btrfs-uapi: typed Rust wrappers around the btrfs kernel interface

This crate provides typed, safe access to the btrfs kernel interface. Kernel communication uses two mechanisms:

• ioctls for most operations (balance, scrub, subvolume management, ...)
• sysfs under /sys/fs/btrfs/<uuid>/ for status that the kernel does not expose via ioctl (quota state, commit statistics, scrub speed limits)

Safety

All unsafe code is confined to the [raw] module, which contains bindgen-generated types from the kernel UAPI headers (btrfs.h and btrfs_tree.h) and nix ioctl macro declarations for every BTRFS_IOC_* call.

Every other module wraps [raw] into a public API that is entirely safe, exposes no kernel types, and uses idiomatic Rust types throughout: BorrowedFd, Uuid, bitflags, SystemTime, CString, and so on.

Usage

Every function that issues an ioctl takes a [BorrowedFd][std::os::unix::io::BorrowedFd] open on any file within the target btrfs filesystem. Functions in [sysfs] instead take a [uuid::Uuid], which can be obtained from [filesystem::fs_info].

Most ioctl-based operations require CAP_SYS_ADMIN.

Portability

btrfs is Linux-only; this crate does not support other operating systems. Some ioctls used here were introduced in relatively recent kernel versions; this crate targets modern kernels (5.x and later) and does not attempt to detect or work around missing ioctls on older kernels. It is only tested on amd64, but all architectures supported by the kernel (and Rust) should work.