Refactor `Metadata`'s fields and document them.

Besides, change `MajorId`'s lower bound to 0, which is used to
represents a invalid or absent device (pseudo filesystems).

Cargo.lock

@@ -722,6 +722,8 @@ name = "device-id"
 version = "0.1.0"
 dependencies = [
  "aster-util",
+ "id-alloc",
+ "spin",
 ]
 
 [[package]]

kernel/libs/device-id/Cargo.toml

@@ -7,6 +7,8 @@ edition.workspace = true
 
 [dependencies]
 aster-util.workspace = true
+id-alloc.workspace = true
+spin.workspace = true
 
 [lints]
 workspace = true

kernel/libs/device-id/src/lib.rs

@@ -13,6 +13,61 @@
 #![deny(unsafe_code)]
 
 use aster_util::ranged_integer::{RangedU16, RangedU32};
+use id_alloc::IdAlloc;
+use spin::{Mutex, Once};
+
+pub struct PseudoFSDeviceIdAllocator {
+    minor_allocator: Mutex<IdAlloc>,
+}
+
+/// An allocator for pseudo filesystems (no backing block device) device ID.
+///
+/// This follows the Linux convention where pseudo filesystems use major=0
+/// and dynamically allocate minor numbers (starting from 1) to distinguish different
+/// pseudo filesystem instances.
+///
+/// Reference: <https://elixir.bootlin.com/linux/v6.18/source/fs/super.c#L1242-L1271>
+impl PseudoFSDeviceIdAllocator {
+    fn new() -> Self {
+        let mut minor_allocator = IdAlloc::with_capacity(MinorId::MAX.get() as usize + 1);
+        // Mark 0 as allocated to ensure minor numbers start from 1.
+        let _ = minor_allocator.alloc_specific(0);
+
+        Self {
+            minor_allocator: Mutex::new(minor_allocator),
+        }
+    }
+
+    /// Allocate a device ID for pseudo filesystems.
+    /// Returns `None` if minor number allocation fails (exhausted).
+    ///
+    /// # Panics
+    ///
+    /// Panics if the allocator was not initialized.
+    pub fn allocate(&self) -> DeviceId {
+        let major = MajorId::new(0);
+        let minor = self.minor_allocator.lock().alloc().unwrap() as u32;
+
+        DeviceId::new(major, MinorId::new(minor))
+    }
+
+    /// Free a dynamically allocated pseudo filesystem device ID.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the device ID's major is not 0.
+    pub fn release(&mut self, id: DeviceId) {
+        debug_assert!(id.major().get() == 0);
+
+        self.minor_allocator.lock().free(id.minor().get() as usize);
+    }
+}
+
+pub static PSEUDO_FS_DEVICE_ID_ALLOCATOR: Once<PseudoFSDeviceIdAllocator> = Once::new();
+
+pub fn init() {
+    PSEUDO_FS_DEVICE_ID_ALLOCATOR.call_once(PseudoFSDeviceIdAllocator::new);
+}
 
 /// A device ID, embedding the major ID and minor ID.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -24,6 +79,11 @@ impl DeviceId {
         Self(((major.get() as u32) << 20) | minor.get())
     }
 
+    /// FIXME: just a placeholder for now.
+    pub const fn none() -> Self {
+        Self(0)
+    }
+
     /// Returns the encoded `u32` value.
     pub fn to_raw(&self) -> u32 {
         self.0
@@ -38,6 +98,11 @@ impl DeviceId {
     pub fn minor(&self) -> MinorId {
         MinorId::new(self.0 & 0xf_ffff)
     }
+
+    /// Checks if the container device is valid (major != 0).
+    pub fn has_valid_container(&self) -> bool {
+        self.major().get() != 0
+    }
 }
 
 impl DeviceId {
@@ -92,10 +157,13 @@ const MAX_MINOR_ID: u32 = 0x000f_ffff;
 
