lib/nvmf: add the nvmf_get_targets rpc.

Also update the changelog for the previous few changes.

Change-Id: I79ac330b4992ccc3e41fd1643b09128c6de6c86d
Signed-off-by: Seth Howell <seth.howell@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/468391
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

CHANGELOG.md

@@ -21,6 +21,17 @@ a null name parameter and will return the only available target.
 The majority of the NVMe-oF RPCs now accept an optional tgt_name parameter. This will
 allow those RPCs to work with applications that create more than one target.
 
+Three new NVMe-oF RPCs have been added `nvmf_create_target`, `nvmf_delete_target`, and
+`nvmf_get_targets`. These new RPCs provide a basic interface for managing multiple target
+objects. In SPDK the target object defines a unique discovery service. As of this release,
+these RPCs are not intended to be used with the in-tree SPDK target applications, spdk_tgt and
+nvmf_tgt, which use a single, global target structure. As such, they are not included in scripts/rpc.py
+
+Three new header functions have also been added to help deal with multiple targets.
+`spdk_nvmf_tgt_get_name` takes a target pointer as an argument and returns its human readable name.
+`spdk_nvmf_get_first_target` takes no arguments and returns the first target in the global list.
+`spdk_nvmf_get_next_tgt` takes a target pointer as an argument and returns the next one in the global list.
+
 ### bdev
 
 A new spdk_bdev_open_ext function has been added and spdk_bdev_open function has been deprecated.

lib/nvmf/nvmf_rpc.c

@@ -1501,6 +1501,36 @@ spdk_rpc_nvmf_delete_target(struct spdk_jsonrpc_request *request,
 }
 SPDK_RPC_REGISTER("nvmf_delete_target", spdk_rpc_nvmf_delete_target, SPDK_RPC_RUNTIME);
 
+static void
+spdk_rpc_nvmf_get_targets(struct spdk_jsonrpc_request *request,
+			  const struct spdk_json_val *params)
+{
+	struct spdk_json_write_ctx	*w;
+	struct spdk_nvmf_tgt		*tgt;
+	const char			*name;
+
+	if (params != NULL) {
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS,
+						 "nvmf_get_targets has no parameters.");
+		return;
+	}
+
+	w = spdk_jsonrpc_begin_result(request);
+	spdk_json_write_array_begin(w);
+
+	tgt = spdk_nvmf_get_first_tgt();
+
+	while (tgt != NULL) {
+		name = spdk_nvmf_tgt_get_name(tgt);
+		spdk_json_write_string(w, name);
+		tgt = spdk_nvmf_get_next_tgt(tgt);
+	}
+
+	spdk_json_write_array_end(w);
+	spdk_jsonrpc_end_result(request, w);
+}
+SPDK_RPC_REGISTER("nvmf_get_targets", spdk_rpc_nvmf_get_targets, SPDK_RPC_RUNTIME);
+
 struct nvmf_rpc_create_transport_ctx {
 	char				*trtype;
 	char				*tgt_name;

scripts/rpc/nvmf.py

@@ -75,6 +75,16 @@ def nvmf_delete_target(client,
     return client.call("nvmf_delete_target", params)
 
 
+def nvmf_get_targets(client):
+    """Get a list of all the NVMe-oF targets in this application
+
+    Returns:
+        An array of target names.
+    """
+
+    return client.call("nvmf_get_targets")
+
+
 def nvmf_create_transport(client,
                           trtype,
                           tgt_name=None,