OpenZFS on Linux and FreeBSD
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Robert Evans 0fe0b079a5 dnode_next_offset: backtrack if lower level does not match
This changes the basic search algorithm from a single search up and down
the tree to a full depth-first traversal to handle conditions where the
tree matches at a higher level but not a lower level.

Normally higher level blocks always point to matching blocks, but there
are cases where this does not happen:

1. Racing block pointer updates from dbuf_write_ready.

   Before f664f1ee7f (#8946), both dbuf_write_ready and
   dnode_next_offset held dn_struct_rwlock which protected against
   pointer writes from concurrent syncs.

   This no longer applies, so sync context can f.e. clear or fill all
   L1->L0 BPs before the L2->L1 BP and higher BP's are updated.

   dnode_free_range in particular can reach this case and skip over L1
   blocks that need to be dirtied. Later, sync will panic in
   free_children when trying to clear a non-dirty indirect block.

   This case was found with ztest.

2. txg > 0, non-hole case. This is #11196.

   Freeing blocks/dnodes breaks the assumption that a match at a higher
   level implies a match at a lower level when filtering txg > 0.

   Whenever some but not all L0 blocks are freed, the parent L1 block is
   rewritten. Its updated L2->L1 BP reflects a newer birth txg.

   Later when searching by txg, if the L1 block matches since the txg is
   newer, it is possible that none of the remaining L1->L0 BPs match if
   none have been updated.

   The same behavior is possible with dnode search at L0.

   This is reachable from dsl_destroy_head for synchronous freeing.
   When this happens open context fails to free objects leaving sync
   context stuck freeing potentially many objects.

   This is also reachable from traverse_pool for extreme rewind where it
   is theoretically possible that datasets not dirtied after txg are
   skipped if the MOS has high enough indirection to trigger this case.

In both of these cases, without backtracking the search ends prematurely
as ESRCH result implies no more matches in the entire object.

Signed-off-by: Robert Evans <evansr@google.com>
2024-03-25 10:10:21 -04:00
.github Move nodes into correct subgraphs 2024-01-29 09:16:02 -08:00
cmd Fix option string, adding -e and fixing order 2024-03-21 09:00:29 -07:00
config Linux 6.8 compat: use splice_copy_file_range() for fallback 2024-03-20 16:46:15 -07:00
contrib Packaging: Auto-generate changelog during configure (#15528) 2023-11-16 08:58:47 -08:00
etc Revert "systemd: Use non-absolute paths in Exec* lines" 2023-06-07 11:14:05 -07:00
include ZAP: Some cleanups/micro-optimizations 2024-03-21 16:43:53 -07:00
lib Check for minimum partition size 2024-02-16 09:07:32 -08:00
man zio: update ZIO type x stage documentation 2024-03-21 12:10:04 -07:00
module dnode_next_offset: backtrack if lower level does not match 2024-03-25 10:10:21 -04:00
rpm fix: preserve linux kmod signature in zfs-kmod rpm spec 2024-01-12 12:33:41 -08:00
scripts RAID-Z expansion feature 2023-11-08 10:19:41 -08:00
tests ZTS: Skip cross-fs bclone tests if FreeBSD < 14.0 2024-02-16 08:59:56 -08:00
udev udev: correctly handle partition #16 and later 2024-03-21 16:38:24 -07:00
.cirrus.yml CI: add FreeBSD build with Cirrus CI 2023-10-06 08:50:26 -07:00
.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: initial, trying to tidy up a lot of the commit history 2023-10-10 08:54:30 -07:00
AUTHORS AUTHORS: update with missing names 2023-10-10 08:55:42 -07:00
CODE_OF_CONDUCT.md Documentation corrections 2022-12-22 11:34:28 -08:00
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
META Linux 6.7 compat: META 2024-01-29 11:35:43 -08:00
Makefile.am Process `script` directory for all configs 2022-10-27 16:45:14 -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 FreeBSD: Fix the build on FreeBSD 12 2023-11-27 12:58:03 -08:00
RELEASES.md Add RELEASES.md file 2021-04-02 16:33:40 -07:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
autogen.sh Ubuntu 22.04 integration: ShellCheck 2022-11-18 11:24:48 -08:00
configure.ac Packaging: Auto-generate changelog during configure (#15528) 2023-11-16 08:58:47 -08:00
copy-builtin copy-builtin: add hooks with sed/>> 2022-05-10 10:17:43 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

README.md

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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 12.4-RELEASE.