 /// The major component of a device ID.
 ///
-/// A major ID is a non-zero, 12-bit integer, thus falling in the range of `1..(1u16 << 12)`.
+/// A major ID is a 12-bit integer, thus falling in the range of `0..(1u16 << 12)`.
+///
+/// - **0**: Represents an invalid or absent device (used for pseudo filesystems)
+/// - **1-4095**: Valid major device numbers
 ///
 /// Reference: <https://elixir.bootlin.com/linux/v6.13/source/include/linux/kdev_t.h#L10>.
-pub type MajorId = RangedU16<1, MAX_MAJOR_ID>;
+pub type MajorId = RangedU16<0, MAX_MAJOR_ID>;
 
 /// The minor component of a device ID.
 ///

kernel/src/fs/devpts/mod.rs

@@ -239,27 +239,27 @@ impl Inode for RootInode {
     }
 
     fn atime(&self) -> Duration {
-        self.metadata.read().atime
+        self.metadata.read().last_access_at
     }
 
     fn set_atime(&self, time: Duration) {
-        self.metadata.write().atime = time;
+        self.metadata.write().last_access_at = time;
     }
 
     fn mtime(&self) -> Duration {
-        self.metadata.read().mtime
+        self.metadata.read().last_modify_at
     }
 
     fn set_mtime(&self, time: Duration) {
-        self.metadata.write().mtime = time;
+        self.metadata.write().last_modify_at = time;
     }
 
     fn ctime(&self) -> Duration {
-        self.metadata.read().ctime
+        self.metadata.read().last_meta_change_at
     }
 
     fn set_ctime(&self, time: Duration) {
-        self.metadata.write().ctime = time;
+        self.metadata.write().last_meta_change_at = time;
     }
 
     fn create(&self, name: &str, type_: InodeType, mode: InodeMode) -> Result<Arc<dyn Inode>> {

kernel/src/fs/devpts/ptmx.rs

@@ -121,27 +121,27 @@ impl Inode for Ptmx {
     }
 
     fn atime(&self) -> Duration {
-        self.metadata.read().atime
+        self.metadata.read().last_access_at
     }
 
     fn set_atime(&self, time: Duration) {
-        self.metadata.write().atime = time;
+        self.metadata.write().last_access_at = time;
     }
 
     fn mtime(&self) -> Duration {
-        self.metadata.read().mtime
+        self.metadata.read().last_modify_at
     }
 
     fn set_mtime(&self, time: Duration) {
-        self.metadata.write().mtime = time;
+        self.metadata.write().last_modify_at = time;
     }
 
     fn ctime(&self) -> Duration {
-        self.metadata.read().ctime
+        self.metadata.read().last_meta_change_at
     }
 
     fn set_ctime(&self, time: Duration) {
-        self.metadata.write().ctime = time;
+        self.metadata.write().last_meta_change_at = time;
     }
 
     fn fs(&self) -> Arc<dyn FileSystem> {

kernel/src/fs/devpts/slave.rs

@@ -120,27 +120,27 @@ impl Inode for PtySlaveInode {
     }
 
     fn atime(&self) -> Duration {
-        self.metadata.read().atime
+        self.metadata.read().last_access_at
     }
 
     fn set_atime(&self, time: Duration) {
-        self.metadata.write().atime = time;
+        self.metadata.write().last_access_at = time;
     }
 
     fn mtime(&self) -> Duration {
-        self.metadata.read().mtime
+        self.metadata.read().last_modify_at
     }
 
     fn set_mtime(&self, time: Duration) {
-        self.metadata.write().mtime = time;
+        self.metadata.write().last_modify_at = time;
     }
 
     fn ctime(&self) -> Duration {
-        self.metadata.read().ctime
+        self.metadata.read().last_meta_change_at
     }
 
     fn set_ctime(&self, time: Duration) {
-        self.metadata.write().ctime = time;
+        self.metadata.write().last_meta_change_at = time;
     }
 
     fn fs(&self) -> Arc<dyn FileSystem> {

kernel/src/fs/exfat/inode.rs

@@ -12,6 +12,7 @@ use aster_block::{
     bio::{BioDirection, BioSegment, BioWaiter},
     id::{Bid, BlockId},
 };
+use device_id::DeviceId;
 use ostd::mm::{Segment, VmIo, io_util::HasVmReaderWriter};
 
 use super::{
@@ -1358,21 +1359,20 @@ impl Inode for ExfatInode {
         };
 
