rbd-wnbd: adjust admin socket hook to accept image path

For each rbd-wnbd mapping we set an admin socket hook that can
be used to retrieve IO stats.

Now that the same daemon is reused for multiple mappings, we need
to distinguish the images when receiving a "stats" request.

For this reason, we'll add the image identifier to "wnbd stats"
admin socket commands.

Signed-off-by: Lucian Petrut <[email protected]>

Author: petrutlucian94

src/tools/rbd_wnbd/rbd_wnbd.cc

@@ -1159,8 +1159,8 @@ static int do_stats(std::string search_devpath)
 
     AdminSocketClient client = AdminSocketClient(cfg.admin_sock_path);
     std::string output;
-    std::string result = client.do_request("{\"prefix\":\"wnbd stats\"}",
-                                           &output);
+    std::string cmd = "{\"prefix\":\"wnbd stats " + cfg.devpath + "\"}";
+    std::string result = client.do_request(cmd, &output);
     if (!result.empty()) {
       std::cerr << "Admin socket error: " << result << std::endl;
       return -EINVAL;

src/tools/rbd_wnbd/wnbd_handler.cc

@@ -65,14 +65,21 @@ int WnbdHandler::wait()
   return err;
 }
 
+WnbdAdminHook::WnbdAdminHook(WnbdHandler *handler) : m_handler(handler)
+{
+  g_ceph_context->get_admin_socket()->register_command(
+    std::string("wnbd stats ") + m_handler->instance_name,
+    this, "get WNBD stats");
+}
+
 int WnbdAdminHook::call (
   std::string_view command, const cmdmap_t& cmdmap,
   const bufferlist&,
   Formatter *f,
   std::ostream& errss,
   bufferlist& out)
 {
-  if (command == "wnbd stats") {
+  if (command == "wnbd stats " + m_handler->instance_name) {
     return m_handler->dump_stats(f);
   }
   return -ENOSYS;

src/tools/rbd_wnbd/wnbd_handler.h

@@ -44,11 +44,7 @@ class WnbdAdminHook : public AdminSocketHook {
   WnbdHandler *m_handler;
 
 public:
-  explicit WnbdAdminHook(WnbdHandler *handler) :
-        m_handler(handler) {
-    g_ceph_context->get_admin_socket()->register_command(
-      "wnbd stats", this, "get WNBD stats");
-  }
+  explicit WnbdAdminHook(WnbdHandler *handler);
   ~WnbdAdminHook() override {
     g_ceph_context->get_admin_socket()->unregister_commands(this);
   }
@@ -140,6 +136,7 @@ class WnbdHandler
     void set_sense(uint8_t sense_key, uint8_t asc);
   };
 
+  friend WnbdAdminHook;
   friend std::ostream &operator<<(std::ostream &os, const IOContext &ctx);
 
   void send_io_response(IOContext *ctx);