bdev_null: add null bdev resize rpc

Usually null bdev is used in testing.
The resize function provides flexibility

Change-Id: I603db0b85ff13a86d38ccc8dd6f260807393df93
Signed-off-by: Jin Yu <jin.yu@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/5797
Community-CI: Broadcom CI
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

doc/jsonrpc.md

@@ -2268,6 +2268,43 @@ Example response:
 }
 ~~~
 
+## bdev_null_resize {#rpc_bdev_null_resize}
+
+Resize @ref bdev_config_null.
+
+### Parameters
+
+Name                    | Optional | Type        | Description
+----------------------- | -------- | ----------- | -----------
+name                    | Required | string      | Bdev name
+new_size                | Required | number      | Bdev new capacity in MB
+
+### Example
+
+Example request:
+
+~~~
+{
+  "params": {
+    "name": "Null0",
+    "new_size": 4096
+  },
+  "jsonrpc": "2.0",
+  "method": "bdev_null_resize",
+  "id": 1
+}
+~~~
+
+Example response:
+
+~~~
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": true
+}
+~~~
+
 ## bdev_aio_create {#rpc_bdev_aio_create}
 
 Construct @ref bdev_config_aio.

module/bdev/null/bdev_null.c

@@ -420,6 +420,34 @@ bdev_null_initialize(void)
 	return 0;
 }
 
+int
+bdev_null_resize(struct spdk_bdev *bdev, const uint64_t new_size_in_mb)
+{
+	uint64_t current_size_in_mb;
+	uint64_t new_size_in_byte;
+	int rc;
+
+	if (bdev->module != &null_if) {
+		return -EINVAL;
+	}
+
+	current_size_in_mb = bdev->blocklen * bdev->blockcnt / (1024 * 1024);
+	if (new_size_in_mb < current_size_in_mb) {
+		SPDK_ERRLOG("The new bdev size must not be smaller than current bdev size.\n");
+		return -EINVAL;
+	}
+
+	new_size_in_byte = new_size_in_mb * 1024 * 1024;
+
+	rc = spdk_bdev_notify_blockcnt_change(bdev, new_size_in_byte / bdev->blocklen);
+	if (rc != 0) {
+		SPDK_ERRLOG("failed to notify block cnt change.\n");
+		return rc;
+	}
+
+	return 0;
+}
+
 static void
 _bdev_null_finish_cb(void *arg)
 {

module/bdev/null/bdev_null.h

@@ -63,5 +63,12 @@ int bdev_null_create(struct spdk_bdev **bdev, const struct spdk_null_bdev_opts *
  */
 void bdev_null_delete(struct spdk_bdev *bdev, spdk_delete_null_complete cb_fn,
 		      void *cb_arg);
+/**
+ * Resize null bdev.
+ *
+ * \param bdev Pointer to null bdev.
+ * \param new_size_in_mb The new size in MiB for this bdev
+ */
+int bdev_null_resize(struct spdk_bdev *bdev, const uint64_t new_size_in_mb);
 
 #endif /* SPDK_BDEV_NULL_H */

module/bdev/null/bdev_null_rpc.c

@@ -206,3 +206,53 @@ cleanup:
 }
 SPDK_RPC_REGISTER("bdev_null_delete", rpc_bdev_null_delete, SPDK_RPC_RUNTIME)
 SPDK_RPC_REGISTER_ALIAS_DEPRECATED(bdev_null_delete, delete_null_bdev)
+
+struct rpc_bdev_null_resize {
+	char *name;
+	uint64_t new_size;
+};
+
+static const struct spdk_json_object_decoder rpc_bdev_null_resize_decoders[] = {
+	{"name", offsetof(struct rpc_bdev_null_resize, name), spdk_json_decode_string},
+	{"new_size", offsetof(struct rpc_bdev_null_resize, new_size), spdk_json_decode_uint64}
+};
+
+static void
+free_rpc_bdev_null_resize(struct rpc_bdev_null_resize *req)
+{
+	free(req->name);
+}
+
+static void
+spdk_rpc_bdev_null_resize(struct spdk_jsonrpc_request *request,
+			  const struct spdk_json_val *params)
+{
+	struct rpc_bdev_null_resize req = {};
+	struct spdk_bdev *bdev;
+	int rc;
+
+	if (spdk_json_decode_object(params, rpc_bdev_null_resize_decoders,
+				    SPDK_COUNTOF(rpc_bdev_null_resize_decoders),
+				    &req)) {
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INTERNAL_ERROR,
+						 "spdk_json_decode_object failed");
+		goto cleanup;
+	}
+
+	bdev = spdk_bdev_get_by_name(req.name);
+	if (bdev == NULL) {
+		spdk_jsonrpc_send_error_response(request, -ENODEV, spdk_strerror(ENODEV));
+		goto cleanup;
+	}
+
+	rc = bdev_null_resize(bdev, req.new_size);
+	if (rc) {
+		spdk_jsonrpc_send_error_response(request, rc, spdk_strerror(-rc));
+		goto cleanup;
+	}
+
+	spdk_jsonrpc_send_bool_response(request, true);
+cleanup:
+	free_rpc_bdev_null_resize(&req);
+}
+SPDK_RPC_REGISTER("bdev_null_resize", spdk_rpc_bdev_null_resize, SPDK_RPC_RUNTIME)

scripts/rpc.py

@@ -382,6 +382,17 @@ if __name__ == "__main__":
     p.add_argument('name', help='null bdev name')
     p.set_defaults(func=bdev_null_delete)
 
+    def bdev_null_resize(args):
+        print_json(rpc.bdev.bdev_null_resize(args.client,
+                                             name=args.name,
+                                             new_size=int(args.new_size)))
+
+    p = subparsers.add_parser('bdev_null_resize',
+                              help='Resize a null bdev')
+    p.add_argument('name', help='null bdev name')
+    p.add_argument('new_size', help='new bdev size for resize operation. The unit is MiB')
+    p.set_defaults(func=bdev_null_resize)
+
     def bdev_aio_create(args):
         print_json(rpc.bdev.bdev_aio_create(args.client,
                                             filename=args.filename,

scripts/rpc/bdev.py

@@ -277,6 +277,20 @@ def bdev_null_delete(client, name):
     return client.call('bdev_null_delete', params)
 
 
+def bdev_null_resize(client, name, new_size):
+    """Resize null bdev in the system.
+
+    Args:
+        name: name of null bdev to resize
+        new_size: new bdev size of resize operation. The unit is MiB
+    """
+    params = {
+            'name': name,
+            'new_size': new_size,
+            }
+    return client.call('bdev_null_resize', params)
+
+
 @deprecated_alias('get_raid_bdevs')
 def bdev_raid_get_bdevs(client, category):
     """Get list of raid bdevs based on category