         Metadata {
-            dev: 0,
             ino: inner.ino,
             size: inner.size,
-            blk_size,
+            optimal_block_size: blk_size,
-            blocks: inner.size.div_ceil(blk_size),
+            nr_sectors_allocated: inner.size.div_ceil(blk_size),
-            atime: inner.atime.as_duration().unwrap_or_default(),
+            last_access_at: inner.atime.as_duration().unwrap_or_default(),
-            mtime: inner.mtime.as_duration().unwrap_or_default(),
+            last_modify_at: inner.mtime.as_duration().unwrap_or_default(),
-            ctime: inner.ctime.as_duration().unwrap_or_default(),
+            last_meta_change_at: inner.ctime.as_duration().unwrap_or_default(),
             type_: inner.inode_type,
             mode: inner.make_mode(),
-            nlinks,
+            nr_hard_links: nlinks,
             uid: Uid::new(inner.fs().mount_option().fs_uid as u32),
             gid: Gid::new(inner.fs().mount_option().fs_gid as u32),
-            //real device
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
-            rdev: 0,
+            self_dev_id: None,
         }
     }
 

kernel/src/fs/ext2/inode.rs

@@ -6,6 +6,7 @@
 use alloc::{borrow::ToOwned, rc::Rc};
 use core::sync::atomic::{AtomicUsize, Ordering};
 
+use device_id::DeviceId;
 use inherit_methods_macro::inherit_methods;
 use ostd::{const_assert, mm::io_util::HasVmReaderWriter};
 
@@ -106,20 +107,24 @@ impl Inode {
         let inner = self.inner.read();
         let id = self.fs.upgrade().unwrap().block_device().id();
         Metadata {
-            dev: id.as_encoded_u64(),
             ino: self.ino() as _,
             size: inner.file_size() as _,
-            blk_size: BLOCK_SIZE,
+            optimal_block_size: BLOCK_SIZE,
-            blocks: inner.blocks_count() as _,
+            nr_sectors_allocated: inner.blocks_count() as _,
-            atime: inner.atime(),
+            last_access_at: inner.atime(),
-            mtime: inner.mtime(),
+            last_modify_at: inner.mtime(),
-            ctime: inner.ctime(),
+            last_meta_change_at: inner.ctime(),
             type_: self.type_,
             mode: InodeMode::from(inner.file_perm()),
-            nlinks: inner.hard_links() as _,
+            nr_hard_links: inner.hard_links() as _,
             uid: Uid::new(inner.uid()),
             gid: Gid::new(inner.gid()),
-            rdev: self.device_id(),
+            container_dev_id: id,
+            self_dev_id: if self.device_id() != 0 {
+                DeviceId::from_encoded_u64(self.device_id())
+            } else {
+                None
+            },
         }
     }
 

kernel/src/fs/mod.rs

@@ -34,6 +34,7 @@ use crate::{
 };
 
 pub fn init() {
+    device_id::init();
     registry::init();
 
     sysfs::init();

kernel/src/fs/path/dentry.rs

@@ -371,7 +371,7 @@ impl DirDentry<'_> {
 
         dir_inode.unlink(name)?;
 
-        let nlinks = child_inode.metadata().nlinks;
+        let nlinks = child_inode.metadata().nr_hard_links;
         fs::notify::on_link_count(&child_inode);
         if nlinks == 0 {
             // FIXME: `DELETE_SELF` should be generated after closing the last FD.
@@ -422,7 +422,7 @@ impl DirDentry<'_> {
 
         dir_inode.rmdir(name)?;
 
