linux/fs/f2fs
Linus Torvalds c8c109546a Update to zstd-1.4.10
This PR includes 5 commits that update the zstd library version:
 
 1. Adds a new kernel-style wrapper around zstd. This wrapper API
    is functionally equivalent to the subset of the current zstd API that is
    currently used. The wrapper API changes to be kernel style so that the symbols
    don't collide with zstd's symbols. The update to zstd-1.4.10 maintains the same
    API and preserves the semantics, so that none of the callers need to be
    updated. All callers are updated in the commit, because there are zero
    functional changes.
 2. Adds an indirection for `lib/decompress_unzstd.c` so it
    doesn't depend on the layout of `lib/zstd/` to include every source file.
    This allows the next patch to be automatically generated.
 3. Imports the zstd-1.4.10 source code. This commit is automatically generated
    from upstream zstd (https://github.com/facebook/zstd).
 4. Adds me (terrelln@fb.com) as the maintainer of `lib/zstd`.
 5. Fixes a newly added build warning for clang.
 
 The discussion around this patchset has been pretty long, so I've included a
 FAQ-style summary of the history of the patchset, and why we are taking this
 approach.
 
 Why do we need to update?
 -------------------------
 
 The zstd version in the kernel is based off of zstd-1.3.1, which is was released
 August 20, 2017. Since then zstd has seen many bug fixes and performance
 improvements. And, importantly, upstream zstd is continuously fuzzed by OSS-Fuzz,
 and bug fixes aren't backported to older versions. So the only way to sanely get
 these fixes is to keep up to date with upstream zstd. There are no known security
 issues that affect the kernel, but we need to be able to update in case there
 are. And while there are no known security issues, there are relevant bug fixes.
 For example the problem with large kernel decompression has been fixed upstream
 for over 2 years https://lkml.org/lkml/2020/9/29/27.
 
 Additionally the performance improvements for kernel use cases are significant.
 Measured for x86_64 on my Intel i9-9900k @ 3.6 GHz:
 
 - BtrFS zstd compression at levels 1 and 3 is 5% faster
 - BtrFS zstd decompression+read is 15% faster
 - SquashFS zstd decompression+read is 15% faster
 - F2FS zstd compression+write at level 3 is 8% faster
 - F2FS zstd decompression+read is 20% faster
 - ZRAM decompression+read is 30% faster
 - Kernel zstd decompression is 35% faster
 - Initramfs zstd decompression+build is 5% faster
 
 On top of this, there are significant performance improvements coming down the
 line in the next zstd release, and the new automated update patch generation
 will allow us to pull them easily.
 
 How is the update patch generated?
 ----------------------------------
 
 The first two patches are preparation for updating the zstd version. Then the
 3rd patch in the series imports upstream zstd into the kernel. This patch is
 automatically generated from upstream. A script makes the necessary changes and
 imports it into the kernel. The changes are:
 
 - Replace all libc dependencies with kernel replacements and rewrite includes.
 - Remove unncessary portability macros like: #if defined(_MSC_VER).
 - Use the kernel xxhash instead of bundling it.
 
 This automation gets tested every commit by upstream's continuous integration.
 When we cut a new zstd release, we will submit a patch to the kernel to update
 the zstd version in the kernel.
 
 The automated process makes it easy to keep the kernel version of zstd up to
 date. The current zstd in the kernel shares the guts of the code, but has a lot
 of API and minor changes to work in the kernel. This is because at the time
 upstream zstd was not ready to be used in the kernel envrionment as-is. But,
 since then upstream zstd has evolved to support being used in the kernel as-is.
 
 Why are we updating in one big patch?
 -------------------------------------
 
 The 3rd patch in the series is very large. This is because it is restructuring
 the code, so it both deletes the existing zstd, and re-adds the new structure.
 Future updates will be directly proportional to the changes in upstream zstd
 since the last import. They will admittidly be large, as zstd is an actively
 developed project, and has hundreds of commits between every release. However,
 there is no other great alternative.
 
 One option ruled out is to replay every upstream zstd commit. This is not feasible
 for several reasons:
 - There are over 3500 upstream commits since the zstd version in the kernel.
 - The automation to automatically generate the kernel update was only added recently,
   so older commits cannot easily be imported.
 - Not every upstream zstd commit builds.
 - Only zstd releases are "supported", and individual commits may have bugs that were
   fixed before a release.
 
