rpc/blobfs: add cache size setting rpc

This RPC method can be used to set cache size of
blobfs, in case a smaller or larger memory scale
is requred by cache pool.

Change-Id: I8046c7caeaa15c67825f86d14ae0b79395d51daf
Signed-off-by: Xiaodong Liu <xiaodong.liu@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/471870
Community-CI: Broadcom SPDK FC-NVMe CI <spdk-ci.pdl@broadcom.com>
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>

CHANGELOG.md

@@ -16,6 +16,8 @@ sent.
 
 Added boolean return value for function spdk_fs_set_cache_size to indicate its operation result.
 
+Added `blobfs_set_cache_size` RPC method to set cache size for blobstore filesystem.
+
 ## v19.10:
 
 ### rpc

doc/jsonrpc.md

@@ -6174,6 +6174,47 @@ Example response:
   "id": 1,
   "result": "true"
 }
+~~
+
+## blobfs_set_cache_size {#rpc_blobfs_set_cache_size}
+
+Set cache pool size for blobfs filesystems.  This RPC is only permitted when the cache pool is not already initialized.
+
+The cache pool is initialized when the first blobfs filesystem is initialized or loaded.  It is freed when the all initialized or loaded filesystems are unloaded.
+
+### Parameters
+
+Name                    | Optional | Type        | Description
+----------------------- | -------- | ----------- | -----------
+size_in_mb              | Required | number      | Cache size in megabytes
+
+### Response
+
+True if cache size is set successfully; False if failed to set.
+
+### Example
+
+Example request:
+
+~~~
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "method": "blobfs_set_cache_size",
+  "params": {
+    "size_in_mb": 512,
+  }
+}
+~~~
+
+Example response:
+
+~~~
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": true
+}
 ~~~
 
 # Miscellaneous RPC commands

module/blobfs/bdev/blobfs_bdev_rpc.c

@@ -50,6 +50,49 @@
 
 #define MIN_CLUSTER_SZ (1024 * 1024)
 
+struct rpc_blobfs_set_cache_size {
+	uint64_t size_in_mb;
+};
+
+static const struct spdk_json_object_decoder rpc_blobfs_set_cache_size_decoders[] = {
+	{"size_in_mb", offsetof(struct rpc_blobfs_set_cache_size, size_in_mb), spdk_json_decode_uint64},
+};
+
+static void
+spdk_rpc_blobfs_set_cache_size(struct spdk_jsonrpc_request *request,
+			       const struct spdk_json_val *params)
+{
+	struct rpc_blobfs_set_cache_size req;
+	struct spdk_json_write_ctx *w;
+	int rc;
+
+	if (spdk_json_decode_object(params, rpc_blobfs_set_cache_size_decoders,
+				    SPDK_COUNTOF(rpc_blobfs_set_cache_size_decoders),
+				    &req)) {
+		SPDK_ERRLOG("spdk_json_decode_object failed\n");
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS,
+						 "spdk_json_decode_object failed");
+
+		return;
+	}
+
+	if (req.size_in_mb == 0) {
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS,
+						 "spdk_json_decode_object failed");
+
+		return;
+	}
+
+	rc = spdk_fs_set_cache_size(req.size_in_mb);
+
+	w = spdk_jsonrpc_begin_result(request);
+	spdk_json_write_bool(w, rc == 0);
+	spdk_jsonrpc_end_result(request, w);
+}
+
+SPDK_RPC_REGISTER("blobfs_set_cache_size", spdk_rpc_blobfs_set_cache_size,
+		  SPDK_RPC_STARTUP | SPDK_RPC_RUNTIME)
+
 struct rpc_blobfs_detect {
 	char *bdev_name;
 

scripts/rpc.py

@@ -2225,6 +2225,14 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
     p.add_argument('mountpoint', help='Mountpoint path in host to mount blobfs. Example: /mnt/.')
     p.set_defaults(func=blobfs_mount)
 
+    def blobfs_set_cache_size(args):
+        print(rpc.blobfs.blobfs_set_cache_size(args.client,
+                                               size_in_mb=args.size_in_mb))
+
+    p = subparsers.add_parser('blobfs_set_cache_size', help='Set cache size for blobfs')
+    p.add_argument('size_in_mb', help='Cache size for blobfs in megabytes.', type=int)
+    p.set_defaults(func=blobfs_set_cache_size)
+
     def check_called_name(name):
         if name in deprecated_aliases:
             print("{} is deprecated, use {} instead.".format(name, deprecated_aliases[name]), file=sys.stderr)

scripts/rpc/blobfs.py

@@ -40,3 +40,18 @@ def blobfs_mount(client, bdev_name, mountpoint):
         'mountpoint': mountpoint
     }
     return client.call('blobfs_mount', params)
+
+
+def blobfs_set_cache_size(client, size_in_mb):
+    """Set cache size for the blobstore filesystem.
+
+    Args:
+        size_in_mb: Cache size in megabytes
+
+    Returns:
+        True if cache size is set successfully; False if failed to set.
+    """
+    params = {
+        'size_in_mb': size_in_mb
+    }
+    return client.call('blobfs_set_cache_size', params)