[libos] Change ROOT_INODE to ROOT_FS

Filesystem should be the owner of its root inode

deps/sefs

@@ -1 +1 @@
-Subproject commit d26132ca7b5a3338046e4b644cb75953981f0feb
+Subproject commit d20c9e40853b59162baff3bc82070a8fa5f28537

src/libos/src/entry.rs

@@ -301,7 +301,7 @@ fn do_exec_thread(libos_tid: pid_t, host_tid: pid_t) -> Result<i32> {
     // sync file system
     // TODO: only sync when all processes exit
     use rcore_fs::vfs::FileSystem;
-    crate::fs::ROOT_INODE.read().unwrap().fs().sync()?;
+    crate::fs::ROOT_FS.read().unwrap().sync()?;
 
     // Not to be confused with the return value of a main function.
     // The exact meaning of status is described in wait(2) man page.

src/libos/src/fs/fs_ops/mount.rs

@@ -22,15 +22,12 @@ pub fn do_mount_rootfs(
     if MOUNT_ONCE.is_completed() {
         return_errno!(EPERM, "rootfs cannot be mounted more than once");
     }
-    let new_root_inode = {
-        let rootfs = open_root_fs_according_to(&user_config.mount, user_key)?;
-        rootfs.root_inode()
-    };
-    mount_nonroot_fs_according_to(&new_root_inode, &user_config.mount, user_key, true)?;
+    let new_rootfs = open_root_fs_according_to(&user_config.mount, user_key)?;
+    mount_nonroot_fs_according_to(&new_rootfs.root_inode(), &user_config.mount, user_key, true)?;
     MOUNT_ONCE.call_once(|| {
-        let mut root_inode = ROOT_INODE.write().unwrap();
-        root_inode.fs().sync().expect("failed to sync old rootfs");
-        *root_inode = new_root_inode;
+        let mut rootfs = ROOT_FS.write().unwrap();
+        rootfs.sync().expect("failed to sync old rootfs");
+        *rootfs = new_rootfs;
         *ENTRY_POINTS.write().unwrap() = user_config.entry_points.to_owned();
     });
     // Write resolv.conf file into mounted file system
@@ -132,11 +129,16 @@ pub fn do_mount(
         }
     };
 
-    let mut root_inode = ROOT_INODE.write().unwrap();
+    let mut rootfs = ROOT_FS.write().unwrap();
     // Should we sync the fs before mount?
-    root_inode.fs().sync()?;
+    rootfs.sync()?;
     let follow_symlink = !flags.contains(MountFlags::MS_NOSYMFOLLOW);
-    mount_nonroot_fs_according_to(&*root_inode, &mount_configs, &user_key, follow_symlink)?;
+    mount_nonroot_fs_according_to(
+        &rootfs.root_inode(),
+        &mount_configs,
+        &user_key,
+        follow_symlink,
+    )?;
     Ok(())
 }
 
@@ -153,11 +155,11 @@ pub fn do_umount(target: &str, flags: UmountFlags) -> Result<()> {
         fs.convert_to_abs_path(target)
     };
 
-    let mut root_inode = ROOT_INODE.write().unwrap();
+    let mut rootfs = ROOT_FS.write().unwrap();
     // Should we sync the fs before umount?
-    root_inode.fs().sync()?;
+    rootfs.sync()?;
     let follow_symlink = !flags.contains(UmountFlags::UMOUNT_NOFOLLOW);
-    umount_nonroot_fs(&*root_inode, &target, follow_symlink)?;
+    umount_nonroot_fs(&rootfs.root_inode(), &target, follow_symlink)?;
     Ok(())
 }
 

src/libos/src/fs/fs_ops/sync.rs

@@ -2,6 +2,6 @@ use super::*;
 
 pub fn do_sync() -> Result<()> {
     debug!("sync:");
-    ROOT_INODE.read().unwrap().fs().sync()?;
+    ROOT_FS.read().unwrap().sync()?;
     Ok(())
 }

src/libos/src/fs/fs_view.rs

@@ -165,17 +165,19 @@ impl FsView {
         if path.len() > 0 && path.as_bytes()[0] == b'/' {
             // absolute path
             let abs_path = path.trim_start_matches('/');
-            let inode = ROOT_INODE
+            let inode = ROOT_FS
                 .read()
                 .unwrap()
+                .root_inode()
                 .lookup_follow(abs_path, MAX_SYMLINKS)?;
             Ok(inode)
         } else {
             // relative path
             let cwd = self.cwd().trim_start_matches('/');
-            let inode = ROOT_INODE
+            let inode = ROOT_FS
                 .read()
                 .unwrap()
+                .root_inode()
                 .lookup_follow(cwd, MAX_SYMLINKS)?
                 .lookup_follow(path, MAX_SYMLINKS)?;
             Ok(inode)

src/libos/src/fs/mod.rs

@@ -31,7 +31,7 @@ pub use self::fs_view::FsView;
 pub use self::host_fd::HostFd;
 pub use self::inode_file::{AsINodeFile, INodeExt, INodeFile};
 pub use self::pipe::PipeType;
-pub use self::rootfs::ROOT_INODE;
+pub use self::rootfs::ROOT_FS;
 pub use self::stdio::{HostStdioFds, StdinFile, StdoutFile};
 pub use self::syscalls::*;
 pub use self::timer_file::{AsTimer, TimerCreationFlags, TimerFile};

src/libos/src/fs/rootfs.rs

@@ -15,29 +15,26 @@ use rcore_fs_unionfs::UnionFS;
 
 lazy_static! {
     /// The root of file system
-    pub static ref ROOT_INODE: RwLock<Arc<dyn INode>> = {
-        fn init_root_inode() -> Result<Arc<dyn INode>> {
+    pub static ref ROOT_FS: RwLock<Arc<dyn FileSystem>> = {
+        fn init_root_fs() -> Result<Arc<dyn FileSystem>> {
             let mount_config = &config::LIBOS_CONFIG.mount;
-            let root_inode = {
             let rootfs = open_root_fs_according_to(mount_config, &None)?;
-                rootfs.root_inode()
-            };
-            mount_nonroot_fs_according_to(&root_inode, mount_config, &None, true)?;
-            Ok(root_inode)
+            mount_nonroot_fs_according_to(&rootfs.root_inode(), mount_config, &None, true)?;
+            Ok(rootfs)
         }
 
-        let root_inode = init_root_inode().unwrap_or_else(|e| {
-            error!("failed to init root inode: {}", e.backtrace());
+        let rootfs = init_root_fs().unwrap_or_else(|e| {
+            error!("failed to init root fs: {}", e.backtrace());
             panic!();
         });
-        RwLock::new(root_inode)
+        RwLock::new(rootfs)
     };
 }
 
 pub fn open_root_fs_according_to(
     mount_configs: &Vec<ConfigMount>,
     user_key: &Option<sgx_key_128bit_t>,
-) -> Result<Arc<MountFS>> {
+) -> Result<Arc<dyn FileSystem>> {
     let root_mount_config = mount_configs
         .iter()
         .find(|m| m.target == Path::new("/") && m.type_ == ConfigMountFsType::TYPE_UNIONFS)