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// SPDX-License-Identifier: GPL-2.0
// TODO: `filesystem` is really incomplete -- deletion to be considered
use alloc::boxed::Box;
use core::default::Default;
use core::marker;
use crate::bindings;
use crate::c_types;
use crate::error;
use crate::types::CStr;
pub struct Registration<T: FileSystem> {
_phantom: marker::PhantomData<T>,
ptr: Box<bindings::file_system_type>,
}
// This is safe because Registration doesn't actually expose any methods.
unsafe impl<T> Sync for Registration<T> where T: FileSystem {}
impl<T: FileSystem> Drop for Registration<T> {
fn drop(&mut self) {
unsafe { bindings::unregister_filesystem(&mut *self.ptr) };
}
}
pub trait FileSystem: Sync {
const NAME: &'static CStr;
const FLAGS: FileSystemFlags;
}
bitflags::bitflags! {
pub struct FileSystemFlags: c_types::c_int {
const REQUIRES_DEV = bindings::FS_REQUIRES_DEV as c_types::c_int;
const BINARY_MOUNTDATA = bindings::FS_BINARY_MOUNTDATA as c_types::c_int;
const HAS_SUBTYPE = bindings::FS_HAS_SUBTYPE as c_types::c_int;
const USERNS_MOUNT = bindings::FS_USERNS_MOUNT as c_types::c_int;
const RENAME_DOES_D_MOVE = bindings::FS_RENAME_DOES_D_MOVE as c_types::c_int;
}
}
extern "C" fn fill_super_callback<T: FileSystem>(
_sb: *mut bindings::super_block,
_data: *mut c_types::c_void,
_silent: c_types::c_int,
) -> c_types::c_int {
// T::fill_super(...)
// This should actually create an object that gets dropped by
// file_system_registration::kill_sb. You can point to it with
// sb->s_fs_info.
unimplemented!();
}
extern "C" fn mount_callback<T: FileSystem>(
fs_type: *mut bindings::file_system_type,
flags: c_types::c_int,
_dev_name: *const c_types::c_char,
data: *mut c_types::c_void,
) -> *mut bindings::dentry {
unsafe { bindings::mount_nodev(fs_type, flags, data, Some(fill_super_callback::<T>)) }
}
pub fn register<T: FileSystem>() -> error::KernelResult<Registration<T>> {
let mut fs_registration = Registration {
ptr: Box::new(bindings::file_system_type {
name: T::NAME.as_ptr() as *const i8,
// TODO: proper `THIS_MODULE` handling
owner: core::ptr::null_mut(),
fs_flags: T::FLAGS.bits(),
mount: Some(mount_callback::<T>),
kill_sb: Some(bindings::kill_litter_super),
..Default::default()
}),
_phantom: marker::PhantomData,
};
let result = unsafe { bindings::register_filesystem(&mut *fs_registration.ptr) };
if result != 0 {
return Err(error::Error::from_kernel_errno(result));
}
Ok(fs_registration)
}
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