cfuse: daemonize by default

We have to fork, then start client, to avoid killing our pthreads.  Use
a socketpair to tell the parent process about mount success/failure.

src/cfuse.cc

@@ -46,6 +46,7 @@ int main(int argc, const char **argv, const char *envp[]) {
   env_to_vec(args);
 
   common_set_defaults(false);
+  g_conf.daemonize = true;
   common_init(args, "cfuse", true);
 
   // args for fuse
@@ -71,44 +72,86 @@ int main(int argc, const char **argv, const char *envp[]) {
 
   // start up network
   SimpleMessenger *messenger = new SimpleMessenger();
-  cout << "mounting ceph" << std::endl;
   messenger->register_entity(entity_name_t::CLIENT());
   Client *client = new Client(messenger, &mc);
 
-  messenger->start();
+  // we need to handle the forking ourselves.
+  bool daemonize = g_conf.daemonize;
+  g_conf.daemonize = false;
 
-  int r;
+  int fd[2] = {0, 0};  // parent's, child's
+  pid_t childpid = 0;
+  if (daemonize) {
+    int r = socketpair(AF_UNIX, SOCK_STREAM, 0, fd);
+    if (r < 0) {
+      cerr << "cfuse[" << getpid() << "]: unable to create socketpair: " << strerror(errno) << std::endl;
+      exit(1);
+    }
 
-  // start client
-  client->init();
+    childpid = fork();
+  }
+
+  if (childpid == 0) {
+    //cout << "child, mounting" << std::endl;
+    ::close(fd[0]);
+
+    cout << "cfuse[" << getpid() << "]: starting ceph client" << std::endl;
+
+    messenger->start();
+
+    // start client
+    client->init();
     
-  // start up fuse
-  // use my argc, argv (make sure you pass a mount point!)
-  r = client->mount();
-  if (r < 0)
-    goto out_shutdown;
+    // start up fuse
+    // use my argc, argv (make sure you pass a mount point!)
+    int r = client->mount();
+    if (r < 0) {
+      cerr << "cfuse[" << getpid() << "]: ceph mount failed with " << strerror(-r) << std::endl;
+      goto out_shutdown;
+    }
+    
+    dout_create_rank_symlink(client->get_nodeid().v);
+    cerr << "cfuse[" << getpid() << "]: starting fuse" << std::endl;
+    if (g_conf.fuse_ll)
+      r = ceph_fuse_ll_main(client, argc, argv, fd[1]);
+    else
+      r = ceph_fuse_main(client, argc, argv);
+    cerr << "cfuse[" << getpid() << "]: fuse finished with error " << r << std::endl;
+    
+    client->unmount();
+    //cout << "unmounted" << std::endl;
+    
+  out_shutdown:
+    client->shutdown();
+    delete client;
+    
+    // wait for messenger to finish
+    messenger->wait();
 
-  dout_create_rank_symlink(client->get_nodeid().v);
-  cout << "starting fuse" << std::endl;
+    if (daemonize) {
+      //cout << "child signalling parent with " << r << std::endl;
+      ::write(fd[1], &r, sizeof(r));
+    }
 
-  //cerr << "starting fuse on pid " << getpid() << std::endl;
-  if (g_conf.fuse_ll)
-    ceph_fuse_ll_main(client, argc, argv);
-  else
-    ceph_fuse_main(client, argc, argv);
-  //cerr << "fuse finished on pid " << getpid() << std::endl;
+    //cout << "child done" << std::endl;
+    return r;
+  } else {
+    // i am the parent
+    //cout << "parent, waiting for signal" << std::endl;
+    ::close(fd[1]);
 
-  cout << "fuse finished, unmounting ceph" << std::endl;
-  client->unmount();
-  cout << "unmounted" << std::endl;
-
- out_shutdown:
-  client->shutdown();
-  delete client;
-  
-  // wait for messenger to finish
-  messenger->wait();
-  
-  return r;
+    int r = -1;
+    ::read(fd[0], &r, sizeof(r));
+    if (r == 0) {
+      // close stdout, etc.
+      //cout << "success" << std::endl;
+      ::close(0);
+      ::close(1);
+      ::close(2);
+    } else {
+      cerr << "cfuse[" << getpid() << "]: mount failed: " << strerror(-r) << std::endl;
+    }
+    return r;
+  }
 }
 

src/client/fuse_ll.cc

@@ -422,8 +422,25 @@ static void ceph_ll_statfs(fuse_req_t req, fuse_ino_t ino)
     fuse_reply_err(req, -r);
 }
 
+int fd_on_success = 0;
+
+static void do_init(void *foo, fuse_conn_info *bar)
+{
+  if (fd_on_success) {
+    //cout << "fuse init signaling on fd " << fd_on_success << std::endl;
+    int r = 0;
+    ::write(fd_on_success, &r, sizeof(r));
+    //cout << "fuse init done signaling on fd " << fd_on_success << std::endl;
+
+    // close stdout, etc.
+    ::close(0);
+    ::close(1);
+    ::close(2);
+  }
+}
+
 static struct fuse_lowlevel_ops ceph_ll_oper = {
- init: 0,
+ init: do_init,
  destroy: 0,
  lookup: ceph_ll_lookup,
  forget: ceph_ll_forget,
@@ -459,9 +476,11 @@ static struct fuse_lowlevel_ops ceph_ll_oper = {
  bmap: 0
 };
 
-int ceph_fuse_ll_main(Client *c, int argc, const char *argv[])
+int ceph_fuse_ll_main(Client *c, int argc, const char *argv[], int fd)
 {
-  cout << "ceph_fuse_ll_main starting fuse on pid " << getpid() << std::endl;
+  //cout << "ceph_fuse_ll_main starting fuse on pid " << getpid() << std::endl;
+
+  fd_on_success = fd;
 
   client = c;
 
@@ -507,10 +526,13 @@ int ceph_fuse_ll_main(Client *c, int argc, const char *argv[])
       fuse_session_destroy(se);
     }
     fuse_unmount(mountpoint, ch);
+    err = 0;
+  } else {
+    err = -errno;
   }
   fuse_opt_free_args(&args);
   
-  cout << "ceph_fuse_ll_main done, err=" << err << std::endl;
-  return err ? 1 : 0;
+  //cout << "ceph_fuse_ll_main done, err=" << err << std::endl;
+  return err;
 }
 

src/client/fuse_ll.h

@@ -12,4 +12,4 @@
  * 
  */
 
-int ceph_fuse_ll_main(Client *c, int argc, const char *argv[]);
+int ceph_fuse_ll_main(Client *c, int argc, const char *argv[], int fd_on_success);