 Another option to reduce the patch size would be to first reorganize to the new
 file structure, and then apply the patch. However, the current kernel zstd is formatted
 with clang-format to be more "kernel-like". But, the new method imports zstd as-is,
 without additional formatting, to allow for closer correlation with upstream, and
 easier debugging. So the patch wouldn't be any smaller.
 
 It also doesn't make sense to import upstream zstd commit by commit going
 forward. Upstream zstd doesn't support production use cases running of the
 development branch. We have a lot of post-commit fuzzing that catches many bugs,
 so indiviudal commits may be buggy, but fixed before a release. So going forward,
 I intend to import every (important) zstd release into the Kernel.
 
 So, while it isn't ideal, updating in one big patch is the only patch I see forward.
 
 Who is responsible for this code?
 ---------------------------------
 
 I am. This patchset adds me as the maintainer for zstd. Previously, there was no tree
 for zstd patches. Because of that, there were several patches that either got ignored,
 or took a long time to merge, since it wasn't clear which tree should pick them up.
 I'm officially stepping up as maintainer, and setting up my tree as the path through
 which zstd patches get merged. I'll make sure that patches to the kernel zstd get
 ported upstream, so they aren't erased when the next version update happens.
 
 How is this code tested?
 ------------------------
 
 I tested every caller of zstd on x86_64 (BtrFS, ZRAM, SquashFS, F2FS, Kernel,
 InitRAMFS). I also tested Kernel & InitRAMFS on i386 and aarch64. I checked both
 performance and correctness.
 
 Also, thanks to many people in the community who have tested these patches locally.
 If you have tested the patches, please reply with a Tested-By so I can collect them
 for the PR I will send to Linus.
 
 Lastly, this code will bake in linux-next before being merged into v5.16.
 
 Why update to zstd-1.4.10 when zstd-1.5.0 has been released?
 ------------------------------------------------------------
 
 This patchset has been outstanding since 2020, and zstd-1.4.10 was the latest
 release when it was created. Since the update patch is automatically generated
 from upstream, I could generate it from zstd-1.5.0. However, there were some
 large stack usage regressions in zstd-1.5.0, and are only fixed in the latest
 development branch. And the latest development branch contains some new code that
 needs to bake in the fuzzer before I would feel comfortable releasing to the
 kernel.
 
 Once this patchset has been merged, and we've released zstd-1.5.1, we can update
 the kernel to zstd-1.5.1, and exercise the update process.
 
 You may notice that zstd-1.4.10 doesn't exist upstream. This release is an
 artifical release based off of zstd-1.4.9, with some fixes for the kernel
 backported from the development branch. I will tag the zstd-1.4.10 release after
 this patchset is merged, so the Linux Kernel is running a known version of zstd
 that can be debugged upstream.
 
 Why was a wrapper API added?
 ----------------------------
 
 The first versions of this patchset migrated the kernel to the upstream zstd
 API. It first added a shim API that supported the new upstream API with the old
 code, then updated callers to use the new shim API, then transitioned to the
 new code and deleted the shim API. However, Cristoph Hellwig suggested that we
 transition to a kernel style API, and hide zstd's upstream API behind that.
 This is because zstd's upstream API is supports many other use cases, and does
 not follow the kernel style guide, while the kernel API is focused on the
 kernel's use cases, and follows the kernel style guide.
 
 Where is the previous discussion?
 ---------------------------------
 
 Links for the discussions of the previous versions of the patch set.
 The largest changes in the design of the patchset are driven by the discussions
 in V11, V5, and V1. Sorry for the mix of links, I couldn't find most of the the
 threads on lkml.org.
 
 V12: https://www.spinics.net/lists/linux-crypto/msg58189.html
 V11: https://lore.kernel.org/linux-btrfs/20210430013157.747152-1-nickrterrell@gmail.com/
 V10: https://lore.kernel.org/lkml/20210426234621.870684-2-nickrterrell@gmail.com/
 V9: https://lore.kernel.org/linux-btrfs/20210330225112.496213-1-nickrterrell@gmail.com/
 V8: https://lore.kernel.org/linux-f2fs-devel/20210326191859.1542272-1-nickrterrell@gmail.com/
 V7: https://lkml.org/lkml/2020/12/3/1195
 V6: https://lkml.org/lkml/2020/12/2/1245
 V5: https://lore.kernel.org/linux-btrfs/20200916034307.2092020-1-nickrterrell@gmail.com/
 V4: https://www.spinics.net/lists/linux-btrfs/msg105783.html
 V3: https://lkml.org/lkml/2020/9/23/1074
 V2: https://www.spinics.net/lists/linux-btrfs/msg105505.html
 V1: https://lore.kernel.org/linux-btrfs/20200916034307.2092020-1-nickrterrell@gmail.com/
 
