
+	i = to_srp_internal(shost->transportt);
+	/* Involve the LLDD if possible to terminate all io on the rport. */
+	if (i->f->terminate_rport_io)
+		i->f->terminate_rport_io(rport);
+
+	scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE);
+}
+
+/**
+ * rport_dev_loss_timedout() - Device loss timeout handler.
+ *
+ * Note: rport->ft->rport_delete must either unblock the SCSI host or schedule
+ * SCSI host removal.
+ */
+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;
+	struct srp_internal *i;
+
+	pr_err("SRP transport: dev_loss_tmo (%ds) expired - removing %s.\n",
+	       rport->dev_loss_tmo, dev_name(&rport->dev));
+
+	shost = rport_to_shost(rport);
+	i = to_srp_internal(shost->transportt);
+	BUG_ON(!i->f);
+	BUG_ON(!i->f->rport_delete);
+
+	i->f->rport_delete(rport);
+}
+
+/**
+ * srp_start_tl_fail_timers() - Start the transport layer failure timers.
+ * @rport: rport on which to start the transport layer failure timers.
+ * @elapsed: Time in jiffies that has already elapsed since the failure.
+ *
+ * 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, int elapsed)
+{
+	if (rport->fast_io_fail_tmo >= 0)
+		queue_delayed_work(system_long_wq, &rport->fast_io_fail_work,
+				   max_t(long, 1UL * rport->fast_io_fail_tmo
+					 * HZ - elapsed, 0));
+	queue_delayed_work(system_long_wq, &rport->dev_loss_work,
+		max_t(long, 1UL * rport->dev_loss_tmo * HZ - elapsed, 0));
+}
+EXPORT_SYMBOL(srp_start_tl_fail_timers);
+
+void srp_stop_tl_fail_timers(struct srp_rport *rport)
+{
+	cancel_delayed_work_sync(&rport->fast_io_fail_work);
+	cancel_delayed_work_sync(&rport->dev_loss_work);
+}
+EXPORT_SYMBOL(srp_stop_tl_fail_timers);
+
 static void srp_rport_release(struct device *dev)
 {
 	struct srp_rport *rport = dev_to_rport(dev);
@@ -210,6 +384,12 @@ struct srp_rport *srp_rport_add(struct Scsi_Host *shost,
 	memcpy(rport->port_id, ids->port_id, sizeof(rport->port_id));
 	rport->roles = ids->roles;
 
+	rport->fast_io_fail_tmo = -1;
+	rport->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);
 
@@ -252,6 +432,11 @@ void srp_rport_del(struct srp_rport *rport)
 	struct device *dev = &rport->dev;
 	struct Scsi_Host *shost = dev_to_shost(dev->parent);
 
+	device_remove_file(dev, &dev_attr_fast_io_fail_tmo);
+	device_remove_file(dev, &dev_attr_dev_loss_tmo);
+	srp_stop_tl_fail_timers(rport);
+	scsi_target_unblock(rport->dev.parent, SDEV_RUNNING);
+
 	if (shost->active_mode & MODE_TARGET &&
 	    rport->roles == SRP_RPORT_ROLE_INITIATOR)
 		srp_tgt_it_nexus_destroy(shost, (unsigned long)rport);
@@ -327,8 +512,11 @@ srp_attach_transport(struct srp_function_template *ft)
 	count = 0;
 	i->rport_attrs[count++] = &dev_attr_port_id;
 	i->rport_attrs[count++] = &dev_attr_roles;
-	if (ft->rport_delete)
+	if (ft->rport_delete) {
+		i->rport_attrs[count++] = &dev_attr_dev_loss_tmo;
+		i->rport_attrs[count++] = &dev_attr_fast_io_fail_tmo;
 		i->rport_attrs[count++] = &dev_attr_delete;
+	}
 	i->rport_attrs[count++] = NULL;
 	BUG_ON(count > ARRAY_SIZE(i->rport_attrs));
 
diff --git a/include/scsi/scsi_transport_srp.h b/include/scsi/scsi_transport_srp.h
index ff0f04a..eb996db 100644
--- a/include/scsi/scsi_transport_srp.h
+++ b/include/scsi/scsi_transport_srp.h
@@ -23,11 +23,17 @@ struct srp_rport {
 
 	/* for initiator drivers */
 
-	void *lld_data;	/* LLD private data */
+	void			*lld_data;	/* LLD private data */
+
+	int			fast_io_fail_tmo;
+	unsigned		dev_loss_tmo;
+	struct delayed_work	fast_io_fail_work;
+	struct delayed_work	dev_loss_work;
 };
 
 struct srp_function_template {
 	/* for initiator drivers */
+	void (*terminate_rport_io)(struct srp_rport *rport);
 	void (*rport_delete)(struct srp_rport *rport);
 	/* for target drivers */
 	int (* tsk_mgmt_response)(struct Scsi_Host *, u64, u64, int);
@@ -41,6 +47,8 @@ extern void srp_release_transport(struct scsi_transport_template *);
 extern struct srp_rport *srp_rport_add(struct Scsi_Host *,
 				       struct srp_rport_identifiers *);
 extern void srp_rport_del(struct srp_rport *);
+extern void srp_start_tl_fail_timers(struct srp_rport *rport, int elapsed);
+extern void srp_stop_tl_fail_timers(struct srp_rport *rport);
 
 extern void srp_remove_host(struct Scsi_Host *);
 
-- 
1.7.10.4

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