vfs: FsNode::release() implementation and weak ref to VFS node in file descriptors

This commit is contained in:
TheOddGarlic 2022-08-04 09:01:34 +03:00
parent 2a163a55ee
commit 600a81adf7
3 changed files with 61 additions and 33 deletions

View file

@ -4,12 +4,13 @@
* SPDX-License-Identifier: MPL-2.0
*/
use alloc::sync::Arc;
use ext2::fs::{sync::Synced, Ext2};
use ext2::sector::SectorSize;
use ext2::volume::Volume;
use super::errors::FsError;
use super::{FsResult as Result, StorageDevice, DirectoryEntry, FsNode, FileDescriptor};
use super::{DirectoryEntry, FileDescriptor, FsNode, FsResult as Result, StorageDevice};
pub struct Ext2StorageDevice<S, V>
where
@ -36,32 +37,33 @@ where
S: SectorSize + Send,
V: Volume<u8, S> + Send,
{
fn open(&self, node: &super::FsNode /* TODO: flags */) -> Result<FileDescriptor> {
fn open(&self, node: Arc<FsNode> /* TODO: flags */) -> Result<FileDescriptor> {
let inode = self
.fs
.inode_nth(node.inode as usize)
.ok_or_else(|| FsError::InodeNotFound)?;
Ok(FileDescriptor::new(node.flags, inode.size(), node.inode))
Ok(FileDescriptor::new(Arc::downgrade(&node), node.flags, inode.size(), node.inode))
}
fn release(&self, node: &super::FsNode) -> Result<()> {
fn release(&self, _node: FsNode) -> Result<()> {
// TODO: flush to disk and whatnot
Ok(())
}
fn read(&self, _node: &FsNode, _offset: usize, _size: usize) -> Result<Box<[u8]>> {
todo!()
}
fn read(&self, node: &super::FsNode, offset: usize, size: usize) -> Result<Box<[u8]>> {
fn write(&self, _node: &FsNode, _offset: usize, _buffer: Box<[u8]>) -> Result<()> {
todo!()
}
fn write(&self, node: &super::FsNode, offset: usize, buffer: Box<[u8]>) -> Result<()> {
fn read_dir(&self, _node: &FsNode, _index: usize) -> Result<DirectoryEntry> {
todo!()
}
fn read_dir(&self, node: &super::FsNode, index: usize) -> Result<DirectoryEntry> {
todo!()
}
fn find_dir(&self, node: &super::FsNode, name: &str) -> Result<FsNode> {
fn find_dir(&self, _node: &FsNode, _name: &str) -> Result<FsNode> {
todo!()
}
}