 Signed-off-by: Nick Terrell <terrelln@fb.com>
 Tested By: Paul Jones <paul@pauljones.id.au>
 Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
 Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 on x86-64
 Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
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Merge tag 'zstd-for-linus-v5.16' of git://github.com/terrelln/linux

Pull zstd update from Nick Terrell:
 "Update to zstd-1.4.10.

  Add myself as the maintainer of zstd and update the zstd version in
  the kernel, which is now 4 years out of date, to a much more recent
  zstd release. This includes bug fixes, much more extensive fuzzing,
  and performance improvements. And generates the kernel zstd
  automatically from upstream zstd, so it is easier to keep the zstd
  verison up to date, and we don't fall so far out of date again.

  This includes 5 commits that update the zstd library version:

   - Adds a new kernel-style wrapper around zstd.

     This wrapper API is functionally equivalent to the subset of the
     current zstd API that is currently used. The wrapper API changes to
     be kernel style so that the symbols don't collide with zstd's
     symbols. The update to zstd-1.4.10 maintains the same API and
     preserves the semantics, so that none of the callers need to be
     updated. All callers are updated in the commit, because there are
     zero functional changes.

   - Adds an indirection for `lib/decompress_unzstd.c` so it doesn't
     depend on the layout of `lib/zstd/` to include every source file.
     This allows the next patch to be automatically generated.

   - Imports the zstd-1.4.10 source code. This commit is automatically
     generated from upstream zstd (https://github.com/facebook/zstd).

   - Adds me (terrelln@fb.com) as the maintainer of `lib/zstd`.

   - Fixes a newly added build warning for clang.

  The discussion around this patchset has been pretty long, so I've
  included a FAQ-style summary of the history of the patchset, and why
  we are taking this approach.

  Why do we need to update?
  -------------------------

  The zstd version in the kernel is based off of zstd-1.3.1, which is
  was released August 20, 2017. Since then zstd has seen many bug fixes
  and performance improvements. And, importantly, upstream zstd is
  continuously fuzzed by OSS-Fuzz, and bug fixes aren't backported to
  older versions. So the only way to sanely get these fixes is to keep
  up to date with upstream zstd.

  There are no known security issues that affect the kernel, but we need
  to be able to update in case there are. And while there are no known
  security issues, there are relevant bug fixes. For example the problem
  with large kernel decompression has been fixed upstream for over 2
  years [1]

  Additionally the performance improvements for kernel use cases are
  significant. Measured for x86_64 on my Intel i9-9900k @ 3.6 GHz:

   - BtrFS zstd compression at levels 1 and 3 is 5% faster

   - BtrFS zstd decompression+read is 15% faster

   - SquashFS zstd decompression+read is 15% faster

   - F2FS zstd compression+write at level 3 is 8% faster

   - F2FS zstd decompression+read is 20% faster

   - ZRAM decompression+read is 30% faster

   - Kernel zstd decompression is 35% faster

   - Initramfs zstd decompression+build is 5% faster

  On top of this, there are significant performance improvements coming
  down the line in the next zstd release, and the new automated update
  patch generation will allow us to pull them easily.

  How is the update patch generated?
  ----------------------------------

  The first two patches are preparation for updating the zstd version.
  Then the 3rd patch in the series imports upstream zstd into the
  kernel. This patch is automatically generated from upstream. A script
  makes the necessary changes and imports it into the kernel. The
  changes are:

   - Replace all libc dependencies with kernel replacements and rewrite
     includes.

   - Remove unncessary portability macros like: #if defined(_MSC_VER).

   - Use the kernel xxhash instead of bundling it.

  This automation gets tested every commit by upstream's continuous
  integration. When we cut a new zstd release, we will submit a patch to
  the kernel to update the zstd version in the kernel.

  The automated process makes it easy to keep the kernel version of zstd
  up to date. The current zstd in the kernel shares the guts of the
  code, but has a lot of API and minor changes to work in the kernel.
  This is because at the time upstream zstd was not ready to be used in
  the kernel envrionment as-is. But, since then upstream zstd has
  evolved to support being used in the kernel as-is.

