rbd nbd: Add cond to signal nbd disconnection

With the ioctl interface we know when a disconnect has been executed
because the NBD_DO_IO ioctl will return. The netlink interface returns
after the nl connect cmd call has completed, so this patch adds a cond
that signals when a nl disconnect/NBD_DISCONNECT has been executed and
the server thread has handled the resulting NBD_CMD_DISC.

Signed-off-by: Mike Christie <mchristi@redhat.com>

diff --git a/src/tools/rbd_nbd/rbd-nbd.cc b/src/tools/rbd_nbd/rbd-nbd.cc
index d0abdff5a8140452794d77903b9513ec8cc1fcc9..9919a0dfdacd078a9ee0a0855b06bc1cc97446d7 100644 (file)
--- a/src/tools/rbd_nbd/rbd-nbd.cc
+++ b/src/tools/rbd_nbd/rbd-nbd.cc
@@ -141,6 +141,7 @@ public:
   NBDServer(int _fd, librbd::Image& _image)
     : fd(_fd)
     , image(_image)
+    , disconnect_lock("NBDServer::DisconnectLocker")
     , lock("NBDServer::Locker")
     , reader_thread(*this, &NBDServer::reader_entry)
     , writer_thread(*this, &NBDServer::writer_entry)
@@ -148,6 +149,8 @@ public:
   {}
 
 private:
+  Mutex disconnect_lock;
+  Cond disconnect_cond;
   std::atomic<bool> terminated = { false };
 
   void shutdown()
@@ -272,12 +275,12 @@ private:
       if (r < 0) {
        derr << "failed to read nbd request header: " << cpp_strerror(r)
             << dendl;
-       return;
+       goto signal;
       }
 
       if (ctx->request.magic != htonl(NBD_REQUEST_MAGIC)) {
        derr << "invalid nbd request header" << dendl;
-       return;
+       goto signal;
       }
 
       ctx->request.from = ntohll(ctx->request.from);
@@ -296,14 +299,14 @@ private:
         case NBD_CMD_DISC:
           // NBD_DO_IT will return when pipe is closed
          dout(0) << "disconnect request received" << dendl;
-          return;
+          goto signal;
         case NBD_CMD_WRITE:
           bufferptr ptr(ctx->request.len);
          r = safe_read_exact(fd, ptr.c_str(), ctx->request.len);
           if (r < 0) {
            derr << *ctx << ": failed to read nbd request data: "
                 << cpp_strerror(r) << dendl;
-            return;
+            goto signal;
          }
           ctx->data.push_back(ptr);
           break;
@@ -329,10 +332,14 @@ private:
         default:
          derr << *pctx << ": invalid request command" << dendl;
           c->release();
-          return;
+          goto signal;
       }
     }
     dout(20) << __func__ << ": terminated" << dendl;
+
+signal:
+    Mutex::Locker l(disconnect_lock);
+    disconnect_cond.Signal();
   }
 
   void writer_entry()
@@ -401,6 +408,15 @@ public:
     }
   }
 
+  void wait_for_disconnect()
+  {
+    if (!started)
+      return;
+
+    Mutex::Locker l(disconnect_lock);
+    disconnect_cond.Wait(disconnect_lock);
+  }
+
   ~NBDServer()
   {
     if (started) {