Recent OpenZFS work, by @robn.

(Summary by the AI 🤖, read more about that).

• Current Focus Areas
• Pull requests: Active · Recently completed
• Day journal

Current Focus Areas

• Mounts / dataset mount state — A colleague’s report of bind mount failures after zfs recv -F opened into structural issues with how ZFS manages dataset mount state. Broader work is expanding into mounting infrastructure: mountcache-initial isolates the initial mountcache infrastructure (the /proc/mountinfo parser, dual-tree cache, zfs_is_mounted integration) as a discrete unit being prepared for PR submission. A new libmount branch is reworking ZFS userspace mount management to use Linux’s libmount library, kernel-mount-direct reworks snapshot mounting in zfs_ctldir, and fs-context-uplift is pursuing full init_fs_context mount API adoption.

• Linux kernel support policy — The fs-context adoption work raised a question about the minimum kernel version requirement (currently 4.18/RHEL8-derived): 4.18 was never an LTS kernel, doesn’t compile with modern toolchains, and doesn’t reflect actual support commitments. #18295 proposes removing the version gate in favour of configure checks, with supported distros documented in the README instead.

Pull requests

Active

Recently completed

Gone Cold

Day journal

9 Mar (Monday)

• Linux support — Opened #18295 — remove minimum Linux kernel version requirement; prefer configure checks over a version gate; document actually-supported distros and kernels in README instead
• Mounts — Opened #18296 — libzfs mnttab cleanup; pulls libzfs_mnttab_* functions into libzfs_mnttab.c, general modernisation (SPL mutexes, alloc/free helpers), removes unused legacy struct extmnttab and gettmntany(); preparatory cleanup carried across every mount management prototype, sent separately since it stands on its own
• Mounts — Commented on #18296 in response to @lundman — sketched design direction for mount abstraction: opaque mntent object representing a dataset/mountpoint pair, with OS-specific methods (mount, unmount, property changes, sort); libmount wrapping on Linux, direct implementation on FreeBSD/Windows; libzfs and tools would only ever interact through the abstraction
• Mounts — Started libzfs-mnttab-libmount branch — WIP initial shape of OS-specific mount API, integrating mnttab cleanup changes with the libmount work into a new branch; first cut at the opaque object abstraction described in the design comment
• Reviewed and approved #18290 — FreeBSD: improve dmesg kernel message prefix (concussious); noted Linux mixes ZFS: and zfs: prefixes too, consistency wouldn’t hurt
• Closed #17351 — rename zed binary to zfs-zed; no compelling case made; resolving namespace clashes in a global shared namespace is out of scope

8 Mar (Sunday)

• Linux support — Started linux-no-minimum branch — prompted by fs-context adoption work; investigated minimum kernel version requirement; found 4.18 minimum is RHEL8-derived, no longer compiles with modern toolchains, and doesn’t reflect actual support commitments

7 Mar (Saturday)

• Mounts — Split mountcache-initial branch off mountcache — isolating the initial mountcache infrastructure (the /proc/mountinfo parser, dual-tree cache, zfs_is_mounted integration) as a discrete unit for submission as a PR

6 Mar (Friday)

• Commented on #17000 — design discussion on zfs create -pp syntax for creating parents with canmount=no; suggested -O canmount=no as a general “properties for implicitly-created parents” alternative (intelfx); conceded it was a stretch; behlendorf resolved to proceed with -pp (intelfx)

• #18281 (libzpool: lift zfs_file ops out to separate source file) merged by behlendorf

5 Mar (Thursday)

• SHA-512 / SIMD build — Opened #18285 — separate SIMD compile checks for userspace and kernel toolchains; HAVE_SIMD() selector macro picks the right set at compile time; eliminates Ubuntu 24.04 builder failures where objtool rejects SHA512EXT in the kernel module even though the host compiler supports it

• #18285 (separate SIMD compile checks for userspace and kernel) approved by behlendorf and directly applied

4 Mar (Wednesday)

• SHA-512 / SIMD build — Investigated behlendorf’s report of Ubuntu 24.04 build failure in #18233; diagnosed as toolchain/kernel mismatch: compiler supports SHA512EXT but objtool in the kernel rejects it; responded with intent to fix properly; started simd-config branch — refactoring SIMD feature detection to test against both host and kernel toolchains separately