-        let nlinks = child_inode.metadata().nlinks;
+        let nlinks = child_inode.metadata().nr_hard_links;
         if nlinks == 0 {
             // FIXME: `DELETE_SELF` should be generated after closing the last FD.
             fs::notify::on_inode_removed(&child_inode);

kernel/src/fs/procfs/template/mod.rs

@@ -58,27 +58,27 @@ impl Common {
     }
 
     pub fn atime(&self) -> Duration {
-        self.metadata.read().atime
+        self.metadata.read().last_access_at
     }
 
     pub fn set_atime(&self, time: Duration) {
-        self.metadata.write().atime = time;
+        self.metadata.write().last_access_at = time;
     }
 
     pub fn mtime(&self) -> Duration {
-        self.metadata.read().mtime
+        self.metadata.read().last_modify_at
     }
 
     pub fn set_mtime(&self, time: Duration) {
-        self.metadata.write().mtime = time;
+        self.metadata.write().last_modify_at = time;
     }
 
     pub fn ctime(&self) -> Duration {
-        self.metadata.read().ctime
+        self.metadata.read().last_meta_change_at
     }
 
     pub fn set_ctime(&self, time: Duration) {
-        self.metadata.write().ctime = time;
+        self.metadata.write().last_meta_change_at = time;
     }
 
     pub fn mode(&self) -> Result<InodeMode> {

kernel/src/fs/pseudofs.rs

@@ -6,6 +6,7 @@ use core::{
     time::Duration,
 };
 
+use device_id::DeviceId;
 use spin::Once;
 
 use super::utils::{Extension, InodeIo, StatusFlags};
@@ -372,20 +373,20 @@ impl PseudoInode {
         let type_ = InodeType::from(type_);
 
         let metadata = Metadata {
-            dev: 0,
             ino,
             size: 0,
-            blk_size: aster_block::BLOCK_SIZE,
+            optimal_block_size: aster_block::BLOCK_SIZE,
-            blocks: 0,
+            nr_sectors_allocated: 0,
-            atime: now,
+            last_access_at: now,
-            mtime: now,
+            last_modify_at: now,
-            ctime: now,
+            last_meta_change_at: now,
             type_,
             mode,
-            nlinks: 1,
+            nr_hard_links: 1,
             uid,
             gid,
-            rdev: 0,
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
+            self_dev_id: None,
         };
 
         PseudoInode {
@@ -462,7 +463,7 @@ impl Inode for PseudoInode {
 
         let mut meta = self.metadata.lock();
         meta.mode = mode;
-        meta.ctime = now();
+        meta.last_meta_change_at = now();
         Ok(())
     }
 
@@ -473,7 +474,7 @@ impl Inode for PseudoInode {
     fn set_owner(&self, uid: Uid) -> Result<()> {
         let mut meta = self.metadata.lock();
         meta.uid = uid;
-        meta.ctime = now();
+        meta.last_meta_change_at = now();
         Ok(())
     }
 
@@ -484,32 +485,32 @@ impl Inode for PseudoInode {
     fn set_group(&self, gid: Gid) -> Result<()> {
         let mut meta = self.metadata.lock();
         meta.gid = gid;
-        meta.ctime = now();
+        meta.last_meta_change_at = now();
         Ok(())
     }
 
     fn atime(&self) -> Duration {
-        self.metadata.lock().atime
+        self.metadata.lock().last_access_at
     }
 
     fn set_atime(&self, time: Duration) {
-        self.metadata.lock().atime = time;
+        self.metadata.lock().last_access_at = time;
     }
 
     fn mtime(&self) -> Duration {
-        self.metadata.lock().mtime
+        self.metadata.lock().last_modify_at
     }
 
     fn set_mtime(&self, time: Duration) {
-        self.metadata.lock().mtime = time;
+        self.metadata.lock().last_modify_at = time;
     }
 
