Merge branch 'master' into async-runtime-takeover

Author: jiangliu

.github/workflows/rust.yml

@@ -59,6 +59,53 @@ jobs:
         sudo -E CARGO=${CARGO_BIN} make smoke-all
         sudo chown -R $(id -u):$(id -g) "${HOME}/.cargo"
 
+  MSRV:
+    # `CI` builds on `stable` only, so nothing notices when a change quietly
+    # needs a newer rustc than the declared `rust-version`; the
+    # trait-object-upcasting requirement slipped in exactly that way. Check
+    # with the declared MSRV instead, on a native runner: `--all-features
+    # --all-targets` covers the async-io paths that needed the bump, plus the
+    # drivers, transports and persist stack on top. The dev-only binaries
+    # under tests/ declare no `rust-version` and track the latest
+    # dev-dependencies, whose MSRV is not ours to promise (today
+    # `simple_logger` 5.2 floors `time` at a release needing rustc 1.88), so
+    # they are excluded; the stable-toolchain jobs still build them (`CI`
+    # runs the benchmark smoke, `xfstests` and `benchmark` build the daemons).
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+    - uses: actions/checkout@v3
+    - name: Cache cargo
+      uses: Swatinem/rust-cache@v2.2.0
+      with:
+        cache-on-failure: true
+        key: ${{ runner.os }}-cargo-msrv
+    - name: Read declared MSRV
+      # Take the MSRV from the root manifest instead of pinning a second
+      # copy here: a pin left behind by a later bump would quietly check a
+      # version nobody declares anymore. Cargo still rejects a member whose
+      # own rust-version exceeds the toolchain, so the crate manifests
+      # cannot drift past what this job checks.
+      id: msrv
+      run: |
+        msrv=$(sed -n 's/^rust-version = "\(.*\)"/\1/p' Cargo.toml | head -1)
+        echo "version=$msrv" >> "$GITHUB_OUTPUT"
+    - name: Install Rust
+      uses: actions-rs/toolchain@v1
+      with:
+        profile: minimal
+        toolchain: ${{ steps.msrv.outputs.version }}
+        override: true
+    - name: Check
+      # No Cargo.lock is tracked, so dependencies are resolved fresh here.
+      # The resolver's default (`allow`) keeps picking versions that need a
+      # newer rustc than the declared MSRV; `fallback` prefers versions the
+      # MSRV can compile, so the job survives a dependency raising its own
+      # rust-version.
+      env:
+        CARGO_RESOLVER_INCOMPATIBLE_RUST_VERSIONS: fallback
+      run: cargo check --workspace --all-features --all-targets --exclude passthrough --exclude overlay --exclude fuse-backend-rs-benchmark
+
   Macos-CI:
     runs-on: macos-latest
     steps:

CHANGELOG.md

@@ -1,6 +1,9 @@
 # Changelog
 ## [Unreleased]
 ### Added
+- `uring_available()` tells whether the kernel lets the process serve FUSE over io_uring: the
+  fuse module's `enable_uring` parameter is on and the process may create an io_uring. Checking
+  it before mounting saves a mount that would fall back to `/dev/fuse`.
 - [254](https://github.com/cloud-hypervisor/fuse-backend-rs/pull/254): Split the library into a layered Cargo workspace and break the layers out into
   their own crates — `fuse-backend-core` (ABI, API/server, buffers),
   `fuse-backend-fusedev` and `fuse-backend-virtiofs` (transports), and
@@ -35,8 +38,20 @@
 - `Server::init_state()` and `Server::restore_init()` let a new server take over a connection
   that another server initialized. `abi::fuse_abi::UNIQUE_RESEND` is the bit that the kernel
   sets in requests it sends again after `notify_resend()`.
+- [269](https://github.com/cloud-hypervisor/fuse-backend-rs/pull/269): `AsyncFileSystem` methods default to calling their `FileSystem`
+  counterparts, so a file system only implements the handlers it serves asynchronously.
+- [269](https://github.com/cloud-hypervisor/fuse-backend-rs/pull/269): `FuseSession::detach()` lazily unmounts a Linux session through `&self`,
+  so the owner of a serving layer can start the teardown while another thread waits in
+  `FuseServing::wait()`.
 
