ublk: turn ublk_start_disk in async

Since ublk_start_disk internally runs ublk_ctrl_cmd
asynchorously, the result should be returned after the
whole process of ublk_start_disk is completed.
Add a callback into ublk_start_disk parameter, and change
rpc_ublk_start_disk to send response in callback.

Change-Id: Icc0d9e8cb81f2b67bf99fdead423bfe8159714bc
Signed-off-by: Liu Xiaodong <xiaodong.liu@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16500
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

lib/ublk/ublk.c

@@ -113,6 +113,7 @@ struct spdk_ublk_dev {
 	int			retry_count;
 	uint32_t		queues_closed;
 	volatile bool		is_closing;
+	ublk_start_cb		start_cb;
 	ublk_del_cb		del_cb;
 	void			*cb_arg;
 	uint32_t		ctrl_cmd_op;
@@ -1197,6 +1198,9 @@ ublk_set_params(struct spdk_ublk_dev *ublk)
 	if (rc < 0) {
 		SPDK_ERRLOG("UBLK can't set params for dev %d, rc %s\n", ublk->ublk_id, spdk_strerror(-rc));
 		ublk_delete_dev(ublk);
+		if (ublk->start_cb) {
+			ublk->start_cb(ublk->cb_arg, rc);
+		}
 	}
 }
 
@@ -1341,7 +1345,8 @@ ublk_queue_run(void *arg1)
 
 int
 ublk_start_disk(const char *bdev_name, uint32_t ublk_id,
-		uint32_t num_queues, uint32_t queue_depth)
+		uint32_t num_queues, uint32_t queue_depth,
+		ublk_start_cb start_cb, void *cb_arg)
 {
 	int			rc;
 	uint32_t		i;
@@ -1362,6 +1367,8 @@ ublk_start_disk(const char *bdev_name, uint32_t ublk_id,
 	if (ublk == NULL) {
 		return -ENOMEM;
 	}
+	ublk->start_cb = start_cb;
+	ublk->cb_arg = cb_arg;
 	ublk->cdev_fd = -1;
 	ublk->ublk_id = ublk_id;
 	UBLK_DEBUGLOG(ublk, "bdev %s num_queues %d queue_depth %d\n",
@@ -1462,10 +1469,14 @@ ublk_finish_start(struct spdk_ublk_dev *ublk)
 		}
 	}
 
-	return;
+	goto out;
 
 err:
 	ublk_delete_dev(ublk);
+out:
+	if (ublk->start_cb) {
+		ublk->start_cb(ublk->cb_arg, rc);
+	}
 }
 
 SPDK_LOG_REGISTER_COMPONENT(ublk)

lib/ublk/ublk_internal.h

@@ -17,12 +17,14 @@
 extern "C" {
 #endif
 
+typedef void (*ublk_start_cb)(void *cb_arg, int result);
 typedef void (*ublk_del_cb)(void *cb_arg);
 
 int ublk_create_target(const char *cpumask_str);
 int ublk_destroy_target(spdk_ublk_fini_cb cb_fn, void *cb_arg);
 int ublk_start_disk(const char *bdev_name, uint32_t ublk_id,
-		    uint32_t num_queues, uint32_t queue_depth);
+		    uint32_t num_queues, uint32_t queue_depth,
+		    ublk_start_cb start_cb, void *cb_arg);
 int ublk_stop_disk(uint32_t ublk_id, ublk_del_cb del_cb, void *cb_arg);
 struct spdk_ublk_dev *ublk_dev_find_by_id(uint32_t ublk_id);
 uint32_t ublk_dev_get_id(struct spdk_ublk_dev *ublk);

lib/ublk/ublk_rpc.c

@@ -81,6 +81,7 @@ struct rpc_ublk_start_disk {
 	uint32_t	ublk_id;
 	uint32_t	num_queues;
 	uint32_t	queue_depth;
+	struct spdk_jsonrpc_request *request;
 };
 
 static const struct spdk_json_object_decoder rpc_ublk_start_disk_decoders[] = {
@@ -90,39 +91,66 @@ static const struct spdk_json_object_decoder rpc_ublk_start_disk_decoders[] = {
 	{"queue_depth", offsetof(struct rpc_ublk_start_disk, queue_depth), spdk_json_decode_uint32, true},
 };
 
+static void
+free_rpc_ublk_start_disk(struct rpc_ublk_start_disk *req)
+{
+	free(req->bdev_name);
+	free(req);
+}
+
+static void
+rpc_ublk_start_disk_done(void *cb_arg, int rc)
+{
+	struct rpc_ublk_start_disk *req = cb_arg;
+	struct spdk_json_write_ctx *w;
+
+	if (rc == 0) {
+		w = spdk_jsonrpc_begin_result(req->request);
+		spdk_json_write_uint32(w, req->ublk_id);
+		spdk_jsonrpc_end_result(req->request, w);
+	} else {
+		spdk_jsonrpc_send_error_response(req->request, rc, spdk_strerror(-rc));
+	}
+
+	free_rpc_ublk_start_disk(req);
+}
+
 static void
 rpc_ublk_start_disk(struct spdk_jsonrpc_request *request,
 		    const struct spdk_json_val *params)
 {
-	struct spdk_json_write_ctx *w;
+	struct rpc_ublk_start_disk *req;
-	struct rpc_ublk_start_disk req = {};
 	int rc;
 
-	req.queue_depth = UBLK_DEV_QUEUE_DEPTH;
+	req = calloc(1, sizeof(*req));
-	req.num_queues = UBLK_DEV_NUM_QUEUE;
+	if (req == NULL) {
+		SPDK_ERRLOG("could not allocate request.\n");
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INTERNAL_ERROR, "Out of memory");
+		return;
+	}
+	req->request = request;
+	req->queue_depth = UBLK_DEV_QUEUE_DEPTH;
+	req->num_queues = UBLK_DEV_NUM_QUEUE;
 
 	if (spdk_json_decode_object(params, rpc_ublk_start_disk_decoders,
 				    SPDK_COUNTOF(rpc_ublk_start_disk_decoders),
-				    &req)) {
+				    req)) {
 		SPDK_ERRLOG("spdk_json_decode_object failed\n");
 		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INTERNAL_ERROR,
 						 "spdk_json_decode_object failed");
 		goto out;
 	}
 
-	rc = ublk_start_disk(req.bdev_name, req.ublk_id, req.num_queues, req.queue_depth);
+	rc = ublk_start_disk(req->bdev_name, req->ublk_id, req->num_queues, req->queue_depth,
+			     rpc_ublk_start_disk_done, req);
 	if (rc != 0) {
-		spdk_jsonrpc_send_error_response(request, rc, spdk_strerror(-rc));
+		rpc_ublk_start_disk_done(req, rc);
-		goto out;
 	}
 
-	w = spdk_jsonrpc_begin_result(request);
+	return;
-	spdk_json_write_uint32(w, req.ublk_id);
-	spdk_jsonrpc_end_result(request, w);
-	goto out;
 
 out:
-	free(req.bdev_name);
+	free_rpc_ublk_start_disk(req);
 }
 
 SPDK_RPC_REGISTER("ublk_start_disk", rpc_ublk_start_disk, SPDK_RPC_RUNTIME)