linux/Documentation/ABI
Linus Torvalds 72ece20127 f2fs update for 6.10-rc1
In this round, we've tried to address some performance issues on zoned storage
 such as direct IO and write_hints. In addition, we've migrated some IO paths
 using folio. Meanwhile, there are multiple bug fixes in the compression paths,
 sanity check conditions, and error handlers.
 
 Enhancement:
  - allow direct io of pinned files for zoned storage
  - assign the write hint per stream by default
  - convert read paths and test_writeback to folio
  - avoid allocating WARM_DATA segment for direct IO
 
 Bug fix:
  - fix false alarm on invalid block address
  - fix to add missing iput() in gc_data_segment()
  - fix to release node block count in error path of f2fs_new_node_page()
  - compress: don't allow unaligned truncation on released compress inode
  - compress: fix to cover {reserve,release}_compress_blocks() w/ cp_rwsem lock
  - compress: fix error path of inc_valid_block_count()
  - compress: fix to update i_compr_blocks correctly
  - fix block migration when section is not aligned to pow2
  - don't trigger OPU on pinfile for direct IO
  - fix to do sanity check on i_xattr_nid in sanity_check_inode()
  - write missing last sum blk of file pinning section
  - clear writeback when compression failed
  - fix to adjust appropirate defragment pg_end
 
 As usual, there are several minor code clean-ups, and fixes to manage missing
 corner cases in the error paths.
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Merge tag 'f2fs-for-6.10.rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs

Pull f2fs updates from Jaegeuk Kim:
 "In this round, we've tried to address some performance issues on zoned
  storage such as direct IO and write_hints. In addition, we've migrated
  some IO paths using folio. Meanwhile, there are multiple bug fixes in
  the compression paths, sanity check conditions, and error handlers.

  Enhancements:
   - allow direct io of pinned files for zoned storage
   - assign the write hint per stream by default
   - convert read paths and test_writeback to folio
   - avoid allocating WARM_DATA segment for direct IO

  Bug fixes:
   - fix false alarm on invalid block address
   - fix to add missing iput() in gc_data_segment()
   - fix to release node block count in error path of
     f2fs_new_node_page()
   - compress:
       - don't allow unaligned truncation on released compress inode
       - cover {reserve,release}_compress_blocks() w/ cp_rwsem lock
       - fix error path of inc_valid_block_count()
       - fix to update i_compr_blocks correctly
   - fix block migration when section is not aligned to pow2
   - don't trigger OPU on pinfile for direct IO
   - fix to do sanity check on i_xattr_nid in sanity_check_inode()
   - write missing last sum blk of file pinning section
   - clear writeback when compression failed
   - fix to adjust appropirate defragment pg_end

  As usual, there are several minor code clean-ups, and fixes to manage
  missing corner cases in the error paths"

* tag 'f2fs-for-6.10.rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (50 commits)
  f2fs: initialize last_block_in_bio variable
  f2fs: Add inline to f2fs_build_fault_attr() stub
  f2fs: fix some ambiguous comments
  f2fs: fix to add missing iput() in gc_data_segment()
  f2fs: allow dirty sections with zero valid block for checkpoint disabled
  f2fs: compress: don't allow unaligned truncation on released compress inode
  f2fs: fix to release node block count in error path of f2fs_new_node_page()
  f2fs: compress: fix to cover {reserve,release}_compress_blocks() w/ cp_rwsem lock
  f2fs: compress: fix error path of inc_valid_block_count()
  f2fs: compress: fix typo in f2fs_reserve_compress_blocks()
  f2fs: compress: fix to update i_compr_blocks correctly
  f2fs: check validation of fault attrs in f2fs_build_fault_attr()
  f2fs: fix to limit gc_pin_file_threshold
  f2fs: remove unused GC_FAILURE_PIN
  f2fs: use f2fs_{err,info}_ratelimited() for cleanup
  f2fs: fix block migration when section is not aligned to pow2
  f2fs: zone: fix to don't trigger OPU on pinfile for direct IO
  f2fs: fix to do sanity check on i_xattr_nid in sanity_check_inode()
  f2fs: fix to avoid allocating WARM_DATA segment for direct IO
  f2fs: remove redundant parameter in is_next_segment_free()
  ...
2024-05-20 13:23:43 -07:00
..
obsolete Documentation: ABI: update sysfs-gpio to reference gpio-cdev 2024-01-22 10:49:03 +01:00
removed Documentation: Mark the 'efivars' sysfs interface as removed 2024-04-13 10:33:02 +02:00
stable EFI updates for v6.10: 2024-05-14 15:19:26 -07:00
testing f2fs update for 6.10-rc1 2024-05-20 13:23:43 -07:00
README