 ### Changed
+- Bump the declared minimum supported Rust version (MSRV) from 1.80 to 1.86.
+  Trait-object upcasting (stabilized in Rust 1.86) is required by the default
+  `AsyncFileSystem` read/write handlers and by the passthrough O_DIRECT relay,
+  so with the `async-io` feature enabled the workspace has not built on older
+  toolchains for a while — the 1.80 declaration was already inaccurate. CI
+  gains an MSRV job that checks the crates declaring `rust-version` with the
+  declared version, so the next accidental bump is caught.
 - The FUSE-over-io_uring transport answers opcodes it doesn't know with ENOSYS instead of EIO.
   Kernels that send `FUSE_STATX` only fall back to `FUSE_GETATTR` after ENOSYS, so `statx()`
   calls that ask for more than the basic fields, like the birth time `stat(1)` shows, failed.
@@ -82,11 +97,16 @@
   and no code in the workspace relied on it.
 
 ### Fixed
+- READDIR and READDIRPLUS answer ENOMEM when the reply can't hold the reply header plus the
+  requested size. The check left out the header, so a writer short by up to 16 bytes started the
+  listing and failed partway.
 - [278](https://github.com/cloud-hypervisor/fuse-backend-rs/pull/278): Treat `EOPNOTSUPP`/`ENOTSUP` and `ENOSYS` from `getxattr` as "not opaque"
   in `Layer::is_opaque()`, so `OverlayFs::import()` no longer aborts when a layer's
   backing filesystem has no xattr support at all (tmpfs answers `EOPNOTSUPP` to
   `user.*` xattrs before Linux 6.12, and a `PassthroughFs` layer with `xattr`
   disabled answers `ENOSYS`).
+- [269](https://github.com/cloud-hypervisor/fuse-backend-rs/pull/269): For a session mounted with `set_target_mntns()`,
+  `FuseSession::umount()` unmounts in that mount namespace. It no longer follows a symlink at the mountpoint.
 
 ### Removed
 - [254](https://github.com/cloud-hypervisor/fuse-backend-rs/pull/254): Drop the vestigial `vhost` and `virtio-bindings` dependencies that the

Cargo.toml

@@ -12,7 +12,7 @@ authors = [
 readme = "README.md"
 license = "Apache-2.0 AND BSD-3-Clause"
 edition = "2018"
-rust-version = "1.80"
+rust-version = "1.86"
 repository = "https://github.com/cloud-hypervisor/fuse-backend-rs"
 homepage = "https://github.com/cloud-hypervisor/"
 

Makefile

@@ -146,7 +146,7 @@ smoke-macos: check-macos
 	${CARGO} test --features="fusedev,fuse-t" -- --nocapture
 
 docker-smoke:
-	docker run --env RUST_BACKTRACE=1 --rm --privileged --volume ${current_dir}:/fuse-rs rust:1.68 sh -c "rustup component add clippy rustfmt; cd /fuse-rs; make smoke-all"
+	docker run --env RUST_BACKTRACE=1 --rm --privileged --volume ${current_dir}:/fuse-rs rust:1.86 sh -c "rustup component add clippy rustfmt; cd /fuse-rs; make smoke-all"
 
 testoverlay:
 	${CARGO} build -p overlay

crates/fuse-backend-core/Cargo.toml

@@ -11,7 +11,7 @@ authors = [
 ]
 license = "Apache-2.0 AND BSD-3-Clause"
 edition = "2018"
-rust-version = "1.80"
+rust-version = "1.86"
 repository = "https://github.com/cloud-hypervisor/fuse-backend-rs"
 homepage = "https://github.com/cloud-hypervisor/"
 readme = "README.md"