Andreas Hindborg shares Rust 'rnull' block driver patch set

The null block driver is a small driver that accepts all requests and marks them complete quickly, making it useful for benchmarking block-layer implementations. Andreas Hindborg's patch set introduces 'rnull', a Rust implementation of the same functionality. This change brings a Rust-written block driver into the kernel's block layer, allowing testing of Rust code in this subsystem.

Adopting a Rust version carries costs. The existing null_blk driver is already available, so a Rust version adds a parallel implementation that must be maintained. The patch set will need to demonstrate that the Rust driver performs comparably and integrates cleanly with the block layer's existing interfaces.

The rnull driver stops being useful where the null_blk driver is not applicable. It is designed for benchmarking, not for real storage, so it cannot replace actual block devices. Its value is limited to testing the block layer's request handling and the Rust integration itself, not for production workloads.

The patch set was shared in June 2026, indicating it is a proposal for inclusion. The kernel community will need to assess the Rust implementation's compatibility with existing block-layer APIs and whether it meets performance expectations. The outcome will indicate the feasibility of more complex Rust block drivers in the future.