• Opened #18281 — split zfs_file_* ops out of libzpool/kernel.c into a new libzpool/zfs_file_os.c source file; cleanup requested by @lundman to ease porting work (merged 6 Mar)

• #18259 (more consistent TREE_* macro use in AVL comparators) merged by behlendorf

• #18281 (libzpool: lift zfs_file ops out to separate source file) approved by lundman

3 Mar (Tuesday)

• Mounts — Created libmount branch — WIP: reworking ZFS userspace mount management to use Linux’s libmount library; detect and link libmount, initial mount/unmount through it, mnttab_cache remade as a libmount wrapper, zfs_iter_mounted reimplemented over mtab

• Responded to amotin’s review nits on #18259 — removed unneeded lvb != rvb redundancy (good catch); defended belt-and-suspenders wrapping of zbookmark_compare() (AVL comparators must return -1/0/1, non-AVL functions could break at distance if changed); pushed updated branch

• #18259 (more consistent TREE_* macro use in AVL comparators) reviewed by amotin with nits

2 Mar (Monday)

• Commented on #18259 — responded to amotin’s Clang disassembly feedback; pushed rebase to master with || → | in zfs_refcount_compare to eliminate extra branch (tradeoff: load instead, on same cacheline); noted potential for separate search vs insertion comparator as a future idea

27 Feb (Friday)

• Mounts — Created fs-context-uplift branch — WIP: beginning full init_fs_context mount API adoption, next step following #18260
• Commented on #18259 — posted annotated disassembly showing macro changes produce identical codegen in kernel and userspace builds; noted spa_mapping_key_compare() as another candidate for the same treatment

26 Feb (Thursday)

• #18233 (SHA-512 via Intel SHA512 extension) merged by behlendorf
• #18260 (prefer fs_context mount API when available, groundwork for full init_fs_context adoption) merged by behlendorf

25 Feb (Wednesday)

• Mounts — Continued progress on mountcache branch: built out core mountcache infrastructure — alloc/free, locking (rrwlock), /proc/mountinfo refresh, dual-tree lookup (by dataset and by mountpoint), integrated cache into libzfs_handle_t, wired up zfs_is_mounted to use it; then filtered non-ZFS mount entries out of cache, generalised foreach iterator
• SHA-512 performance — Responded to review comment on #18233 — clarified 0.00 CPB values in sha2_test output when the CPU MHz argument is omitted; not a regression
• SHA-512 performance — Posted performance results on Core Ultra 9 285K VM for #18233: sha512ext at 1.82 CPB vs avx2 at 3.18 CPB (~1.75x faster on Arrow Lake desktop)
• Reviewed and approved #18261 — remove deprecated Fedora 41 from CI (tonyhutter)

24 Feb (Tuesday)

• Linux 7.0 compat — Commented on #18216: confirmed full ZTS pass on 7.0-rc1; maintainer flagged init_fs_context full adoption as a 2.5 goal

• SHA-512 performance — Rebased #18233 to master; shared first real hardware test results (Core Ultra 7 258V, ThinkPad X1 gen 13): sha512ext hashes 1GiB in 205ms vs avx2 at 945ms — ~4.6x faster; in-kernel test to follow

• Opened #18259 — more consistent use of TREE_CMP()/TREE_ISIGN()/TREE_PCMP() macros in AVL comparators; ZTS pass on Linux; notes a few curious constructions worth discussing (merged 4 Mar)

• Linux 7.0 compat — Opened #18260 — prefer new fs_context mount API when available (compiles back to 5.2), inverting the 7.0 compat shim check; sending to CI to verify support range before full init_fs_context adoption (merged 26 Feb)

• #18216 (Linux 7.0 compat: blk_queue_nonrot, posix_acl_to_xattr, legacy mount API removal) merged by behlendorf

• #18233 (SHA-512 via Intel SHA512 extension) approved by tonyhutter

23 Feb (Monday)

• Mounts — Started new mountcache branch — fresh approach to mount caching, starting with an initial /proc/mountinfo parser
• Mounts — Started kernel-mount-direct branch — reworking zfs_ctldir snapshot mounting to hold a vfsmount directly in the snapshot entry rather than going through the automount path
• Started superblock-experiments branch — early WIP: reimagining superblock vs inode relationship

