1. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      
      How this work was done:
      
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      
      Further patches will be generated in subsequent months to fix up cases
      where non-standard license headers were used, and references to license
      had to be inferred by heuristics based on keywords.
      
      The analysis to determine which SPDX License Identifier to be applied to
      a file was done in a spreadsheet of side by side results from of the
      output of two independent scanners (ScanCode & Windriver) producing SPDX
      tag:value files created by Philippe Ombredanne.  Philippe prepared the
      base worksheet, and did an initial spot review of a few 1000 files.
      
      The 4.13 kernel was the starting point of the analysis with 60,537 files
      assessed.  Kate Stewart did a file by file comparison of the scanner
      results in the spreadsheet to determine which SPDX license identifier(s)
      to be applied to the file. She confirmed any determination that was not
      immediately clear with lawyers working with the Linux Foundation.
      
      Criteria used to select files for SPDX license identifier tagging was:
       - Files considered eligible had to be source code files.
       - Make and config files were included as candidates if they contained >5
         lines of source
       - File already had some variant of a license header in it (even if <5
         lines).
      
      All documentation files were explicitly excluded.
      
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
      
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
      
         For non */uapi/* files that summary was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0                                              11139
      
         and resulted in the first patch in this series.
      
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0 WITH Linux-syscall-note                        930
      
         and resulted in the second patch in this series.
      
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|------
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
      
         and that resulted in the third patch in this series.
      
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
      
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
      
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
      
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
      
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: default avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: default avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  2. 09 Sep, 2017 1 commit
    • Sean Purcell's avatar
      squashfs: Add zstd support · 87bf54bb
      Sean Purcell authored
      Add zstd compression and decompression support to SquashFS. zstd is a
      great fit for SquashFS because it can compress at ratios approaching xz,
      while decompressing twice as fast as zlib. For SquashFS in particular,
      it can decompress as fast as lzo and lz4. It also has the flexibility
      to turn down the compression ratio for faster compression times.
      
      The compression benchmark is run on the file tree from the SquashFS archive
      found in ubuntu-16.10-desktop-amd64.iso [1]. It uses `mksquashfs` with the
      default block size (128 KB) and and various compression algorithms/levels.
      xz and zstd are also benchmarked with 256 KB blocks. The decompression
      benchmark times how long it takes to `tar` the file tree into `/dev/null`.
      See the benchmark file in the upstream zstd source repository located under
      `contrib/linux-kernel/squashfs-benchmark.sh` [2] for details.
      
      I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
      The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
      16 GB of RAM, and a SSD.
      
      | Method         | Ratio | Compression MB/s | Decompression MB/s |
      |----------------|-------|------------------|--------------------|
      | gzip           |  2.92 |               15 |                128 |
      | lzo            |  2.64 |              9.5 |                217 |
      | lz4            |  2.12 |               94 |                218 |
      | xz             |  3.43 |              5.5 |                 35 |
      | xz 256 KB      |  3.53 |              5.4 |                 40 |
      | zstd 1         |  2.71 |               96 |                210 |
      | zstd 5         |  2.93 |               69 |                198 |
      | zstd 10        |  3.01 |               41 |                225 |
      | zstd 15        |  3.13 |             11.4 |                224 |
      | zstd 16 256 KB |  3.24 |              8.1 |                210 |
      
      This patch was written by Sean Purcell <me@seanp.xyz>, but I will be
      taking over the submission process.
      
      [1] http://releases.ubuntu.com/16.10/
      [2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/squashfs-benchmark.sh
      
      zstd source repository: https://github.com/facebook/zstdSigned-off-by: default avatarSean Purcell <me@seanp.xyz>
      Signed-off-by: default avatarNick Terrell <terrelln@fb.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Acked-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
      87bf54bb
  3. 27 Nov, 2014 1 commit
  4. 20 Nov, 2013 5 commits
    • Phillip Lougher's avatar
      Squashfs: Directly decompress into the page cache for file data · 0d455c12
      Phillip Lougher authored
      This introduces an implementation of squashfs_readpage_block()
      that directly decompresses into the page cache.
      
      This uses the previously added page handler abstraction to push
      down the necessary kmap_atomic/kunmap_atomic operations on the
      page cache buffers into the decompressors.  This enables
      direct copying into the page cache without using the slow
      kmap/kunmap calls.
      
