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Qu Wenruo d1a020a8d7 btrfs: add mount time auto fix for orphan fst entries
[BUG]
Before btrfs-progs v6.16.1 release, mkfs.btrfs can leave free space tree
entries for deleted chunks:

  # mkfs.btrfs -f -O fst $dev
  # btrfs ins dump-tree -t chunk $dev
  btrfs-progs v6.16
  chunk tree
  leaf 22036480 items 4 free space 15781 generation 8 owner CHUNK_TREE
  leaf 22036480 flags 0x1(WRITTEN) backref revision 1
	 item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 16185 itemsize 98
	 item 1 key (FIRST_CHUNK_TREE CHUNK_ITEM 13631488) itemoff 16105 itemsize 80
	 ^^^ The first chunk is at 13631488
	 item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 22020096) itemoff 15993 itemsize 112
	 item 3 key (FIRST_CHUNK_TREE CHUNK_ITEM 30408704) itemoff 15881 itemsize 112

  # btrfs ins dump-tree -t free-space-tree $dev
  btrfs-progs v6.16
  free space tree key (FREE_SPACE_TREE ROOT_ITEM 0)
  leaf 30556160 items 13 free space 15918 generation 8 owner FREE_SPACE_TREE
  leaf 30556160 flags 0x1(WRITTEN) backref revision 1
	 item 0 key (1048576 FREE_SPACE_INFO 4194304) itemoff 16275 itemsize 8
		 free space info extent count 1 flags 0
	 item 1 key (1048576 FREE_SPACE_EXTENT 4194304) itemoff 16275 itemsize 0
		 free space extent
	 item 2 key (5242880 FREE_SPACE_INFO 8388608) itemoff 16267 itemsize 8
		 free space info extent count 1 flags 0
	 item 3 key (5242880 FREE_SPACE_EXTENT 8388608) itemoff 16267 itemsize 0
		 free space extent
	 ^^^ Above 4 items are all before the first chunk.
	 item 4 key (13631488 FREE_SPACE_INFO 8388608) itemoff 16259 itemsize 8
		 free space info extent count 1 flags 0
	 item 5 key (13631488 FREE_SPACE_EXTENT 8388608) itemoff 16259 itemsize 0
		 free space extent
	 ...

This can trigger btrfs check errors.

[CAUSE]
It's a bug in free space tree implementation of btrfs-progs, which
doesn't delete involved fst entries for the to-be-deleted chunk/block
group.

[ENHANCEMENT]
The mostly common fix is to clear the space cache and rebuild it, but
that requires a ro->rw remount which may not be possible for rootfs,
and also relies on users to use "clear_cache" mount option manually.

Here introduce a kernel fix for it, which will delete any entries that
is before the first block group automatically at the first RW mount.

For filesystems without such problem, the overhead is just a single tree
search and no modification to the free space tree, thus the overhead
should be minimal.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
History 2026-02-03 07:51:34 +01:00
arch RISC-V updates for v6.19-rc8 2026-01-30 16:57:36 -08:00
block block-6.19-20260122 2026-01-23 12:53:56 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: authencesn - reject too-short AAD (assoclen<8) to match ESP/ESN spec 2026-01-20 14:38:48 +08:00
Documentation sound fixes for 6.19-rc8 2026-01-31 08:52:41 -08:00
drivers SCSI fixes on 20260201 2026-02-01 11:24:53 -08:00
fs btrfs: add mount time auto fix for orphan fst entries 2026-02-03 07:51:34 +01:00
include Fix a race in the user-callchains code. 2026-02-01 10:47:21 -08:00
init Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
io_uring io_uring-6.19-20260122 2026-01-23 12:51:00 -08:00
ipc Significant patch series in this pull request: 2025-12-06 14:01:20 -08:00
kernel Fix a race in the user-callchains code. 2026-02-01 10:47:21 -08:00
lib mm/zone_device: reinitialize large zone device private folios 2026-01-26 19:03:48 -08:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm 16 hotfixes. 9 are cc:stable, 12 are for MM. 2026-01-29 11:09:13 -08:00
net net: fix segmentation of forwarding fraglist GRO 2026-01-29 14:40:12 +01:00
rust Rust fixes for v6.19 2026-01-30 16:15:59 -08:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2025-12-31 15:19:25 +08:00
scripts Miscellaneous objtool fixes: 2026-02-01 10:27:43 -08:00
security keys/trusted_keys: fix handle passed to tpm_buf_append_name during unseal 2026-01-25 19:03:45 +02:00
sound ASoC: Fixes for v6.19 2026-01-29 13:58:06 +01:00
tools Miscellaneous objtool fixes: 2026-02-01 10:27:43 -08:00
usr initramfs: add gen_init_cpio to hostprogs unconditionally 2025-11-26 21:55:40 +01:00
virt KVM fixes for 6.19-rc1 2025-12-18 18:38:45 +01:00
.clang-format s390/pci: Fix cyclic dead-lock in zpci_zdev_put() and zpci_scan_devices() 2025-12-14 11:03:58 +01:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap 16 hotfixes. 9 are cc:stable, 12 are for MM. 2026-01-29 11:09:13 -08:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS nfc: MAINTAINERS: Orphan the NFC and look for new maintainers 2026-01-20 16:05:38 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Including fixes from bluetooth, CAN and wireless. 2026-01-29 10:21:52 -08:00
Makefile Linux 6.19-rc8 2026-02-01 14:01:13 -08:00
README README: restructure with role-based documentation and guidelines 2025-11-29 08:40:33 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst



Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst