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Build async-io on macOS and report why io-uring isn't available - #270
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AsyncFileReadWriteVolatile used tokio_uring only for IoBuf::bytes_total(), so call FileVolatileBuf::cap() instead. The vfs async handlers used the Linux-only libc::stat64 and VfsOptions::no_open, so use fuse_abi::stat64 and check no_open on Linux only. The umbrella crate now forwards async-io to the transports with pkg?/feature, so async-io alone no longer pulls in the Linux-only virtiofs transport. Signed-off-by: Ilan Joselevich <personal@ilanjoselevich.com>
async-io failed to build on macOS, because it pulled in io-uring on every platform and io-uring only builds on Linux. The code that uses io_uring was already Linux-only. Make io-uring a Linux-only dependency, like tokio-uring. Other platforms run async-io on tokio. The macfuse example gets the AsyncFileSystem impl that async-io requires, and the Makefile builds and tests async-io on macOS. Signed-off-by: Ilan Joselevich <personal@ilanjoselevich.com>
When the io-uring probe failed, set_runtime_type(RuntimeType::Uring) returned "async runtime type is Tokio, not Uring". The probe only logged its reason, so an application couldn't tell a low RLIMIT_MEMLOCK from a seccomp filter. Keep the probe's error and return it from set_runtime_type(), with its kind. The fallback warning includes it too. The test blocks io_uring_setup() with a seccomp filter, and skips where it can't install one, such as under QEMU. Signed-off-by: Ilan Joselevich <personal@ilanjoselevich.com>
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async-ioonly builds on Linux, because it pulls inio-uringon every platform. Most of the async code doesn't need io_uring, and the tokio runtime already serves Linux without it. This buildsasync-ioon macOS, where it runs on tokio.AsyncFileReadWriteVolatileusedtokio_uringonly forIoBuf::bytes_total(), and the Vfs async handlers used the Linux-onlylibc::stat64andVfsOptions::no_open. The umbrella crate forwardsasync-ioto the transports withpkg?/feature, soasync-ioalone no longer pulls in the Linux-only virtiofs transport.io-uringbecomes a Linux-only dependency offuse-backend-core, liketokio-uring. The macfuse example gets theAsyncFileSystemimpl thatasync-iorequires, andmake check-macosbuilds, lints and testsasync-io.set_runtime_type(RuntimeType::Uring)returned "async runtime type is Tokio, not Uring" when the probe failed, and only the log said why. It now returns the probe's error with its kind, so an application can tell a lowRLIMIT_MEMLOCKfrom a seccomp filter. The test blocksio_uring_setup()with a seccomp filter.This changes the umbrella crate's
async-io. It no longer turns on thefusedevandvirtiofstransports, so code that uses items they gate, such asabi::virtio_fs, has to enable them. A crate that depends on a transport crate directly must enable that crate'sasync-iotoo, or its writers fail asynchronous replies withEINVAL.The asynchronous fusedev transport (
FuseDevTask,AsyncFuseServing) stays Linux-only.fuse-backend-fusedev's ownio-uringdependency for thefusedev-uringfeature is unchanged.Tested on Linux 7.2.10 with
make checkand the mount tests in a user namespace. For macOS,cargo check --target aarch64-apple-darwin --testsand clippy pass withfusedev,async-ioandfusedev,fuse-t,async-io, and an earlier version of this branch built on macOS 26 (arm64). I don't have macFUSE set up, so nothing mounted on macOS.