Remove kernel.mounts.

We can get the mount namespace from the CreateProcessArgs in all cases where we
need it. This also gets rid of kernel.Destroy method, since the only thing it
was doing was DecRefing the mounts.

Removing the need to call kernel.SetRootMountNamespace also allowed for some
more simplifications in the container fs setup code.

PiperOrigin-RevId: 261357060

1 files changed, 10 insertions, 15 deletions

diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go
index 50cac0433..77e1aa456 100644
--- a/runsc/boot/loader.go
+++ b/runsc/boot/loader.go
@@ -527,12 +527,15 @@ func (l *Loader) run() error {
 		// cid for root container can be empty. Only subcontainers need it to set
 		// the mount location.
 		mntr := newContainerMounter(l.spec, "", l.goferFDs, l.k, l.mountHints)
-		if err := mntr.setupFS(ctx, l.conf, &l.rootProcArgs, l.rootProcArgs.Credentials); err != nil {
+
+		// Setup the root container.
+		if err := mntr.setupRootContainer(ctx, ctx, l.conf, func(mns *fs.MountNamespace) {
+			l.rootProcArgs.MountNamespace = mns
+		}); err != nil {
 			return err
 		}
 
-		rootCtx := l.rootProcArgs.NewContext(l.k)
-		if err := setExecutablePath(rootCtx, &l.rootProcArgs); err != nil {
+		if err := setExecutablePath(ctx, &l.rootProcArgs); err != nil {
 			return err
 		}
 
@@ -546,7 +549,7 @@ func (l *Loader) run() error {
 			}
 		}
 		if !hasHomeEnvv {
-			homeDir, err := getExecUserHome(rootCtx, l.rootProcArgs.MountNamespace, uint32(l.rootProcArgs.Credentials.RealKUID))
+			homeDir, err := getExecUserHome(ctx, l.rootProcArgs.MountNamespace, uint32(l.rootProcArgs.Credentials.RealKUID))
 			if err != nil {
 				return fmt.Errorf("error reading exec user: %v", err)
 			}
@@ -685,7 +688,7 @@ func (l *Loader) startContainer(spec *specs.Spec, conf *Config, cid string, file
 	}
 
 	mntr := newContainerMounter(spec, cid, goferFDs, l.k, l.mountHints)
-	if err := mntr.setupFS(ctx, conf, &procArgs, creds); err != nil {
+	if err := mntr.setupChildContainer(conf, &procArgs); err != nil {
 		return fmt.Errorf("configuring container FS: %v", err)
 	}
 
@@ -756,22 +759,14 @@ func (l *Loader) executeAsync(args *control.ExecArgs) (kernel.ThreadID, error) {
 		return 0, fmt.Errorf("no such container: %q", args.ContainerID)
 	}
 
-	// Get the container Root Dirent and MountNamespace from the Task.
+	// Get the container MountNamespace from the Task.
 	tg.Leader().WithMuLocked(func(t *kernel.Task) {
-		// FSContext.RootDirectory() will take an extra ref for us.
-		args.Root = t.FSContext().RootDirectory()
-
 		// task.MountNamespace() does not take a ref, so we must do so
 		// ourselves.
 		args.MountNamespace = t.MountNamespace()
 		args.MountNamespace.IncRef()
 	})
-	defer func() {
-		if args.Root != nil {
-			args.Root.DecRef()
-		}
-		args.MountNamespace.DecRef()
-	}()
+	defer args.MountNamespace.DecRef()
 
 	// Start the process.
 	proc := control.Proc{Kernel: l.k}