     fn ctime(&self) -> Duration {
-        self.metadata.lock().ctime
+        self.metadata.lock().last_meta_change_at
     }
 
     fn set_ctime(&self, time: Duration) {
-        self.metadata.lock().ctime = time;
+        self.metadata.lock().last_meta_change_at = time;
     }
 
     fn open(

kernel/src/fs/ramfs/fs.rs

@@ -1170,20 +1170,24 @@ impl Inode for RamInode {
         let rdev = self.inner.device_id().unwrap_or(0);
         let inode_metadata = self.metadata.lock();
         Metadata {
-            dev: 0,
             ino: self.ino as _,
             size: inode_metadata.size,
-            blk_size: BLOCK_SIZE,
+            optimal_block_size: BLOCK_SIZE,
-            blocks: inode_metadata.blocks,
+            nr_sectors_allocated: inode_metadata.blocks,
-            atime: inode_metadata.atime,
+            last_access_at: inode_metadata.atime,
-            mtime: inode_metadata.mtime,
+            last_modify_at: inode_metadata.mtime,
-            ctime: inode_metadata.ctime,
+            last_meta_change_at: inode_metadata.ctime,
             type_: self.typ,
             mode: inode_metadata.mode,
-            nlinks: inode_metadata.nlinks,
+            nr_hard_links: inode_metadata.nlinks,
             uid: inode_metadata.uid,
             gid: inode_metadata.gid,
-            rdev,
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
+            self_dev_id: if rdev == 0 {
+                None
+            } else {
+                DeviceId::from_encoded_u64(rdev)
+            },
         }
     }
 

kernel/src/fs/utils/inode.rs

@@ -6,6 +6,7 @@ use alloc::boxed::ThinBox;
 use core::time::Duration;
 
 use core2::io::{Error as IoError, ErrorKind as IoErrorKind, Result as IoResult, Write};
+use device_id::DeviceId;
 use ostd::task::Task;
 use spin::Once;
 
@@ -124,101 +125,177 @@ impl From<AccessMode> for Permission {
     }
 }
 
+/// File metadata, providing detailed information about an inode.
+///
+/// Asterinas's type-safe counterparts for Linux's `struct stat`.
 #[derive(Debug, Clone, Copy)]
 pub struct Metadata {
-    pub dev: u64,
+    /// The inode number, which uniquely identifies the file within the filesystem.
+    ///
+    /// Corresponds to `st_ino`.
     pub ino: u64,
+
+    /// The size of the inode.
+    ///
+    /// The interpretation depends on `inode_type`:
+    /// - **Regular File**: The total length of the file content.
+    /// - **Directory**: The size of the directory's internal table (usually a multiple of block size).
+    /// - **Symbolic Link**: The length of the target pathname.
+    /// - **Device/Socket/FIFO**: Usually zero.
+    ///
+    /// Corresponds to `st_size`.
     pub size: usize,
-    pub blk_size: usize,
+
-    pub blocks: usize,
+    /// The optimal block size for filesystem I/O operations.
-    pub atime: Duration,
+    ///
-    pub mtime: Duration,
+    /// Corresponds to `st_blksize`.
-    pub ctime: Duration,
+    pub optimal_block_size: usize,
+
+    /// Number of 512-byte sectors allocated for the inode on disk.
+    ///
+    /// Corresponds to `st_blocks`.
+    ///
+    /// This represents physical usage.
+    /// For sparse files (those having holes), `size` is greater than this field.
+    /// For files with preallocated blocks (`FALLOC_FL_KEEP_SIZE`),
+    /// `size` is smaller than this field.
+    pub nr_sectors_allocated: usize,
+
+    /// The timestamp of the last access to the inode's data.
+    ///
+    /// Corresponds to `st_atime`.
+    pub last_access_at: Duration,
+
+    /// The timestamp of the last modification to the inode's content.
+    ///
+    /// Corresponds to `st_mtime`.
+    pub last_modify_at: Duration,
+
+    /// The timestamp of the last change to the inode's metadata.
+    ///
+    /// This is updated when permissions, ownership, or link count change,
+    /// not just when the inode content is modified.
+    ///
+    /// Corresponds to `st_ctime`.
+    pub last_meta_change_at: Duration,
+
+    /// The type of the inode (e.g., regular file, directory, symlink).
+    ///
+    /// Derived from the file type bits of `st_mode` (using the `S_IFMT` mask).
     pub type_: InodeType,
+
+    /// The inode mode, representing access permissions.
+    ///
+    /// Derived from the permission bits of `st_mode`.
     pub mode: InodeMode,
-    pub nlinks: usize,
+
+    /// The number of hard links pointing to this inode.
+    ///
+    /// Corresponds to `st_nlink`.
+    pub nr_hard_links: usize,
+
+    /// The User ID (UID) of the inode's owner.
+    ///
+    /// Corresponds to `st_uid`.
     pub uid: Uid,
+
+    /// The Group ID (GID) of the inode's owner.
+    ///
+    /// Corresponds to `st_gid`.
     pub gid: Gid,
-    pub rdev: u64,
+
+    /// The ID of the device containing the inode.
+    ///
+    /// For persisted files, this device could be a on-disk partition or a logical volume (with RAID).
+    /// For pseudo files (e.g., those on sockfs), this device is also "pseudo".
+    ///
+    /// Corresponds to `st_dev`.
+    pub container_dev_id: DeviceId,
+
+    /// The device ID of the inode itself, if this inode represents a special device file (character or block).
+    ///
+    /// Corresponds to `st_rdev`.
+    pub self_dev_id: Option<DeviceId>,
 }
 
