linux/Documentation/core-api/kernel-api.rst
Linus Torvalds f079ab01b5 Convert xfs/iomap to use folios
This should be all that is needed for XFS to use large folios.
 There is no code in this pull request to create large folios, but
 no additional changes should be needed to XFS or iomap once they
 are created.
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Merge tag 'iomap-5.17' of git://git.infradead.org/users/willy/linux

Pull iomap updates from Matthew Wilcox:
 "Convert xfs/iomap to use folios.

  This should be all that is needed for XFS to use large folios. There
  is no code in this pull request to create large folios, but no
  additional changes should be needed to XFS or iomap once they are
  created.

  Usually this would have come from Darrick, and we had intended that it
  would come that route. Between the holidays and various things which
  Darrick needed to work on, he asked if I could send things directly.

  There weren't any other iomap patches pending for this release, which
  probably also played a role"

* tag 'iomap-5.17' of git://git.infradead.org/users/willy/linux: (26 commits)
  iomap: Inline __iomap_zero_iter into its caller
  xfs: Support large folios
  iomap: Support large folios in invalidatepage
  iomap: Convert iomap_migrate_page() to use folios
  iomap: Convert iomap_add_to_ioend() to take a folio
  iomap: Simplify iomap_do_writepage()
  iomap: Simplify iomap_writepage_map()
  iomap,xfs: Convert ->discard_page to ->discard_folio
  iomap: Convert iomap_write_end_inline to take a folio
  iomap: Convert iomap_write_begin() and iomap_write_end() to folios
  iomap: Convert __iomap_zero_iter to use a folio
  iomap: Allow iomap_write_begin() to be called with the full length
  iomap: Convert iomap_page_mkwrite to use a folio
  iomap: Convert readahead and readpage to use a folio
  iomap: Convert iomap_read_inline_data to take a folio
  iomap: Use folio offsets instead of page offsets
  iomap: Convert bio completions to use folios
  iomap: Pass the iomap_page into iomap_set_range_uptodate
  iomap: Add iomap_invalidate_folio
  iomap: Convert iomap_releasepage to use a folio
  ...
2022-01-12 12:51:41 -08:00

