Add support for creating subfolders in cgroupv2

src/fs/cgroup.rs

@@ -82,7 +82,29 @@ impl Cgroup {
     /// Create this control group.
     pub fn create(&self) -> Result<()> {
         if self.hier.v2() {
-            create_v2_cgroup(self.hier.root(), &self.path, &self.specified_controllers)
+            create_v2_cgroup(
+                self.hier.root(),
+                &self.path,
+                &self.specified_controllers,
+                true,
+            )
+        } else {
+            for subsystem in &self.subsystems {
+                subsystem.to_controller().create();
+            }
+            Ok(())
+        }
+    }
+
+    /// Create this control group, don't enable subtree
+    pub fn create_disabled(&self) -> Result<()> {
+        if self.hier.v2() {
+            create_v2_cgroup(
+                self.hier.root(),
+                &self.path,
+                &self.specified_controllers,
+                false,
+            )
         } else {
             for subsystem in &self.subsystems {
                 subsystem.to_controller().create();
@@ -127,7 +149,7 @@ impl Cgroup {
         path: P,
         relative_paths: HashMap<String, String>,
     ) -> Result<Cgroup> {
-        let cg = Cgroup::load_with_relative_paths(hier, path, relative_paths);
+        let cg = Cgroup::load_with_relative_paths(hier, path, &relative_paths);
         cg.create()?;
         Ok(cg)
     }
@@ -185,38 +207,43 @@ impl Cgroup {
     ///
     /// Returns a handle to the control group (that possibly does not exist until `create()` has
     /// been called on the cgroup.
-    ///
-    /// Note that this method is only meaningful for cgroup v1, call it is equivalent to call `load` in the v2 mode
     pub fn load_with_relative_paths<P: AsRef<Path>>(
         hier: Box<dyn Hierarchy>,
         path: P,
-        relative_paths: HashMap<String, String>,
+        relative_paths: &HashMap<String, String>,
     ) -> Cgroup {
-        // relative_paths only valid for cgroup v1
-        if hier.v2() {
-            return Self::load(hier, path);
-        }
-
         let path = path.as_ref();
         let mut subsystems = hier.subsystems();
-        if path.as_os_str() != "" {
-            subsystems = subsystems
-                .into_iter()
-                .map(|x| {
-                    let cn = x.controller_name();
-                    if relative_paths.contains_key(&cn) {
-                        let rp = relative_paths.get(&cn).unwrap();
-                        let valid_path = rp.trim_start_matches('/').to_string();
-                        let mut p = PathBuf::from(valid_path);
+        subsystems = subsystems
+            .into_iter()
+            .map(|x| {
+                let cn = if hier.v2() {
+                    "".to_string()
+                } else {
+                    x.controller_name()
+                };
+                if relative_paths.contains_key(&cn) {
+                    let rp = relative_paths.get(&cn).unwrap();
+                    let valid_path = rp.trim_start_matches('/').to_string();
+                    let mut p = PathBuf::from(valid_path);
+                    if path.as_os_str() != "" {
                         p.push(path);
-                        x.enter(p.as_ref())
-                    } else {
-                        x.enter(path)
                     }
-                })
-                .collect::<Vec<_>>();
-        }
+                    x.enter(p.as_ref())
+                } else if path.as_os_str() != "" {
+                    x.enter(path)
+                } else {
+                    x
+                }
+            })
+            .collect::<Vec<_>>();
+
+        let rp = relative_paths.get("").unwrap();
+        let valid_path = rp.trim_start_matches('/').to_string();
+        let mut pb = PathBuf::from(valid_path);
+        pb.push(path);
 
+        let path = if hier.v2() { pb.as_path() } else { path };
         Cgroup {
             subsystems,
             hier,
@@ -530,6 +557,7 @@ fn create_v2_cgroup(
     root: PathBuf,
     path: &str,
     specified_controllers: &Option<Vec<String>>,
+    enabled: bool,
 ) -> Result<()> {
     // controler list ["memory", "cpu"]
     let controllers = if let Some(s_controllers) = specified_controllers.clone() {
@@ -545,7 +573,9 @@ fn create_v2_cgroup(
     let mut fp = root;
 
     // enable for root
-    enable_controllers(&controllers, &fp);
+    if enabled {
+        enable_controllers(&controllers, &fp);
+    }
 
     // path: "a/b/c"
     let elements = path.split('/').collect::<Vec<&str>>();
@@ -560,7 +590,7 @@ fn create_v2_cgroup(
             }
         }
 
-        if i < last_index {
+        if enabled && i < last_index {
             // enable controllers for substree
             enable_controllers(&controllers, &fp);
         }