 impl Metadata {
     pub fn new_dir(ino: u64, mode: InodeMode, blk_size: usize) -> Self {
         let now = RealTimeCoarseClock::get().read_time();
         Self {
-            dev: 0,
             ino,
             size: 2,
-            blk_size,
+            optimal_block_size: blk_size,
-            blocks: 1,
+            nr_sectors_allocated: 1,
-            atime: now,
+            last_access_at: now,
-            mtime: now,
+            last_modify_at: now,
-            ctime: now,
+            last_meta_change_at: now,
             type_: InodeType::Dir,
             mode,
-            nlinks: 2,
+            nr_hard_links: 2,
             uid: Uid::new_root(),
             gid: Gid::new_root(),
-            rdev: 0,
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
+            self_dev_id: None,
         }
     }
 
     pub fn new_file(ino: u64, mode: InodeMode, blk_size: usize) -> Self {
         let now = RealTimeCoarseClock::get().read_time();
         Self {
-            dev: 0,
             ino,
             size: 0,
-            blk_size,
+            optimal_block_size: blk_size,
-            blocks: 0,
+            nr_sectors_allocated: 0,
-            atime: now,
+            last_access_at: now,
-            mtime: now,
+            last_modify_at: now,
-            ctime: now,
+            last_meta_change_at: now,
             type_: InodeType::File,
             mode,
-            nlinks: 1,
+            nr_hard_links: 1,
             uid: Uid::new_root(),
             gid: Gid::new_root(),
-            rdev: 0,
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
+            self_dev_id: None,
         }
     }
 
