b3427b18b1
When rolling back a dataset, ZFS has to purge file data resident in the system page cache. To do this, it loops over all vnodes for the mountpoint and calls vn_pages_remove() to purge pages associated with the vnode's VM object. Each page is thus exclusively busied while the dataset's teardown write lock is held. When handling a page fault on a mapped ZFS file, FreeBSD's page fault handler busies newly allocated pages and then uses VOP_GETPAGES to fill them. The ZFS getpages VOP acquires the teardown read lock with vnode pages already busied. This represents a lock order reversal which can lead to deadlock. To break the deadlock, observe that zfs_rezget() need only purge those pages marked valid, and that pages busied by the page fault handler are, by definition, invalid. Furthermore, ZFS pages always transition from invalid to valid with the teardown lock held, and ZFS never creates partially valid pages. Thus, zfs_rezget() can use the new vn_pages_remove_valid() to skip over pages busied by the fault handler. PR: 258208 Tested by: pho Reviewed by: avg, sef, kib MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D32931 Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org> Closes #12828 |
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README.md
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 12.2-RELEASE.