scsi_dh: Add ability to set parameters for scsi device handler

Index: linux-2.6.31-rc1/include/scsi/scsi_device.h
===================================================================
@@ -187,6 +187,7 @@ struct scsi_device_handler {
 	void (*detach)(struct scsi_device *);
 	int (*activate)(struct scsi_device *);
 	int (*prep_fn)(struct scsi_device *, struct request *);
+	int (*set_params)(struct scsi_device *, const char *);
 };
 
 struct scsi_dh_data {

Index: linux-2.6.31-rc1/include/scsi/scsi_dh.h
===================================================================
@@ -60,6 +60,7 @@ extern int scsi_dh_activate(struct reque
 extern int scsi_dh_handler_exist(const char *);
 extern int scsi_dh_attach(struct request_queue *, const char *);
 extern void scsi_dh_detach(struct request_queue *);
+extern int scsi_dh_set_params(struct request_queue *, const char *);
 #else
 static inline int scsi_dh_activate(struct request_queue *req)
 {

@@ -77,4 +78,8 @@ static inline void scsi_dh_detach(struct
 {
 	return;
 }
+static inline int scsi_dh_set_params(struct request_queue *req, const char *params)
+{
+	return -SCSI_DH_NOSYS;
+}
 #endif

Index: linux-2.6.31-rc1/drivers/scsi/device_handler/scsi_dh.c
===================================================================
@@ -449,6 +449,39 @@ int scsi_dh_activate(struct request_queu
 EXPORT_SYMBOL_GPL(scsi_dh_activate);
 
 /*
+ * scsi_dh_set_params - set the parameters for the device as per the
+ *      string specified in params.
+ * @q - Request queue that is associated with the scsi_device for
+ *      which the parameters to be set.
+ * @params - parameters in the following format
+ *      "no_of_params\0param1\0param2\0param3\0...\0"
+ *      for example, string for 2 parameters with value 10 and 21
+ *      is specified as "2\010\021\0".
+ */
+int scsi_dh_set_params(struct request_queue *q, const char *params)
+{
+	int err = -SCSI_DH_NOSYS;
+	unsigned long flags;
+	struct scsi_device *sdev;
+	struct scsi_device_handler *scsi_dh = NULL;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	sdev = q->queuedata;
+	if (sdev && sdev->scsi_dh_data)
+		scsi_dh = sdev->scsi_dh_data->scsi_dh;
+	if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
+		err = 0;
+	spin_unlock_irqrestore(q->queue_lock, flags);
+
+	if (err)
+		return err;
+	err = scsi_dh->set_params(sdev, params);
+	put_device(&sdev->sdev_gendev);
+	return err;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_set_params);
+
+/*
  * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
  *	the given name. FALSE(0) otherwise.
  * @name - name of the device handler.

Index: linux-2.6.31-rc3/drivers/scsi/device_handler/scsi_dh_emc.c
===================================================================
@@ -561,6 +561,61 @@ done:
 
 	return result;
 }
+/*
+ * params - parameters in the following format
+ *      "no_of_params\0param1\0param2\0param3\0...\0"
+ *      for example, string for 2 parameters with value 10 and 21
+ *      is specified as "2\010\021\0".
+ */
+static int clariion_set_params(struct scsi_device *sdev, const char *params)
+{
+	struct clariion_dh_data *csdev = get_clariion_data(sdev);
+	unsigned int hr = 0, st = 0, argc;
+	const char *p = params;
+	int result = SCSI_DH_OK;
+
+	if ((sscanf(params, "%u", &argc) != 1) || (argc != 2))
+		return -EINVAL;
+
+	while (*p++)
+		;
+	if ((sscanf(p, "%u", &st) != 1) || (st > 1))
+		return -EINVAL;
+
+	while (*p++)
+		;
+	if ((sscanf(p, "%u", &hr) != 1) || (hr > 1))
+		return -EINVAL;
+
+	if (st)
+		csdev->flags |= CLARIION_SHORT_TRESPASS;
+	else
+		csdev->flags &= ~CLARIION_SHORT_TRESPASS;
+
+	if (hr)
+		csdev->flags |= CLARIION_HONOR_RESERVATIONS;
+	else
+		csdev->flags &= ~CLARIION_HONOR_RESERVATIONS;
+
+	/*
+	 * If this path is owned, we have to send a trespass command
+	 * with the new parameters. If not, simply return. Next trespass
+	 * command would use the parameters.
+	 */
+	if (csdev->lun_state != CLARIION_LUN_OWNED)
+		goto done;
+
+	csdev->lun_state = CLARIION_LUN_UNINITIALIZED;
+	result = send_trespass_cmd(sdev, csdev);
+	if (result != SCSI_DH_OK)
+		goto done;
+
+	/* Update status */
+	result = clariion_send_inquiry(sdev, csdev);
+
+done:
+	return result;
+}
 