     pub fn new_symlink(ino: u64, mode: InodeMode, blk_size: usize) -> Self {
         let now = RealTimeCoarseClock::get().read_time();
         Self {
-            dev: 0,
             ino,
             size: 0,
-            blk_size,
+            optimal_block_size: blk_size,
-            blocks: 0,
+            nr_sectors_allocated: 0,
-            atime: now,
+            last_access_at: now,
-            mtime: now,
+            last_modify_at: now,
-            ctime: now,
+            last_meta_change_at: now,
             type_: InodeType::SymLink,
             mode,
-            nlinks: 1,
+            nr_hard_links: 1,
             uid: Uid::new_root(),
             gid: Gid::new_root(),
-            rdev: 0,
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
+            self_dev_id: None,
         }
     }
+
     pub fn new_device(ino: u64, mode: InodeMode, blk_size: usize, device: &dyn Device) -> Self {
         let now = RealTimeCoarseClock::get().read_time();
         Self {
-            dev: 0,
             ino,
             size: 0,
-            blk_size,
+            optimal_block_size: blk_size,
-            blocks: 0,
+            nr_sectors_allocated: 0,
-            atime: now,
+            last_access_at: now,
-            mtime: now,
+            last_modify_at: now,
-            ctime: now,
+            last_meta_change_at: now,
             type_: InodeType::from(device.type_()),
             mode,
-            nlinks: 1,
+            nr_hard_links: 1,
             uid: Uid::new_root(),
             gid: Gid::new_root(),
-            rdev: device.id().as_encoded_u64(),
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
+            self_dev_id: Some(device.id()),
         }
     }
 }

kernel/src/fs/utils/systree_inode.rs

@@ -12,6 +12,7 @@ use core::time::Duration;
 use aster_systree::{
     SysAttr, SysBranchNode, SysNode, SysNodeId, SysNodeType, SysObj, SysStr, SysSymlink,
 };
+use device_id::DeviceId;
 
 use super::Extension;
 use crate::{
@@ -74,21 +75,21 @@ pub(in crate::fs) trait SysTreeInodeTy: Send + Sync + 'static {
     fn new_metadata(ino: u64, type_: InodeType) -> Metadata {
         let now = RealTimeCoarseClock::get().read_time();
         Metadata {
-            dev: 0,
             ino,
             size: 0,
-            blk_size: 1024,
+            optimal_block_size: 1024,
-            blocks: 0,
+            nr_sectors_allocated: 0,
-            atime: now,
+            last_access_at: now,
-            mtime: now,
+            last_modify_at: now,
-            ctime: now,
+            last_meta_change_at: now,
             type_,
             // The mode field in metadata will not be used
             mode: mkmod!(a=),
-            nlinks: 1,
+            nr_hard_links: 1,
             uid: Uid::new_root(),
             gid: Gid::new_root(),
-            rdev: 0,
+            container_dev_id: DeviceId::none(), // FIXME: placeholder
+            self_dev_id: None,
         }
     }
 
@@ -361,19 +362,19 @@ impl<KInode: SysTreeInodeTy + Send + Sync + 'static> Inode for KInode {
     }
 
     default fn atime(&self) -> Duration {
-        self.metadata().atime
+        self.metadata().last_access_at
     }
 
     default fn set_atime(&self, _time: Duration) {}
 
     default fn mtime(&self) -> Duration {
-        self.metadata().mtime
+        self.metadata().last_modify_at
     }
 
     default fn set_mtime(&self, _time: Duration) {}
 
     default fn ctime(&self) -> Duration {
-        self.metadata().ctime
+        self.metadata().last_meta_change_at
     }
 
     default fn set_ctime(&self, _time: Duration) {}

kernel/src/syscall/mount.rs

@@ -1,7 +1,5 @@
 // SPDX-License-Identifier: MPL-2.0
 
-use device_id::DeviceId;
-
 use super::SyscallReturn;
 use crate::{
     fs::{
@@ -240,7 +238,7 @@ fn get_fs(
             return_errno_with_message!(Errno::ENODEV, "the path is not a device file");
         }
 
-        let id = DeviceId::from_encoded_u64(path.metadata().rdev);
+        let id = path.metadata().self_dev_id;
         let device = id.and_then(aster_block::lookup);
         if device.is_none() {
             return_errno_with_message!(Errno::ENODEV, "the device is not found");

