1. 06 Nov, 2018 1 commit
  2. 03 Nov, 2018 4 commits
  3. 04 Sep, 2018 2 commits
  4. 12 Jun, 2018 1 commit
    • Kees Cook's avatar
      treewide: kmalloc() -> kmalloc_array() · 6da2ec56
      Kees Cook authored
      
      
      The kmalloc() function has a 2-factor argument form, kmalloc_array(). This
      patch replaces cases of:
      
              kmalloc(a * b, gfp)
      
      with:
              kmalloc_array(a * b, gfp)
      
      as well as handling cases of:
      
              kmalloc(a * b * c, gfp)
      
      with:
      
              kmalloc(array3_size(a, b, c), gfp)
      
      as it's slightly less ugly than:
      
              kmalloc_array(array_size(a, b), c, gfp)
      
      This does, however, attempt to ignore constant size factors like:
      
              kmalloc(4 * 1024, gfp)
      
      though any constants defined via macros get caught up in the conversion.
      
      Any factors with a sizeof() of "unsigned char", "char", and "u8" were
      dropped, since they're redundant.
      
      The tools/ directory was manually excluded, since it has its own
      implementation of kmalloc().
      
      The Coccinelle script used for this was:
      
      // Fix redundant parens around sizeof().
      @@
      type TYPE;
      expression THING, E;
      @@
      
      (
        kmalloc(
      -	(sizeof(TYPE)) * E
      +	sizeof(TYPE) * E
        , ...)
      |
        kmalloc(
      -	(sizeof(THING)) * E
      +	sizeof(THING) * E
        , ...)
      )
      
      // Drop single-byte sizes and redundant parens.
      @@
      expression COUNT;
      typedef u8;
      typedef __u8;
      @@
      
      (
        kmalloc(
      -	sizeof(u8) * (COUNT)
      +	COUNT
        , ...)
      |
        kmalloc(
      -	sizeof(__u8) * (COUNT)
      +	COUNT
        , ...)
      |
        kmalloc(
      -	sizeof(char) * (COUNT)
      +	COUNT
        , ...)
      |
        kmalloc(
      -	sizeof(unsigned char) * (COUNT)
      +	COUNT
        , ...)
      |
        kmalloc(
      -	sizeof(u8) * COUNT
      +	COUNT
        , ...)
      |
        kmalloc(
      -	sizeof(__u8) * COUNT
      +	COUNT
        , ...)
      |
        kmalloc(
      -	sizeof(char) * COUNT
      +	COUNT
        , ...)
      |
        kmalloc(
      -	sizeof(unsigned char) * COUNT
      +	COUNT
        , ...)
      )
      
      // 2-factor product with sizeof(type/expression) and identifier or constant.
      @@
      type TYPE;
      expression THING;
      identifier COUNT_ID;
      constant COUNT_CONST;
      @@
      
      (
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(TYPE) * (COUNT_ID)
      +	COUNT_ID, sizeof(TYPE)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(TYPE) * COUNT_ID
      +	COUNT_ID, sizeof(TYPE)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(TYPE) * (COUNT_CONST)
      +	COUNT_CONST, sizeof(TYPE)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(TYPE) * COUNT_CONST
      +	COUNT_CONST, sizeof(TYPE)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(THING) * (COUNT_ID)
      +	COUNT_ID, sizeof(THING)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(THING) * COUNT_ID
      +	COUNT_ID, sizeof(THING)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(THING) * (COUNT_CONST)
      +	COUNT_CONST, sizeof(THING)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(THING) * COUNT_CONST
      +	COUNT_CONST, sizeof(THING)
        , ...)
      )
      
      // 2-factor product, only identifiers.
      @@
      identifier SIZE, COUNT;
      @@
      
      - kmalloc
      + kmalloc_array
        (
      -	SIZE * COUNT
      +	COUNT, SIZE
        , ...)
      
      // 3-factor product with 1 sizeof(type) or sizeof(expression), with
      // redundant parens removed.
      @@
      expression THING;
      identifier STRIDE, COUNT;
      type TYPE;
      @@
      
      (
        kmalloc(
      -	sizeof(TYPE) * (COUNT) * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kmalloc(
      -	sizeof(TYPE) * (COUNT) * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kmalloc(
      -	sizeof(TYPE) * COUNT * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kmalloc(
      -	sizeof(TYPE) * COUNT * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(TYPE))
        , ...)
      |
        kmalloc(
      -	sizeof(THING) * (COUNT) * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      |
        kmalloc(
      -	sizeof(THING) * (COUNT) * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      |
        kmalloc(
      -	sizeof(THING) * COUNT * (STRIDE)
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      |
        kmalloc(
      -	sizeof(THING) * COUNT * STRIDE
      +	array3_size(COUNT, STRIDE, sizeof(THING))
        , ...)
      )
      
