fix cntrfs example

examples/cntrfs.rs

@@ -51,15 +51,18 @@ fn main() {
     }
     #[cfg(feature = "profiling")] PROFILER.lock().unwrap().start("./cntrfs.profile").unwrap();
 
-    let cntr = CntrFs::new(&CntrMountOptions {
-        prefix: &args[1],
-        splice_read: cfg!(feature = "splice_read"),
-        splice_write: cfg!(feature = "splice_write"),
-        uid_map: cntr::DEFAULT_ID_MAP,
-        gid_map: cntr::DEFAULT_ID_MAP,
-        effective_uid: None,
-        effective_gid: None,
-    }).unwrap();
+    let cntr = CntrFs::new(
+        &CntrMountOptions {
+            prefix: &args[1],
+            splice_read: cfg!(feature = "splice_read"),
+            splice_write: cfg!(feature = "splice_write"),
+            uid_map: cntr::DEFAULT_ID_MAP,
+            gid_map: cntr::DEFAULT_ID_MAP,
+            effective_uid: None,
+            effective_gid: None,
+        },
+        None,
+    ).unwrap();
 
     cntr.mount(Path::new(&args[2]), &None).unwrap();
     let guard = MountGuard { mount_point: args[2].clone() };

src/attach/mod.rs

@@ -62,7 +62,6 @@ pub fn attach(opts: &AttachOptions) -> Result<Void> {
 
     let cntrfs = tryfmt!(
         fs::CntrFs::new(
-            dotcntr,
             &fs::CntrMountOptions {
                 prefix: "/",
                 splice_read: cfg!(feature = "splice_read"),
@@ -72,6 +71,7 @@ pub fn attach(opts: &AttachOptions) -> Result<Void> {
                 effective_uid,
                 effective_gid,
             },
+            Some(dotcntr),
         ),
         "cannot mount filesystem"
     );

src/fs.rs

@@ -77,7 +77,7 @@ struct InodeCounter {
 pub struct CntrFs {
     prefix: String,
     root_inode: Arc<Inode>,
-    dotcntr: Arc<DotcntrDir>,
+    dotcntr: Arc<Option<DotcntrDir>>,
     inode_mapping: Arc<Mutex<HashMap<InodeKey, u64>>>,
     inodes: Arc<ConcHashMap<u64, Arc<Inode>>>,
     inode_counter: Arc<RwLock<InodeCounter>>,
@@ -186,7 +186,7 @@ fn open_static_dnode(static_ino: u64, path: &Path) -> Result<Arc<Inode>> {
 
 
 impl CntrFs {
-    pub fn new(dotcntr: DotcntrDir, options: &CntrMountOptions) -> Result<CntrFs> {
+    pub fn new(options: &CntrMountOptions, dotcntr: Option<DotcntrDir>) -> Result<CntrFs> {
         let fuse_fd = tryfmt!(fusefd::open(), "failed to initialize fuse");
 
         let limit = resource::Rlimit {
@@ -542,25 +542,28 @@ impl CntrFs {
         Ok((attr, generation))
     }
 
+
     pub fn lookup_inode(&mut self, parent: u64, name: &OsStr) -> nix::Result<(FileAttr, u64)> {
         fsuid::set_root();
 
         if parent == fuse::FUSE_ROOT_ID && name == ".cntr" {
-            let d = Arc::clone(&self.dotcntr);
-            self.lookup_from_fd(LookupFile::Borrow(&d.file))
-        } else {
-            let parent_inode = try!(self.inode(&parent));
-            let parent_fd = parent_inode.fd.read();
-            let fd = try!(fcntl::openat(
-                parent_fd.raw(),
-                name,
-                OFlag::O_PATH | OFlag::O_NOFOLLOW | OFlag::O_CLOEXEC,
-                stat::Mode::empty(),
-            ));
-            let file = unsafe { File::from_raw_fd(fd) };
-
-            self.lookup_from_fd(LookupFile::Donate(file))
+            let dotcntr = Arc::clone(&self.dotcntr);
+            if let Some(ref dotcntr) = *dotcntr {
+                return self.lookup_from_fd(LookupFile::Borrow(&dotcntr.file));
+            }
         }
+
+        let parent_inode = try!(self.inode(&parent));
+        let parent_fd = parent_inode.fd.read();
+        let fd = try!(fcntl::openat(
+            parent_fd.raw(),
+            name,
+            OFlag::O_PATH | OFlag::O_NOFOLLOW | OFlag::O_CLOEXEC,
+            stat::Mode::empty(),
+        ));
+        let file = unsafe { File::from_raw_fd(fd) };
+
+        self.lookup_from_fd(LookupFile::Donate(file))
     }
 }