      The code detects when multiple threads are racing in
      squashfs_readpage() to decompress the same block, and avoids
      this regression by falling back to using an intermediate
      buffer.
      
      This patch enhances the performance of Squashfs significantly
      when multiple processes are accessing the filesystem simultaneously
      because it not only reduces memcopying, but it more importantly
      eliminates the lock contention on the intermediate buffer.
      
      Using single-thread decompression.
      
              dd if=file1 of=/dev/null bs=4096 &
              dd if=file2 of=/dev/null bs=4096 &
              dd if=file3 of=/dev/null bs=4096 &
              dd if=file4 of=/dev/null bs=4096
      
      Before:
      
      629145600 bytes (629 MB) copied, 45.8046 s, 13.7 MB/s
      
      After:
      
      629145600 bytes (629 MB) copied, 9.29414 s, 67.7 MB/s
      Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
      Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
      0d455c12
    • Phillip Lougher's avatar
      Squashfs: Restructure squashfs_readpage() · 5f55dbc0
      Phillip Lougher authored
      Restructure squashfs_readpage() splitting it into separate
      functions for datablocks, fragments and sparse blocks.
      
      Move the memcpying (from squashfs cache entry) implementation of
      squashfs_readpage_block into file_cache.c
      
      This allows different implementations to be supported.
      Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
      Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
      5f55dbc0
    • Phillip Lougher's avatar
      Squashfs: add multi-threaded decompression using percpu variable · d208383d
      Phillip Lougher authored
      Add a multi-threaded decompression implementation which uses
      percpu variables.
      
      Using percpu variables has advantages and disadvantages over
      implementations which do not use percpu variables.
      
      Advantages:
        * the nature of percpu variables ensures decompression is
          load-balanced across the multiple cores.
        * simplicity.
      
      Disadvantages: it limits decompression to one thread per core.
      Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
      d208383d
    • Minchan Kim's avatar
      squashfs: Enhance parallel I/O · cd59c2ec
      Minchan Kim authored
      Now squashfs have used for only one stream buffer for decompression
      so it hurts parallel read performance so this patch supports
      multiple decompressor to enhance performance parallel I/O.
      
      Four 1G file dd read on KVM machine which has 2 CPU and 4G memory.
      
      dd if=test/test1.dat of=/dev/null &
      dd if=test/test2.dat of=/dev/null &
      dd if=test/test3.dat of=/dev/null &
      dd if=test/test4.dat of=/dev/null &
      
      old : 1m39s -> new : 9s
      
      * From v1
        * Change comp_strm with decomp_strm - Phillip
        * Change/add comments - Phillip
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
      cd59c2ec
    • Phillip Lougher's avatar
      Squashfs: Refactor decompressor interface and code · 9508c6b9
      Phillip Lougher authored
      The decompressor interface and code was written from
      the point of view of single-threaded operation.  In doing
      so it mixed a lot of single-threaded implementation specific
      aspects into the decompressor code and elsewhere which makes it
      difficult to seamlessly support multiple different decompressor
      implementations.
      
      This patch does the following:
      
      1.  It removes compressor_options parsing from the decompressor
          init() function.  This allows the decompressor init() function
          to be dynamically called to instantiate multiple decompressors,
          without the compressor options needing to be read and parsed each
          time.
      
      2.  It moves threading and all sleeping operations out of the
          decompressors.  In doing so, it makes the decompressors
          non-blocking wrappers which only deal with interfacing with
          the decompressor implementation.
      
      3. It splits decompressor.[ch] into decompressor generic functions
         in decompressor.[ch], and moves the single threaded
         decompressor implementation into decompressor_single.c.
      
      The result of this patch is Squashfs should now be able to
      support multiple decompressors by adding new decompressor_xxx.c
      files with specialised implementations of the functions in
      decompressor_single.c
      Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
      Reviewed-by: default avatarMinchan Kim <minchan@kernel.org>
      9508c6b9
  5. 22 Jul, 2011 1 commit
  6. 13 Jan, 2011 1 commit
  7. 05 Aug, 2010 1 commit
  8. 31 May, 2010 1 commit
  9. 17 May, 2010 3 commits
  10. 20 Jan, 2010 2 commits
  11. 13 May, 2009 1 commit
  12. 05 Jan, 2009 1 commit