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Ameer Hamza 4ce030e025
Fix snapshot automount race causing duplicate mounts and AVL tree panic
Multiple threads racing to automount the same snapshot can both spawn
mount helper processes that successfully complete, causing both parent
threads to attempt AVL tree registration and triggering a VERIFY()
panic in avl_add(). This occurs because the fsconfig/fsmount API lacks
the serialization provided by traditional mount() via lock_mount().

The fix adds a per-entry mutex (se_mtx) to zfs_snapentry_t that
serializes mount and unmount operations on the same snapshot. The first
mount thread creates a pending entry with se_spa=NULL and holds se_mtx
during the helper execution. Concurrent mounts find the pending entry
and return success without spawning duplicate helpers. Unmount waits on
se_mtx if a mount is pending, ensuring proper serialization. This allows
different snapshots to mount in parallel while preventing the AVL panic.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>
Closes #17943
2025-12-08 13:49:11 -08:00
.github During CI, use nproc instead of sysctl -n hw.ncpu 2025-12-04 16:57:15 -08:00
cmd raidz_test: Restore rand_data protection 2025-12-01 14:34:52 -08:00
config config/kmap_atomic: initialise test data 2025-12-01 10:19:46 -08:00
contrib libuutil: remove packaging 2025-11-17 06:23:17 -08:00
etc docs: fix a few small typos (#17804) 2025-10-01 10:15:46 -07:00
include FreeBSD: Remove HAVE_INLINE_FLSL use 2025-12-02 12:13:16 -08:00
lib Provide loff_t via <fcntl.h> on musl-based Linux systems 2025-12-02 12:14:09 -08:00
man Add knob to disable slow io notifications 2025-11-11 10:42:17 -08:00
module Fix snapshot automount race causing duplicate mounts and AVL tree panic 2025-12-08 13:49:11 -08:00
rpm libuutil: remove packaging 2025-11-17 06:23:17 -08:00
scripts zfs_context: remove duplicate includes 2025-11-12 10:04:03 -08:00
tests ZTS: Add slow_vdev_degraded_sit_out retry 2025-12-04 09:10:22 -08:00
udev zvol_id: make array length properly known at compile time 2025-12-01 10:19:40 -08:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore Packaging: Auto-generate changelog during configure (#15528) 2023-11-16 08:58:47 -08:00
.gitmodules .gitmodules: link to openzfs github repository 2021-04-12 09:37:23 -07:00
.mailmap mailmap/AUTHORS: update with recent new contributors 2025-10-22 09:27:54 -07:00
AUTHORS mailmap/AUTHORS: update with recent new contributors 2025-10-22 09:27:54 -07:00
autogen.sh autogen.sh: remove workaround for automake <1.14, needed for EL <=7 2025-10-30 16:26:56 -07:00
CODE_OF_CONDUCT.md Documentation corrections 2022-12-22 11:34:28 -08:00
configure.ac Linux build: handle CONFIG_OBJTOOL_WERROR=y 2025-06-16 08:12:09 -07:00
copy-builtin copy-builtin: add hooks with sed/>> 2022-05-10 10:17:43 -07:00
COPYRIGHT Fix typos 2020-06-09 21:24:09 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am Install zarcstat and zarcsummary symlinks in Makefile 2025-09-05 10:00:48 -07:00
META Linux 6.17 compat: META 2025-09-26 10:00:18 -07:00
NEWS Fix NEWS file 2020-08-26 21:44:41 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md Fix capitalization typo in README.md 2025-11-03 16:37:58 -08:00
RELEASES.md Update RELEASES.md LTS release to 2.2 2025-01-17 11:04:36 -05:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are any supported branches and releases starting from 13.0-RELEASE.