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====================
The Linux Kernel API
====================
List Management Functions
=========================
.. kernel-doc:: include/linux/list.h
:internal:
Basic C Library Functions
=========================
When writing drivers, you cannot in general use routines which are from
the C Library. Some of the functions have been found generally useful
and they are listed below. The behaviour of these functions may vary
slightly from those defined by ANSI, and these deviations are noted in
the text.
String Conversions
------------------
.. kernel-doc:: lib/vsprintf.c
:export:
.. kernel-doc:: include/linux/kstrtox.h
:functions: kstrtol kstrtoul
.. kernel-doc:: lib/kstrtox.c
:export:
.. kernel-doc:: lib/string_helpers.c
:export:
String Manipulation
-------------------
.. kernel-doc:: lib/string.c
:export:
.. kernel-doc:: include/linux/string.h
:internal:
.. kernel-doc:: mm/util.c
:functions: kstrdup kstrdup_const kstrndup kmemdup kmemdup_nul memdup_user
vmemdup_user strndup_user memdup_user_nul
Basic Kernel Library Functions
==============================
The Linux kernel provides more basic utility functions.
Bit Operations
--------------
.. kernel-doc:: include/asm-generic/bitops/instrumented-atomic.h
:internal:
.. kernel-doc:: include/asm-generic/bitops/instrumented-non-atomic.h
:internal:
.. kernel-doc:: include/asm-generic/bitops/instrumented-lock.h
:internal:
Bitmap Operations
-----------------
.. kernel-doc:: lib/bitmap.c
:doc: bitmap introduction
.. kernel-doc:: include/linux/bitmap.h
:doc: declare bitmap
.. kernel-doc:: include/linux/bitmap.h
:doc: bitmap overview
.. kernel-doc:: include/linux/bitmap.h
:doc: bitmap bitops
.. kernel-doc:: lib/bitmap.c
:export:
.. kernel-doc:: lib/bitmap.c
:internal:
.. kernel-doc:: include/linux/bitmap.h
:internal:
Command-line Parsing
--------------------
.. kernel-doc:: lib/cmdline.c
:export:
Sorting
-------
.. kernel-doc:: lib/sort.c
:export:
.. kernel-doc:: lib/list_sort.c
:export:
Text Searching
--------------
.. kernel-doc:: lib/textsearch.c
:doc: ts_intro
.. kernel-doc:: lib/textsearch.c
:export:
.. kernel-doc:: include/linux/textsearch.h
:functions: textsearch_find textsearch_next \
textsearch_get_pattern textsearch_get_pattern_len
CRC and Math Functions in Linux
===============================
CRC Functions
-------------
.. kernel-doc:: lib/crc4.c
:export:
.. kernel-doc:: lib/crc7.c
:export:
.. kernel-doc:: lib/crc8.c
:export:
.. kernel-doc:: lib/crc16.c
:export:
.. kernel-doc:: lib/crc32.c
.. kernel-doc:: lib/crc-ccitt.c
:export:
.. kernel-doc:: lib/crc-itu-t.c
:export:
Base 2 log and power Functions
------------------------------
.. kernel-doc:: include/linux/log2.h
:internal:
Integer power Functions
-----------------------
.. kernel-doc:: lib/math/int_pow.c
:export:
.. kernel-doc:: lib/math/int_sqrt.c
:export:
Division Functions
------------------
.. kernel-doc:: include/asm-generic/div64.h
:functions: do_div
.. kernel-doc:: include/linux/math64.h
:internal:
.. kernel-doc:: lib/math/div64.c
:functions: div_s64_rem div64_u64_rem div64_u64 div64_s64
.. kernel-doc:: lib/math/gcd.c
:export:
UUID/GUID
---------
.. kernel-doc:: lib/uuid.c
:export:
Kernel IPC facilities
=====================
IPC utilities
-------------
.. kernel-doc:: ipc/util.c
:internal:
FIFO Buffer
===========
kfifo interface
---------------
.. kernel-doc:: include/linux/kfifo.h
:internal:
relay interface support
=======================
Relay interface support is designed to provide an efficient mechanism
for tools and facilities to relay large amounts of data from kernel
space to user space.
relay interface
---------------
.. kernel-doc:: kernel/relay.c
:export:
.. kernel-doc:: kernel/relay.c
:internal:
Module Support
==============
Module Loading
--------------
.. kernel-doc:: kernel/kmod.c
:export:
Inter Module support
--------------------
Refer to the file kernel/module.c for more information.
Hardware Interfaces
===================
DMA Channels
------------
.. kernel-doc:: kernel/dma.c
:export:
Resources Management
--------------------
.. kernel-doc:: kernel/resource.c
:internal:
.. kernel-doc:: kernel/resource.c
:export:
MTRR Handling
-------------
.. kernel-doc:: arch/x86/kernel/cpu/mtrr/mtrr.c
:export:
Security Framework
==================
.. kernel-doc:: security/security.c
:internal:
.. kernel-doc:: security/inode.c
:export:
Audit Interfaces
================
.. kernel-doc:: kernel/audit.c
:export:
.. kernel-doc:: kernel/auditsc.c
:internal:
.. kernel-doc:: kernel/auditfilter.c
:internal:
Accounting Framework
====================
.. kernel-doc:: kernel/acct.c
:internal:
Block Devices
=============
.. kernel-doc:: include/linux/bio.h
.. kernel-doc:: block/blk-core.c
:export:
.. kernel-doc:: block/blk-core.c
:internal:
.. kernel-doc:: block/blk-map.c
:export:
.. kernel-doc:: block/blk-sysfs.c
:internal:
.. kernel-doc:: block/blk-settings.c
:export:
.. kernel-doc:: block/blk-flush.c
:export:
.. kernel-doc:: block/blk-lib.c
:export:
.. kernel-doc:: block/blk-integrity.c
:export:
.. kernel-doc:: kernel/trace/blktrace.c
:internal:
.. kernel-doc:: block/genhd.c
:internal:
.. kernel-doc:: block/genhd.c
:export:
.. kernel-doc:: block/bdev.c
:export:
Char devices
============
.. kernel-doc:: fs/char_dev.c
:export:
Clock Framework
===============
The clock framework defines programming interfaces to support software
management of the system clock tree. This framework is widely used with
System-On-Chip (SOC) platforms to support power management and various
devices which may need custom clock rates. Note that these "clocks"
don't relate to timekeeping or real time clocks (RTCs), each of which
have separate frameworks. These :c:type:`struct clk <clk>`
instances may be used to manage for example a 96 MHz signal that is used
to shift bits into and out of peripherals or busses, or otherwise
trigger synchronous state machine transitions in system hardware.
Power management is supported by explicit software clock gating: unused
clocks are disabled, so the system doesn't waste power changing the
state of transistors that aren't in active use. On some systems this may
be backed by hardware clock gating, where clocks are gated without being
disabled in software. Sections of chips that are powered but not clocked
may be able to retain their last state. This low power state is often
called a *retention mode*. This mode still incurs leakage currents,
especially with finer circuit geometries, but for CMOS circuits power is
mostly used by clocked state changes.
Power-aware drivers only enable their clocks when the device they manage
is in active use. Also, system sleep states often differ according to
which clock domains are active: while a "standby" state may allow wakeup
from several active domains, a "mem" (suspend-to-RAM) state may require
a more wholesale shutdown of clocks derived from higher speed PLLs and
oscillators, limiting the number of possible wakeup event sources. A
driver's suspend method may need to be aware of system-specific clock
constraints on the target sleep state.
Some platforms support programmable clock generators. These can be used
by external chips of various kinds, such as other CPUs, multimedia
codecs, and devices with strict requirements for interface clocking.
.. kernel-doc:: include/linux/clk.h
:internal:
Synchronization Primitives
==========================
Read-Copy Update (RCU)
----------------------
.. kernel-doc:: include/linux/rcupdate.h
.. kernel-doc:: kernel/rcu/tree.c
.. kernel-doc:: kernel/rcu/tree_exp.h
.. kernel-doc:: kernel/rcu/update.c
.. kernel-doc:: include/linux/srcu.h
.. kernel-doc:: kernel/rcu/srcutree.c
.. kernel-doc:: include/linux/rculist_bl.h
.. kernel-doc:: include/linux/rculist.h
.. kernel-doc:: include/linux/rculist_nulls.h
.. kernel-doc:: include/linux/rcu_sync.h
.. kernel-doc:: kernel/rcu/sync.c