  Why are we updating in one big patch?
  -------------------------------------

  The 3rd patch in the series is very large. This is because it is
  restructuring the code, so it both deletes the existing zstd, and
  re-adds the new structure. Future updates will be directly
  proportional to the changes in upstream zstd since the last import.
  They will admittidly be large, as zstd is an actively developed
  project, and has hundreds of commits between every release. However,
  there is no other great alternative.

  One option ruled out is to replay every upstream zstd commit. This is
  not feasible for several reasons:

   - There are over 3500 upstream commits since the zstd version in the
     kernel.

   - The automation to automatically generate the kernel update was only
     added recently, so older commits cannot easily be imported.

   - Not every upstream zstd commit builds.

   - Only zstd releases are "supported", and individual commits may have
     bugs that were fixed before a release.

  Another option to reduce the patch size would be to first reorganize
  to the new file structure, and then apply the patch. However, the
  current kernel zstd is formatted with clang-format to be more
  "kernel-like". But, the new method imports zstd as-is, without
  additional formatting, to allow for closer correlation with upstream,
  and easier debugging. So the patch wouldn't be any smaller.

  It also doesn't make sense to import upstream zstd commit by commit
  going forward. Upstream zstd doesn't support production use cases
  running of the development branch. We have a lot of post-commit
  fuzzing that catches many bugs, so indiviudal commits may be buggy,
  but fixed before a release. So going forward, I intend to import every
  (important) zstd release into the Kernel.

  So, while it isn't ideal, updating in one big patch is the only patch
  I see forward.

  Who is responsible for this code?
  ---------------------------------

  I am. This patchset adds me as the maintainer for zstd. Previously,
  there was no tree for zstd patches. Because of that, there were
  several patches that either got ignored, or took a long time to merge,
  since it wasn't clear which tree should pick them up. I'm officially
  stepping up as maintainer, and setting up my tree as the path through
  which zstd patches get merged. I'll make sure that patches to the
  kernel zstd get ported upstream, so they aren't erased when the next
  version update happens.

  How is this code tested?
  ------------------------

  I tested every caller of zstd on x86_64 (BtrFS, ZRAM, SquashFS, F2FS,
  Kernel, InitRAMFS). I also tested Kernel & InitRAMFS on i386 and
  aarch64. I checked both performance and correctness.

  Also, thanks to many people in the community who have tested these
  patches locally.

  Lastly, this code will bake in linux-next before being merged into
  v5.16.

  Why update to zstd-1.4.10 when zstd-1.5.0 has been released?
  ------------------------------------------------------------

  This patchset has been outstanding since 2020, and zstd-1.4.10 was the
  latest release when it was created. Since the update patch is
  automatically generated from upstream, I could generate it from
  zstd-1.5.0.

  However, there were some large stack usage regressions in zstd-1.5.0,
  and are only fixed in the latest development branch. And the latest
  development branch contains some new code that needs to bake in the
  fuzzer before I would feel comfortable releasing to the kernel.

  Once this patchset has been merged, and we've released zstd-1.5.1, we
  can update the kernel to zstd-1.5.1, and exercise the update process.

  You may notice that zstd-1.4.10 doesn't exist upstream. This release
  is an artifical release based off of zstd-1.4.9, with some fixes for
  the kernel backported from the development branch. I will tag the
  zstd-1.4.10 release after this patchset is merged, so the Linux Kernel
  is running a known version of zstd that can be debugged upstream.

  Why was a wrapper API added?
  ----------------------------

  The first versions of this patchset migrated the kernel to the
  upstream zstd API. It first added a shim API that supported the new
  upstream API with the old code, then updated callers to use the new
  shim API, then transitioned to the new code and deleted the shim API.
  However, Cristoph Hellwig suggested that we transition to a kernel
  style API, and hide zstd's upstream API behind that. This is because
  zstd's upstream API is supports many other use cases, and does not
  follow the kernel style guide, while the kernel API is focused on the
  kernel's use cases, and follows the kernel style guide.