kernel/src/syscall/stat.rs

@@ -175,19 +175,19 @@ struct Stat {
 impl From<Metadata> for Stat {
     fn from(info: Metadata) -> Self {
         Self {
-            st_dev: info.dev,
+            st_dev: info.container_dev_id.as_encoded_u64(),
             st_ino: info.ino,
-            st_nlink: info.nlinks as _,
+            st_nlink: info.nr_hard_links as _,
             st_mode: info.type_ as u32 | info.mode.bits() as u32,
             st_uid: info.uid.into(),
             st_gid: info.gid.into(),
-            st_rdev: info.rdev,
+            st_rdev: info.self_dev_id.map_or(0, |id| id.as_encoded_u64()),
             st_size: info.size as i64,
-            st_blksize: info.blk_size as _,
+            st_blksize: info.optimal_block_size as _,
-            st_blocks: (info.blocks * (info.blk_size / 512)) as i64,
+            st_blocks: info.nr_sectors_allocated as _,
-            st_atime: info.atime.into(),
+            st_atime: info.last_access_at.into(),
-            st_mtime: info.mtime.into(),
+            st_mtime: info.last_modify_at.into(),
-            st_ctime: info.ctime.into(),
+            st_ctime: info.last_meta_change_at.into(),
             ..Default::default()
         }
     }

kernel/src/syscall/statx.rs

@@ -128,8 +128,10 @@ impl Statx {
     fn new(path: &Path) -> Self {
         let info = path.metadata();
 
-        let (stx_dev_major, stx_dev_minor) = device_id::decode_device_numbers(info.dev);
+        let (stx_dev_major, stx_dev_minor) =
-        let (stx_rdev_major, stx_rdev_minor) = device_id::decode_device_numbers(info.rdev);
+            device_id::decode_device_numbers(info.container_dev_id.as_encoded_u64());
+        let (stx_rdev_major, stx_rdev_minor) =
+            device_id::decode_device_numbers(info.self_dev_id.map_or(0, |id| id.as_encoded_u64()));
 
         // TODO: Support more `stx_attributes` flags.
         let stx_attributes_mask = STATX_ATTR_MOUNT_ROOT;
@@ -146,21 +148,21 @@ impl Statx {
         Self {
             // FIXME: All zero fields below are dummy implementations that need to be improved in the future.
             stx_mask,
-            stx_blksize: info.blk_size as u32,
+            stx_blksize: info.optimal_block_size as u32,
             stx_attributes,
-            stx_nlink: info.nlinks as u32,
+            stx_nlink: info.nr_hard_links as u32,
             stx_uid: info.uid.into(),
             stx_gid: info.gid.into(),
             stx_mode: info.type_ as u16 | info.mode.bits(),
             __spare0: [0; 1],
             stx_ino: info.ino,
             stx_size: info.size as u64,
-            stx_blocks: (info.blocks * (info.blk_size / 512)) as u64,
+            stx_blocks: (info.nr_sectors_allocated * (info.optimal_block_size / 512)) as u64,
             stx_attributes_mask,
-            stx_atime: StatxTimestamp::from(info.atime),
+            stx_atime: StatxTimestamp::from(info.last_access_at),
-            stx_btime: StatxTimestamp::from(info.atime),
+            stx_btime: StatxTimestamp::from(info.last_access_at),
-            stx_ctime: StatxTimestamp::from(info.ctime),
+            stx_ctime: StatxTimestamp::from(info.last_meta_change_at),
-            stx_mtime: StatxTimestamp::from(info.ctime),
+            stx_mtime: StatxTimestamp::from(info.last_meta_change_at),
             stx_rdev_major,
             stx_rdev_minor,
             stx_dev_major,

kernel/src/vm/vmar/vm_mapping.rs

@@ -242,7 +242,9 @@ impl VmMapping {
         let offset = self.vmo().map(|vmo| vmo.offset).unwrap_or(0);
         let (dev_major, dev_minor) = self
             .inode()
-            .map(|inode| device_id::decode_device_numbers(inode.metadata().dev))
+            .map(|inode| {
+                device_id::decode_device_numbers(inode.metadata().container_dev_id.as_encoded_u64())
+            })
             .unwrap_or((0, 0));
         let ino = self.inode().map(|inode| inode.ino()).unwrap_or(0);