1 files changed, 82 insertions, 0 deletions
diff --git a/rust/kernel/src/filesystem.rs b/rust/kernel/src/filesystem.rs
new file mode 100644
index 000000000000..11b415008f68
--- /dev/null
+++ b/rust/kernel/src/filesystem.rs
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+
+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)
+}