On 23/10/18 09:24AM, Wedson Almeida Filho wrote:
> From: Wedson Almeida Filho <walmeida@xxxxxxxxxxxxx>
>
> This series introduces Rust abstractions that allow page-cache-backed read-only
> file systems to be written in Rust.
>
> There are two file systems that are built on top of these abstractions: tarfs
> and puzzlefs. The former has zero unsafe blocks and is included as a patch in
> this series; the latter is described elsewhere [1]. We limit the functionality
> to the bare minimum needed to implement them.
>
> Rust file system modules can be declared with the `module_fs` macro and are
> required to implement the following functions (which are part of the
> `FileSystem` trait):
>
> impl FileSystem for MyFS {
> fn super_params(sb: &NewSuperBlock<Self>) -> Result<SuperParams<Self::Data>>;
> fn init_root(sb: &SuperBlock<Self>) -> Result<ARef<INode<Self>>>;
> fn read_dir(inode: &INode<Self>, emitter: &mut DirEmitter) -> Result;
> fn lookup(parent: &INode<Self>, name: &[u8]) -> Result<ARef<INode<Self>>>;
> fn read_folio(inode: &INode<Self>, folio: LockedFolio<'_>) -> Result;
> }
>
> They can optionally implement the following:
>
> fn read_xattr(inode: &INode<Self>, name: &CStr, outbuf: &mut [u8]) -> Result<usize>;
> fn statfs(sb: &SuperBlock<Self>) -> Result<Stat>;
>
> They may also choose the type of the data they can attach to superblocks and/or
> inodes.
>
> There a couple of issues that are likely to lead to unsoundness that have to do
> with the unregistration of file systems. I will send separate emails about
> them.
>
> A git tree is available here:
> git://github.com/wedsonaf/linux.git vfs
>
> Web:
> https://github.com/wedsonaf/linux/commits/vfs
I've checked out your branch and but it doesn't compile:
```
$ make LLVM=1 -j4
DESCEND objtool
CALL scripts/checksyscalls.sh
make[4]: 'install_headers' is up to date.
RUSTC L rust/kernel.o
error[E0425]: cannot find function `folio_alloc` in crate `bindings`
--> rust/kernel/folio.rs:43:54
|
43 | let f = ptr::NonNull::new(unsafe { bindings::folio_alloc(bindings::GFP_KERNEL, order) })
| ^^^^^^^^^^^ help: a function with a similar name exists: `__folio_alloc`
|
::: /home/amiculas/work/linux/rust/bindings/bindings_generated.rs:17311:5
|
17311 | / pub fn __folio_alloc(
17312 | | gfp: gfp_t,
17313 | | order: core::ffi::c_uint,
17314 | | preferred_nid: core::ffi::c_int,
17315 | | nodemask: *mut nodemask_t,
17316 | | ) -> *mut folio;
| |___________________- similarly named function `__folio_alloc` defined here
error: aborting due to previous error
For more information about this error, try `rustc --explain E0425`.
make[2]: *** [rust/Makefile:460: rust/kernel.o] Error 1
make[1]: *** [/home/amiculas/work/linux/Makefile:1208: prepare] Error 2
make: *** [Makefile:234: __sub-make] Error 2
```
I'm missing `CONFIG_NUMA`, which seems to guard `folio_alloc`
(include/linux/gfp.h):
```
#ifdef CONFIG_NUMA
struct page *alloc_pages(gfp_t gfp, unsigned int order);
struct folio *folio_alloc(gfp_t gfp, unsigned order);
struct folio *vma_alloc_folio(gfp_t gfp, int order, struct vm_area_struct *vma,
unsigned long addr, bool hugepage);
#else
```
>
> [1]: The PuzzleFS container filesystem: https://lwn.net/Articles/945320/
>
> Wedson Almeida Filho (19):
> rust: fs: add registration/unregistration of file systems
> rust: fs: introduce the `module_fs` macro
> samples: rust: add initial ro file system sample
> rust: fs: introduce `FileSystem::super_params`
> rust: fs: introduce `INode<T>`
> rust: fs: introduce `FileSystem::init_root`
> rust: fs: introduce `FileSystem::read_dir`
> rust: fs: introduce `FileSystem::lookup`
> rust: folio: introduce basic support for folios
> rust: fs: introduce `FileSystem::read_folio`
> rust: fs: introduce `FileSystem::read_xattr`
> rust: fs: introduce `FileSystem::statfs`
> rust: fs: introduce more inode types
> rust: fs: add per-superblock data
> rust: fs: add basic support for fs buffer heads
> rust: fs: allow file systems backed by a block device
> rust: fs: allow per-inode data
> rust: fs: export file type from mode constants
> tarfs: introduce tar fs
>
> fs/Kconfig | 1 +
> fs/Makefile | 1 +
> fs/tarfs/Kconfig | 16 +
> fs/tarfs/Makefile | 8 +
> fs/tarfs/defs.rs | 80 ++
> fs/tarfs/tar.rs | 322 +++++++
> rust/bindings/bindings_helper.h | 13 +
> rust/bindings/lib.rs | 6 +
> rust/helpers.c | 142 ++++
> rust/kernel/error.rs | 6 +-
> rust/kernel/folio.rs | 214 +++++
> rust/kernel/fs.rs | 1290 +++++++++++++++++++++++++++++
> rust/kernel/fs/buffer.rs | 60 ++
> rust/kernel/lib.rs | 2 +
> rust/kernel/mem_cache.rs | 2 -
> samples/rust/Kconfig | 10 +
> samples/rust/Makefile | 1 +
> samples/rust/rust_rofs.rs | 154 ++++
> scripts/generate_rust_analyzer.py | 2 +-
> 19 files changed, 2324 insertions(+), 6 deletions(-)
> create mode 100644 fs/tarfs/Kconfig
> create mode 100644 fs/tarfs/Makefile
> create mode 100644 fs/tarfs/defs.rs
> create mode 100644 fs/tarfs/tar.rs
> create mode 100644 rust/kernel/folio.rs
> create mode 100644 rust/kernel/fs.rs
> create mode 100644 rust/kernel/fs/buffer.rs
> create mode 100644 samples/rust/rust_rofs.rs
>
>
> base-commit: b0bc357ef7a98904600826dea3de79c0c67eb0a7
> --
> 2.34.1
>
