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Ameer Hamza
88d012a1d6
A deadlock occurs when snapshot expiry tasks are cancelled while holding locks. The snapshot expiry task (snapentry_expire) spawns an umount process and waits for it to complete. Concurrently, ARC memory pressure triggers arc_prune which calls zfs_exit_fs(), attempting to cancel the expiry task while holding locks. The umount process spawned by the expiry task blocks trying to acquire locks held by arc_prune, which is blocked waiting for the expiry task to complete. This creates a circular dependency: expiry task waits for umount, umount waits for arc_prune, arc_prune waits for expiry task. Fix by adding non-blocking cancellation support to taskq_cancel_id(). The zfs_exit_fs() path calls zfsctl_snapshot_unmount_delay() to reschedule the unmount, which needs to cancel any existing expiry task. It now uses non-blocking cancellation to avoid waiting while holding locks, breaking the deadlock by returning immediately when the task is already running. The per-entry se_taskqid_lock has been removed, with all taskqid operations now protected by the global zfs_snapshot_lock held as WRITER. Additionally, an se_in_umount flag prevents recursive waits when zfsctl_destroy() is called during unmount. The taskqid is now only cleared by the caller on successful cancellation; running tasks clear their own taskqid upon completion. Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Ameer Hamza <ahamza@ixsystems.com> Closes #17941
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.
Official Resources
- Documentation - for using and developing this repo
- ZoL site - Linux release info & links
- Mailing lists
- OpenZFS site - for conference videos and info on other platforms (illumos, OSX, Windows, etc)
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
METAfile contains the officially recognized supported Linux kernel versions. - Supported FreeBSD versions are any supported branches and releases starting from 13.0-RELEASE.