22 Feb (Sunday)

• #18215 (F_SETLEASE compatibility fix) merged
• #18233 (SHA-512 via Intel SHA512 extension) approved by AttilaFueloep; nit about .byte directives in zfs_sha512_transform_sha512ext

20 Feb (Friday)

• #18230 (zdb --key crash fix and test harness improvements) merged by behlendorf
• #18216 (blk_queue_nonrot/posix_acl_to_xattr/legacy mount API changes) approved by behlendorf

19 Feb (Thursday)

• SHA-512 performance — Responded to two review comments on #18233 — fixed bugs in cpuid detection logic caught by reviewer; pushed sha512ext (multiple iterations)

• SHA-512 performance — Fixed $NF awk bug; pushed sha2-test-all-correct (final)

• Mounts — Commented on #18205 — investigated full unmount/remount approach; concluded it needs more work; PR left as safety-check only for now

• Mounts — Created mnttab-cache-highlander branch (WIP: mount table caching)

• #18232 (sha2_test correctness checks for all implementations) merged by behlendorf

• #18216 (Linux 7.0 compat) approved by tonyhutter

18 Feb (Wednesday)

• SHA-512 performance — Created sha512ext and sha2-test-all-correct branches
• SHA-512 performance — Opened #18232 — extend sha2_test correctness checks to all implementations; fix output formatting and get_cpu_freq for variable-frequency CPUs (merged 19 Feb)
• SHA-512 performance — Opened #18233 — icp: SHA-512 via Intel SHA512 extension; tested via Intel SDE with Arrow Lake emulation; requesting community testing on real hardware (merged 26 Feb)
• SHA-512 performance — Pushed sha512ext and sha2-test-all-correct branches (iteration)
• Linux 7.0 compat — Pushed setlease branch; commented on #18215 — addressed review feedback on commit structure
• Mounts — Commented on #18207 — discussed canonical vs. use-time normalisation of mountpoint=; noted cross-OS implications
• SHA-512 performance — Responded to review on #18230 — leftover error-threading code in zdb_derive_key()

17 Feb (Tuesday)

• SHA-512 performance — Created sha512-avx512 branch and pushed — deleted same day (AVX-512 approach abandoned)
• SHA-512 performance — Created zdb-load-key-smarter branch; opened #18230 — fix zdb --key crash on unencrypted datasets; fix test harness to catch silent zdb assertion failures (merged 20 Feb)

16 Feb (Monday)

• Linux 7.0 compat — Pushed setlease branch; responded to review on #18215, fixed commit split
• Code review: #18222, #18133

15 Feb (Sunday)

• Linux 7.0 compat — Created setlease branch; opened #18215 — explicitly set .setlease = generic_setlease to survive removal of kernel fallback in 7.0 (merged 22 Feb)
• Linux 7.0 compat — Pushed linux-7.0-compat branch; opened #18216 — handle blk_queue_nonrot rename, new posix_acl_to_xattr signature, legacy mount API removal
• Code review: #18214

14 Feb (Saturday)

• Linux 7.0 compat — Created linux-7.0-compat branch

13 Feb (Friday)

• Mounts — Commented on #18205 — worked out root cause (outstanding long holds prevent destroy); updated PR description

12 Feb (Thursday)

• Mounts — Created flatten-mount-point branch; opened #18207 — flatten mountpoint= parameter before sort in mountpoint_cmp, fixing mount ordering when trailing slashes present
• Mounts — Commented on #18205 responding to CI failures

11 Feb (Wednesday)

• Linux 6.19 compat — Approved #18197 META update to mark 6.19 support (tonyhutter) — merged; 6.19 work now fully landed
• Mounts — Created no-busy-receive-destroy branch; opened #18205 — abort zfs recv -F with EBUSY when dataset has outstanding bind mounts

9 Feb (Monday)

• Linux 6.19 compat — Confirmed ZTS run passed on 6.19 release day; #18053 effectively complete
• Opened and merged #18189 — AUTHORS update

6 Feb (Friday)

• Code review: #18179, #18180