IB/srp: Allow SRP disconnect through sysfs

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

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

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

4 files changed, 46 insertions, 1 deletions

diff --git a/Documentation/ABI/stable/sysfs-transport-srp b/Documentation/ABI/stable/sysfs-transport-srp
index 7b0d4a5350f1..b36fb0dc13c8 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 84d9298ed989..d5088ce78290 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -549,6 +549,13 @@ 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;
@@ -1958,6 +1965,8 @@ 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);
@@ -2524,6 +2533,7 @@ 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 0d85f797141f..f379c7f3034c 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 9c60ca1c08c5..ff0f04ac91aa 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);