This directory attempts to document the ABI between the Linux kernel and
userspace, and the relative stability of these interfaces.  Due to the
everchanging nature of Linux, and the differing maturity levels, these
interfaces should be used by userspace programs in different ways.

We have four different levels of ABI stability, as shown by the four
different subdirectories in this location.  Interfaces may change levels
of stability according to the rules described below.

The different levels of stability are:

  stable/
	This directory documents the interfaces that the developer has
	defined to be stable.  Userspace programs are free to use these
	interfaces with no restrictions, and backward compatibility for
	them will be guaranteed for at least 2 years.  Most interfaces
	(like syscalls) are expected to never change and always be
	available.

  testing/
	This directory documents interfaces that are felt to be stable,
	as the main development of this interface has been completed.
	The interface can be changed to add new features, but the
	current interface will not break by doing this, unless grave
	errors or security problems are found in them.  Userspace
	programs can start to rely on these interfaces, but they must be
	aware of changes that can occur before these interfaces move to
	be marked stable.  Programs that use these interfaces are
	strongly encouraged to add their name to the description of
	these interfaces, so that the kernel developers can easily
	notify them if any changes occur (see the description of the
	layout of the files below for details on how to do this.)

  obsolete/
	This directory documents interfaces that are still remaining in
	the kernel, but are marked to be removed at some later point in
	time.  The description of the interface will document the reason
	why it is obsolete and when it can be expected to be removed.

  removed/
	This directory contains a list of the old interfaces that have
	been removed from the kernel.

Every file in these directories will contain the following information:

What:		Short description of the interface
Date:		Date created
KernelVersion:	Kernel version this feature first showed up in.
Contact:	Primary contact for this interface (may be a mailing list)
Description:	Long description of the interface and how to use it.
Users:		All users of this interface who wish to be notified when
		it changes.  This is very important for interfaces in
		the "testing" stage, so that kernel developers can work
		with userspace developers to ensure that things do not
		break in ways that are unacceptable.  It is also
		important to get feedback for these interfaces to make
		sure they are working in a proper way and do not need to
		be changed further.


Note:
   The fields should be use a simple notation, compatible with ReST markup.
   Also, the file **should not** have a top-level index, like::

	===
	foo
	===

How things move between levels:

Interfaces in stable may move to obsolete, as long as the proper
notification is given.

Interfaces may be removed from obsolete and the kernel as long as the
documented amount of time has gone by.

Interfaces in the testing state can move to the stable state when the
developers feel they are finished.  They cannot be removed from the
kernel tree without going through the obsolete state first.

It's up to the developer to place their interfaces in the category they
wish for it to start out in.


Notable bits of non-ABI, which should not under any circumstances be considered
stable:

- Kconfig.  Userspace should not rely on the presence or absence of any
  particular Kconfig symbol, in /proc/config.gz, in the copy of .config
  commonly installed to /boot, or in any invocation of the kernel build
  process.

- Kernel-internal symbols.  Do not rely on the presence, absence, location, or
  type of any kernel symbol, either in System.map files or the kernel binary
  itself.  See Documentation/process/stable-api-nonsense.rst.