Use supervisor mount namespace for mount (#20144)

Author: Furisto

components/ws-daemon/pkg/iws/iws.go

@@ -709,15 +709,15 @@ func (wbs *InWorkspaceServiceServer) MountSysfs(ctx context.Context, req *api.Mo
 
 func (wbs *InWorkspaceServiceServer) MountNfs(ctx context.Context, req *api.MountNfsRequest) (resp *api.MountNfsResponse, err error) {
 	var (
-		reqPID = req.Pid
-		nfsPID uint64
+		reqPID        = req.Pid
+		supervisorPID uint64
 	)
 	defer func() {
 		if err == nil {
 			return
 		}
 
-		log.WithError(err).WithFields(wbs.Session.OWI()).WithField("procPID", nfsPID).WithField("reqPID", reqPID).WithFields(wbs.Session.OWI()).Error("cannot mount nfs")
+		log.WithError(err).WithFields(wbs.Session.OWI()).WithField("procPID", supervisorPID).WithField("reqPID", reqPID).WithFields(wbs.Session.OWI()).Error("cannot mount nfs")
 		if _, ok := status.FromError(err); !ok {
 			err = status.Error(codes.Internal, "cannot mount nfs")
 		}
@@ -737,9 +737,9 @@ func (wbs *InWorkspaceServiceServer) MountNfs(ctx context.Context, req *api.Moun
 		return nil, xerrors.Errorf("cannot find container PID for containerID %v: %w", wscontainerID, err)
 	}
 
-	nfsPID, err = wbs.Uidmapper.findHostPID(containerPID, uint64(req.Pid))
+	supervisorPID, err = wbs.Uidmapper.findSupervisorPID(containerPID)
 	if err != nil {
-		return nil, xerrors.Errorf("cannot map in-container PID %d (container PID: %d): %w", req.Pid, containerPID, err)
+		return nil, xerrors.Errorf("cannot map supervisor PID %d (container PID: %d): %w", req.Pid, containerPID, err)
 	}
 
 	nodeStaging, err := os.MkdirTemp("", "nfs-staging")
@@ -774,7 +774,7 @@ func (wbs *InWorkspaceServiceServer) MountNfs(ctx context.Context, req *api.Moun
 		}
 	}
 
-	err = moveMount(wbs.Session.InstanceID, int(nfsPID), nodeStaging, req.Target)
+	err = moveMount(wbs.Session.InstanceID, int(supervisorPID), nodeStaging, req.Target)
 	if err != nil {
 		return nil, err
 	}

components/ws-daemon/pkg/iws/uidmap.go

@@ -174,7 +174,6 @@ func (m *Uidmapper) findHostPID(containerPID, inContainerPID uint64) (uint64, er
 		seen[p] = struct{}{}
 
 		p = filepath.Join(m.Config.ProcLocation, p)
-
 		pid, nspid, err := readStatusFile(filepath.Join(p, "status"))
 		if err != nil {
 			log.WithField("file", filepath.Join(p, "status")).WithError(err).Error("findHostPID: cannot read PID file")
@@ -201,6 +200,54 @@ func (m *Uidmapper) findHostPID(containerPID, inContainerPID uint64) (uint64, er
 	}
 }
 
+func (m *Uidmapper) findSupervisorPID(containerPID uint64) (uint64, error) {
+	paths := []string{fmt.Sprint(containerPID)}
+	seen := make(map[string]struct{})
+
+	for {
+		if len(paths) == 0 {
+			return 0, xerrors.Errorf("cannot find supervisor PID for container %v", containerPID)
+		}
+
+		p := paths[0]
+		paths = paths[1:]
+
+		if _, ok := seen[p]; ok {
+			continue
+		}
+		seen[p] = struct{}{}
+
+		procPath := filepath.Join(m.Config.ProcLocation, p)
+		cmdline, err := os.ReadFile(filepath.Join(procPath, "cmdline"))
+		if err != nil {
+			log.WithField("file", filepath.Join(procPath, "cmdline")).WithError(err).Error("cannot read cmdline")
+			continue
+		}
+
+		if strings.HasPrefix(string(cmdline), "supervisor") {
+			pid, err := strconv.ParseUint(p, 10, 64)
+			if err != nil {
+				return 0, err
+			}
+
+			return pid, nil
+		}
+
+		taskfn := filepath.Join(procPath, "task")
+		tasks, err := os.ReadDir(taskfn)
+		if err != nil {
+			continue
+		}
+		for _, task := range tasks {
+			cldrn, err := os.ReadFile(filepath.Join(taskfn, task.Name(), "children"))
+			if err != nil {
+				continue
+			}
+			paths = append(paths, strings.Fields(string(cldrn))...)
+		}
+	}
+}
+
 func readStatusFile(fn string) (pid uint64, nspid []uint64, err error) {
 	f, err := os.Open(fn)
 	if err != nil {