Linus Torvalds 7696286034 Merge tag 'for-6.19-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
 "Features:

   - shutdown ioctl support (needs CONFIG_BTRFS_EXPERIMENTAL for now):
      - set filesystem state as being shut down (also named going down
        in other filesystems), where all active operations return EIO
        and this cannot be changed until unmount
      - pending operations are attempted to be finished but error
        messages may still show up depending on where exactly the
        shutdown happened

   - scrub (and device replace) vs suspend/hibernate:
      - a running scrub will prevent suspend, which can be annoying as
        suspend is an immediate request and scrub is not critical
      - filesystem freezing before suspend was not sufficient as the
        problem was in process freezing
      - behaviour change: on suspend scrub and device replace are
        cancelled, where scrub can record the last state and continue
        from there; the device replace has to be restarted from the
        beginning

   - zone stats exported in sysfs, from the perspective of the
     filesystem this includes active, reclaimable, relocation etc zones

  Performance:

   - improvements when processing space reservation tickets by
     optimizing locking and shrinking critical sections, cumulative
     improvements in lockstat numbers show +15%

  Notable fixes:

   - use vmalloc fallback when allocating bios as high order allocations
     can happen with wide checksums (like sha256)

   - scrub will always track the last position of progress so it's not
     starting from zero after an error

  Core:

   - under experimental config, checksum calculations are offloaded to
     process context, simplifies locking and allows to remove
     compression write worker kthread(s):
      - speed improvement in direct IO throughput with buffered IO
        fallback is +15% when not offloaded but this is more related to
        internal crypto subsystem improvements
      - this will be probably default in the future removing the sysfs
        tunable

   - (experimental) block size > page size updates:
      - support more operations when not using large folios (encoded
        read/write and send)
      - raid56

   - more preparations for fscrypt support

  Other:

   - more conversions to auto-cleaned variables

   - parameter cleanups and removals

   - extended warning fixes

   - improved printing of structured values like keys

   - lots of other cleanups and refactoring"

* tag 'for-6.19-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (147 commits)
  btrfs: remove unnecessary inode key in btrfs_log_all_parents()
  btrfs: remove redundant zero/NULL initializations in btrfs_alloc_root()
  btrfs: remaining BTRFS_PATH_AUTO_FREE conversions
  btrfs: send: do not allocate memory for xattr data when checking it exists
  btrfs: send: add unlikely to all unexpected overflow checks
  btrfs: reduce arguments to btrfs_del_inode_ref_in_log()
  btrfs: remove root argument from btrfs_del_dir_entries_in_log()
  btrfs: use test_and_set_bit() in btrfs_delayed_delete_inode_ref()
  btrfs: don't search back for dir inode item in INO_LOOKUP_USER
  btrfs: don't rewrite ret from inode_permission
  btrfs: add orig_logical to btrfs_bio for encryption
  btrfs: disable verity on encrypted inodes
  btrfs: disable various operations on encrypted inodes
  btrfs: remove redundant level reset in btrfs_del_items()
  btrfs: simplify leaf traversal after path release in btrfs_next_old_leaf()
  btrfs: optimize balance_level() path reference handling
  btrfs: factor out root promotion logic into promote_child_to_root()
  btrfs: raid56: remove the "_step" infix
  btrfs: raid56: enable bs > ps support
  btrfs: raid56: prepare finish_parity_scrub() to support bs > ps cases
  ...
2025-12-03 20:03:46 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -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
Description
Linux kernel source tree
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