  Where is the previous discussion?
  ---------------------------------

  Links for the discussions of the previous versions of the patch set
  below. The largest changes in the design of the patchset are driven by
  the discussions in v11, v5, and v1. Sorry for the mix of links, I
  couldn't find most of the the threads on lkml.org"

Link: https://lkml.org/lkml/2020/9/29/27 [1]
Link: https://www.spinics.net/lists/linux-crypto/msg58189.html [v12]
Link: https://lore.kernel.org/linux-btrfs/20210430013157.747152-1-nickrterrell@gmail.com/ [v11]
Link: https://lore.kernel.org/lkml/20210426234621.870684-2-nickrterrell@gmail.com/ [v10]
Link: https://lore.kernel.org/linux-btrfs/20210330225112.496213-1-nickrterrell@gmail.com/ [v9]
Link: https://lore.kernel.org/linux-f2fs-devel/20210326191859.1542272-1-nickrterrell@gmail.com/ [v8]
Link: https://lkml.org/lkml/2020/12/3/1195 [v7]
Link: https://lkml.org/lkml/2020/12/2/1245 [v6]
Link: https://lore.kernel.org/linux-btrfs/20200916034307.2092020-1-nickrterrell@gmail.com/ [v5]
Link: https://www.spinics.net/lists/linux-btrfs/msg105783.html [v4]
Link: https://lkml.org/lkml/2020/9/23/1074 [v3]
Link: https://www.spinics.net/lists/linux-btrfs/msg105505.html [v2]
Link: https://lore.kernel.org/linux-btrfs/20200916034307.2092020-1-nickrterrell@gmail.com/ [v1]
Signed-off-by: Nick Terrell <terrelln@fb.com>
Tested By: Paul Jones <paul@pauljones.id.au>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 on x86-64
Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>

* tag 'zstd-for-linus-v5.16' of git://github.com/terrelln/linux:
  lib: zstd: Add cast to silence clang's -Wbitwise-instead-of-logical
  MAINTAINERS: Add maintainer entry for zstd
  lib: zstd: Upgrade to latest upstream zstd version 1.4.10
  lib: zstd: Add decompress_sources.h for decompress_unzstd
  lib: zstd: Add kernel-specific API
2021-11-13 15:32:30 -08:00
..
acl.c vfs: add rcu argument to ->get_acl() callback 2021-08-18 22:08:24 +02:00
acl.h vfs: add rcu argument to ->get_acl() callback 2021-08-18 22:08:24 +02:00
checkpoint.c f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
compress.c Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
data.c f2fs: invalidate META_MAPPING before IPU/DIO write 2021-11-09 08:16:34 -08:00
debug.c f2fs: convert S_IRUGO to 0444 2021-08-17 11:59:05 -07:00
dir.c f2fs: support fault injection for f2fs_kmem_cache_alloc() 2021-08-17 11:59:05 -07:00
extent_cache.c f2fs: support fault injection for f2fs_kmem_cache_alloc() 2021-08-17 11:59:05 -07:00
f2fs.h f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
file.c f2fs-for-5.16-rc1 2021-11-13 11:20:22 -08:00
gc.c f2fs: introduce fragment allocation mode mount option 2021-10-26 14:04:30 -07:00
gc.h f2fs: introduce gc_merge mount option 2021-03-30 18:48:56 -07:00
hash.c f2fs: Handle casefolding with Encryption 2020-12-02 22:00:21 -08:00
inline.c f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
inode.c f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
iostat.c f2fs: introduce periodic iostat io latency traces 2021-08-23 10:25:51 -07:00
iostat.h f2fs: introduce periodic iostat io latency traces 2021-08-23 10:25:51 -07:00
Kconfig f2fs: separate out iostat feature 2021-08-23 10:25:51 -07:00
Makefile f2fs: separate out iostat feature 2021-08-23 10:25:51 -07:00
namei.c f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
node.c f2fs: set SBI_NEED_FSCK flag when inconsistent node block found 2021-09-20 16:29:00 -07:00
node.h f2fs: introduce excess_dirty_threshold() 2021-09-20 16:12:51 -07:00
recovery.c f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
segment.c f2fs: invalidate META_MAPPING before IPU/DIO write 2021-11-09 08:16:34 -08:00
segment.h f2fs: introduce fragment allocation mode mount option 2021-10-26 14:04:30 -07:00
shrinker.c f2fs: avoid race condition for shrinker count 2020-12-03 00:59:26 -08:00
super.c Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
sysfs.c f2fs: introduce fragment allocation mode mount option 2021-10-26 14:04:30 -07:00
verity.c f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
xattr.c f2fs: support fault injection for dquot_initialize() 2021-10-29 10:38:53 -07:00
xattr.h f2fs: code cleanup by removing ifdef macro surrounding 2020-05-26 18:56:10 -07:00