 static const struct scsi_dh_devlist clariion_dev_list[] = {
 	{"DGC", "RAID"},

@@ -581,11 +636,9 @@ static struct scsi_device_handler clarii
 	.check_sense	= clariion_check_sense,
 	.activate	= clariion_activate,
 	.prep_fn	= clariion_prep_fn,
+	.set_params	= clariion_set_params,
 };
 
-/*
- * TODO: need some interface so we can set trespass values
- */
 static int clariion_bus_attach(struct scsi_device *sdev)
 {
 	struct scsi_dh_data *scsi_dh_data;

Index: linux-2.6.31-rc1/drivers/md/dm-mpath.c
===================================================================
@@ -64,6 +64,7 @@ struct multipath {
 	spinlock_t lock;
 
 	const char *hw_handler_name;
+	char *hw_handler_params;
 	unsigned nr_priority_groups;
 	struct list_head priority_groups;
 	unsigned pg_init_required;	/* pg_init needs calling? */

@@ -219,6 +220,7 @@ static void free_multipath(struct multip
 	}
 
 	kfree(m->hw_handler_name);
+	kfree(m->hw_handler_params);
 	mempool_destroy(m->mpio_pool);
 	kfree(m);
 }

@@ -615,6 +617,17 @@ static struct pgpath *parse_path(struct
 			dm_put_device(ti, p->path.dev);
 			goto bad;
 		}
+
+		if (m->hw_handler_params) {
+			r = scsi_dh_set_params(q, m->hw_handler_params);
+			if (r < 0) {
+				ti->error = "unable to set hardware "
+							"handler parameters";
+				scsi_dh_detach(q);
+				dm_put_device(ti, p->path.dev);
+				goto bad;
+			}
+		}
 	}
 
 	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);

@@ -705,6 +718,7 @@ static struct priority_group *parse_prio
 static int parse_hw_handler(struct arg_set *as, struct multipath *m)
 {
 	unsigned hw_argc;
+	int ret;
 	struct dm_target *ti = m->ti;
 
 	static struct param _params[] = {

@@ -726,17 +740,33 @@ static int parse_hw_handler(struct arg_s
 	request_module("scsi_dh_%s", m->hw_handler_name);
 	if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
 		ti->error = "unknown hardware handler type";
-		kfree(m->hw_handler_name);
-		m->hw_handler_name = NULL;
-		return -EINVAL;
+		ret = -EINVAL;
+		goto fail;
 	}
 
-	if (hw_argc > 1)
-		DMWARN("Ignoring user-specified arguments for "
-		       "hardware handler \"%s\"", m->hw_handler_name);
+	if (hw_argc > 1) {
+		char *p;
+		int i, j, len = 4;
+
+		for (i = 0; i <= hw_argc - 2; i++)
+			len += strlen(as->argv[i]) + 1;
+		p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
+		if (!p) {
+			ti->error = "memory allocation failed";
+			ret = -ENOMEM;
+			goto fail;
+		}
+		j = sprintf(p, "%d", hw_argc - 1);
+		for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
+			j = sprintf(p, "%s", as->argv[i]);
+	}
 	consume(as, hw_argc - 1);
 
 	return 0;
+fail:
+	kfree(m->hw_handler_name);
+	m->hw_handler_name = NULL;
+	return ret;
 }
 
 static int parse_features(struct arg_set *as, struct multipath *m)