View file

@ -7,7 +7,7 @@
pub mod errors;
pub mod ext2;
use alloc::rc::Weak;
use alloc::sync::{Weak, Arc};
use bitflags::bitflags;
use crate::{handle::Handle, KERNEL_STATE};
@ -21,8 +21,8 @@ pub trait StorageDevice
where
Self: Send,
{
fn open(&self, node: &FsNode /* TODO: flags */) -> Result<FileDescriptor>;
fn release(&self, node: &FsNode) -> Result<()>;
fn open(&self, node: Arc<FsNode> /* TODO: flags */) -> Result<FileDescriptor>;
fn release(&self, node: FsNode) -> Result<()>;
fn read(&self, node: &FsNode, offset: usize, size: usize) -> Result<Box<[u8]>>;
fn write(&self, node: &FsNode, offset: usize, buffer: Box<[u8]>) -> Result<()>;
fn read_dir(&self, node: &FsNode, index: usize) -> Result<DirectoryEntry>;
@ -34,10 +34,10 @@ where
/// VFS nodes are created whenever a file that doesn't have an open VFS node is
/// opened. When there are no open file descriptors to a file, the associated
/// VFS node is dropped.
#[derive(Debug)]
pub struct FsNode {
flags: FsFlags,
length: usize, // in bytes
fd_count: usize, // count of open file descriptors
inode: usize, // implementation specific identifier for the node
device_handle: Handle, // uniquely assigned device handle
ptr: Weak<FsNode>, // used by mountpoints and symlinks
@ -56,7 +56,6 @@ impl FsNode {
Self {
flags,
length,
fd_count: 0,
inode,
device_handle,
ptr,
@ -65,27 +64,31 @@ impl FsNode {
/// This method opens a new file descriptor for this VFS node.
// TODO: make this take flags
pub fn open(&mut self) -> Result<Handle> {
let state = KERNEL_STATE.lock();
pub fn open(self: Arc<Self>) -> Result<Handle> {
let mut state = KERNEL_STATE.lock();
let device = state
.get_storage_device(self.device_handle)
.ok_or_else(|| FsError::InvalidDevice)?;
let fd = device.open(self)?;
let mut kernel_state = KERNEL_STATE.lock();
let handle = kernel_state.add_file_descriptor(fd);
let handle = state.open_file_descriptor(fd);
Ok(handle)
}
/// This method is for closing the VFS node, which is done when no open file
/// descriptors for this file are left.
pub fn release(&self) -> Result<()> {
/// This method is for closing the VFS node, which is usually done when no
/// open file descriptors for this file are left. File descriptors have
/// weak references to the VFS node, meaning it is okay to close the VFS
/// node before all file descriptors are closed.
pub fn release(self) -> Result<()> {
let state = KERNEL_STATE.lock();
let device = state
.get_storage_device(self.device_handle)
.ok_or_else(|| FsError::InvalidDevice)?;
device.release(self)
device.release(self)?;
// self is moved into device.release, and at the end of it, self should
// be dropped.
Ok(())
}
/// This method reads from the VFS node without opening a new file
@ -131,6 +134,12 @@ impl FsNode {
}
}
impl Drop for FsNode {
fn drop(&mut self) {
trace!("dropping: {self:#?}")
}
}
bitflags! {
/// Flags associated with VFS nodes and file descriptors
///
@ -147,25 +156,38 @@ bitflags! {
}
/// A file descriptor.
#[derive(Debug)]
pub struct FileDescriptor {
vfs_node: Weak<FsNode>, // ptr to the associated VFS node
flags: FsFlags,
length: usize, // in bytes
inode: usize, // implementation specific identifier for the node
// TODO: permissions mask
// TODO: owning user/group
// TODO: read file position?
// FIXME: I'm not sure if this needs to have a ptr to the VFS node,
// figure that out.
inode: usize, // implementation specific identifier for the node
// TODO: permissions mask
// TODO: owning user/group
// TODO: read file position?
}
impl FileDescriptor {
fn new(flags: FsFlags, length: usize, inode: usize) -> Self {
fn new(vfs_node: Weak<FsNode>, flags: FsFlags, length: usize, inode: usize) -> Self {
Self {
vfs_node,
flags,
length,
inode,
}
}
/// This method is for closing the file descriptor.
pub fn close(fd_handle: Handle) {
let mut state = KERNEL_STATE.lock();
state.close_file_descriptor(fd_handle);
}
}
impl Drop for FileDescriptor {
fn drop(&mut self) {
trace!("dropping: {self:#?}")
}
}
pub struct DirectoryEntry {

View file

@ -2,7 +2,7 @@ use hashbrown::HashMap;
use spin::Lazy;
use crate::{
filesystem::{StorageDevice, FileDescriptor},
filesystem::{FileDescriptor, StorageDevice},
handle::{Handle, HandleResource},
};
@ -40,12 +40,16 @@ impl KernelInternalState {
self.storage_devices.get(&handle).map(|d| &**d)
}
pub fn add_file_descriptor(&mut self, fd: FileDescriptor) -> Handle {
pub fn open_file_descriptor(&mut self, fd: FileDescriptor) -> Handle {
let handle = Handle::new(HandleResource::FileDescriptor);
self.fd_table.insert(handle, fd);
handle
}
pub fn close_file_descriptor(&mut self, fd_handle: Handle) {
self.fd_table.remove(&fd_handle);
}
pub fn shutdown(&mut self) {
self.should_shutdown = true;
}