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Qu Wenruo 3adf8f1415 btrfs: do not touch page cache for encoded writes
[BUG]
When running btrfs/284, the following ASSERT() will be triggered with
64K page size and 4K fs block size:

  assertion failed: folio_test_writeback(folio) :: 0, in subpage.c:476
  ------------[ cut here ]------------
  kernel BUG at subpage.c:476!
  Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
  CPU: 4 UID: 0 PID: 2313 Comm: kworker/u37:2 Tainted: G           OE       6.19.0-rc8-custom+ #185 PREEMPT(voluntary)
  Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
  Workqueue: btrfs-endio simple_end_io_work [btrfs]
  pc : btrfs_subpage_clear_writeback+0x148/0x160 [btrfs]
  lr : btrfs_subpage_clear_writeback+0x148/0x160 [btrfs]
  Call trace:
   btrfs_subpage_clear_writeback+0x148/0x160 [btrfs] (P)
   btrfs_folio_clamp_clear_writeback+0xb4/0xd0 [btrfs]
   end_compressed_writeback+0xe0/0x1e0 [btrfs]
   end_bbio_compressed_write+0x1e8/0x218 [btrfs]
   btrfs_bio_end_io+0x108/0x258 [btrfs]
   simple_end_io_work+0x68/0xa8 [btrfs]
   process_one_work+0x168/0x3f0
   worker_thread+0x25c/0x398
   kthread+0x154/0x250
   ret_from_fork+0x10/0x20
  ---[ end trace 0000000000000000 ]---

[CAUSE]
The offending bio is from an encoded write, where the compressed data is
directly written as a data extent, without touching the page cache.

However the encoded write still utilizes the regular buffered write path
for compressed data, by setting the compressed_bio::writeback flag.

When that flag is set, at end_bbio_compressed_write() btrfs will go
clearing the writeback flag of the folios in the page cache.

However for bs < ps cases, the subpage helper has one extra check to make
sure the folio has a writeback flag set in the first place.

But since it's an encoded write, we never go through page
cache, thus the folio has no writeback flag and triggers the ASSERT().

[FIX]
Do not set compressed_bio::writeback flag for encoded writes, and change
the ASSERT() in btrfs_submit_compressed_write() to make sure that flag
is not set.

Fixes: e1bc83f8b1 ("btrfs: get rid of compressed_folios[] usage for encoded writes")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
History 2026-03-17 11:43:07 +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: do not touch page cache for encoded writes 2026-03-17 11:43:07 +01:00
include btrfs: allow mounting filesystems with remap-tree incompat flag 2026-02-03 07:54:35 +01:00
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