Some work on FUSE#306
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I wanted to experiment with exporting my session transcripts, here's the main one for this https://gist.github.com/cgwalters/36736a05e572a80f208af8f8cb9b0822 |
fuser 0.17 is needed to support multithreaded FUSE sessions: the new API requires `Filesystem: Send + Sync + 'static`, which forces proper Arc-based ownership of the filesystem state and makes it possible to safely hand the implementation to multiple worker threads. The breaking API changes and how they are addressed: - `&self` instead of `&mut self` on all trait methods: the only mutable state (open file handles) is now protected by a Mutex. - New newtypes (INodeNo, FileHandle, LockOwner, Generation) and bitflags (OpenFlags, FopenFlags) — updated at call sites. - readdir/read offsets changed from i64 to u64. - Session::from_fd now takes SessionACL + Config separately. - Session::run() is no longer public; replaced by spawn().join(). - reply.error() takes fuser::Errno instead of raw i32. To satisfy the `'static` bound, serve_tree_fuse() now takes `Arc<FileSystem>` and `Arc<Repository>`. A pre-built flat Vec<InodeData> (indexed by ino-1) replaces the old HashMap<Ino, InodeRef<'a>>, removing the lifetime that was incompatible with `'static`. An InodeLookup index (path→ino for dirs, LeafId→ino for leaves) handles child ino resolution without raw pointers. Assisted-by: OpenCode (claude-sonnet-4-6) Signed-off-by: Colin Walters <walters@verbum.org>
Wire the composefs-fuse crate into cfsctl behind a new `fuse` cargo
feature (on by default). The FUSE implementation supports readdirplus,
multithreaded serving via FUSE_DEV_IOC_CLONE, FOPEN_KEEP_CACHE, and
optional passthrough (Linux 6.9+, root only) for kernel-bypass reads on
external object files.
CLI surface:
- `cfsctl mount --fuse[=passthrough] [--raw-image]` serves an image
over FUSE instead of doing a kernel composefs mount. `--raw-image`
reads a bare EROFS file from disk rather than looking up a repo image.
This replaces the old `fuse-serve` subcommand; all mount paths now
live under `mount`.
- `cfsctl oci mount --fuse[=passthrough]` likewise for OCI images.
Varlink surface — the single `Mount`/`OciMount` methods now always
return a detached mount fd via SCM_RIGHTS, for both kernel and FUSE
backends. A new `MountPath`/`OciMountPath` pair handles the attach-to-
a-path case server-side (blocking until the FUSE session ends unless
`wait=false`). This makes FUSE mounts a proper first-class path: the
caller gets the fd and can move_mount it wherever it likes, with the
FUSE server running in the background for as long as the fd is held.
Also adds `erofs_fd_to_filesystem` in composefs-fuse to replace the
open-coded open_image → read_to_end → erofs_to_filesystem pattern that
appeared at every call site.
The privileged_fuse_dumpfile_roundtrip integration test spawns
`cfsctl mount --raw-image --fuse`, polls for mount readiness via st_dev
change, and compares the dumpfile produced over the FUSE mount against
the expected output from write_dumpfile.
Assisted-by: OpenCode (claude-sonnet-4-6)
Signed-off-by: Colin Walters <walters@verbum.org>
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