Roadmap

The ordering principle is the one a backup and disaster-recovery product needs: correctness and recoverability first, performance last. The UAPI reference tracks go-ublk’s status for every kernel item individually.

Done in v0.2.0#

The October 2026 overhaul (see the changelog) closed what this page used to list as the priorities:

• User recovery: RecoveryReissue/RecoveryQueue/RecoveryFailIO, Detach (with QUIESCE_DEV), Recover, device tags. Tested against SIGKILL and live upgrade handoffs under load.
• Asynchronous backends: a goroutine per request by default, and a raw Handler that can complete from anywhere.
• Full control-plane coverage of the 7.3-rc5 UAPI: every command typed and tested, GET_FEATURES negotiation that refuses rather than silently degrades, unprivileged devices, every parameter block.
• Lifecycle defects #17–#23: the ring leak, STOP_DEV failures, use-after-unmap, silent queue death, unpinned control buffers, the context-cancel wedge, and the restart crash.
• Shared-memory zero copy (SHMEM_ZC, REG_BUF/UNREG_BUF) and larger descriptors (IO_DESC_SIZE).
• Batch I/O (PREP_IO_CMDS, multishot FETCH_IO_CMDS into a provided-buffer ring, batched COMMIT_IO_CMDS).
• Integrity metadata (T10-DIF, IP and NVMe CRC64 protection information, verified end to end by the kernel).
• Zoned devices (host-managed, through a Handler, with zone reports and zone append).
• Zero copy for file-backed devices (REGISTER_IO_BUF, AUTO_BUF_REG): fixed-buffer file I/O on the queue’s ring, no copy through Go memory.
• Per-write FUA, UPDATE_SIZE, errno pass-through, TRY_STOP_DEV, NO_AUTO_PART_SCAN, user copy, NEED_GET_DATA, per-I/O threads, a public GET_DEV_INFO, the shipped systemd units with SIGHUP handling.

Kernel features not yet implemented#

None: as of v0.2.0 go-ublk implements every UBLK_F_* feature, control command, I/O command and parameter block in the 7.3-rc5 UAPI. The one combination not supported is shared-memory zero copy together with file zero copy. The UAPI reference has per-item status.

Testing and releases#

• The kernel and distribution matrix runs the conformance suite under every bootable kernel; results are on the compatibility matrix. Next: run it in CI on every release tag (a workflow with KVM exists and is untested).
• An unprivileged end-to-end test (serving I/O as a non-root user with the udev rules in place).
• A real host power cut, as opposed to a guest reset, in the power-fail test.
• Soak tests over days, and fault injection under memory and GC pressure.
• Longer fuzzing runs of the engine state machine and the UAPI decoders.

Open defects#

Performance#

Only after the above. Candidates: io_uring SQPOLL, measuring and tuning the goroutine-per-request dispatch against Inline and batch I/O.

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