      // 3-factor product with 2 sizeof(variable), with redundant parens removed.
      @@
      expression THING1, THING2;
      identifier COUNT;
      type TYPE1, TYPE2;
      @@
      
      (
        kmalloc(
      -	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
        , ...)
      |
        kmalloc(
      -	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
        , ...)
      |
        kmalloc(
      -	sizeof(THING1) * sizeof(THING2) * COUNT
      +	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
        , ...)
      |
        kmalloc(
      -	sizeof(THING1) * sizeof(THING2) * (COUNT)
      +	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
        , ...)
      |
        kmalloc(
      -	sizeof(TYPE1) * sizeof(THING2) * COUNT
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
        , ...)
      |
        kmalloc(
      -	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
      +	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
        , ...)
      )
      
      // 3-factor product, only identifiers, with redundant parens removed.
      @@
      identifier STRIDE, SIZE, COUNT;
      @@
      
      (
        kmalloc(
      -	(COUNT) * STRIDE * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kmalloc(
      -	COUNT * (STRIDE) * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kmalloc(
      -	COUNT * STRIDE * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kmalloc(
      -	(COUNT) * (STRIDE) * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kmalloc(
      -	COUNT * (STRIDE) * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kmalloc(
      -	(COUNT) * STRIDE * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kmalloc(
      -	(COUNT) * (STRIDE) * (SIZE)
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      |
        kmalloc(
      -	COUNT * STRIDE * SIZE
      +	array3_size(COUNT, STRIDE, SIZE)
        , ...)
      )
      
      // Any remaining multi-factor products, first at least 3-factor products,
      // when they're not all constants...
      @@
      expression E1, E2, E3;
      constant C1, C2, C3;
      @@
      
      (
        kmalloc(C1 * C2 * C3, ...)
      |
        kmalloc(
      -	(E1) * E2 * E3
      +	array3_size(E1, E2, E3)
        , ...)
      |
        kmalloc(
      -	(E1) * (E2) * E3
      +	array3_size(E1, E2, E3)
        , ...)
      |
        kmalloc(
      -	(E1) * (E2) * (E3)
      +	array3_size(E1, E2, E3)
        , ...)
      |
        kmalloc(
      -	E1 * E2 * E3
      +	array3_size(E1, E2, E3)
        , ...)
      )
      
      // And then all remaining 2 factors products when they're not all constants,
      // keeping sizeof() as the second factor argument.
      @@
      expression THING, E1, E2;
      type TYPE;
      constant C1, C2, C3;
      @@
      
      (
        kmalloc(sizeof(THING) * C2, ...)
      |
        kmalloc(sizeof(TYPE) * C2, ...)
      |
        kmalloc(C1 * C2 * C3, ...)
      |
        kmalloc(C1 * C2, ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(TYPE) * (E2)
      +	E2, sizeof(TYPE)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(TYPE) * E2
      +	E2, sizeof(TYPE)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(THING) * (E2)
      +	E2, sizeof(THING)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	sizeof(THING) * E2
      +	E2, sizeof(THING)
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	(E1) * E2
      +	E1, E2
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	(E1) * (E2)
      +	E1, E2
        , ...)
      |
      - kmalloc
      + kmalloc_array
        (
      -	E1 * E2
      +	E1, E2
        , ...)
      )
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      6da2ec56
  5. 25 May, 2018 1 commit
  6. 11 Jan, 2018 1 commit
  7. 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
  8. 29 Oct, 2017 1 commit
  9. 06 Aug, 2017 1 commit
  10. 05 Feb, 2017 1 commit
  11. 27 Apr, 2016 1 commit
  12. 12 Feb, 2016 1 commit
  13. 18 Oct, 2015 1 commit
    • Andy Leiserson's avatar
      [PATCH] fix calculation of meta_bg descriptor backups · 904dad47
      Andy Leiserson authored
      
      
      "group" is the group where the backup will be placed, and is
      initialized to zero in the declaration. This meant that backups for
      meta_bg descriptors were erroneously written to the backup block group
      descriptors in groups 1 and (desc_per_block-1).
      
      Reproduction information:
        mke2fs -Fq -t ext4 -b 1024 -O ^resize_inode /tmp/foo.img 16G
        truncate -s 24G /tmp/foo.img
        losetup /dev/loop0 /tmp/foo.img
        mount /dev/loop0 /mnt
        resize2fs /dev/loop0
        umount /dev/loop0
        dd if=/dev/zero of=/dev/loop0 bs=1024 count=2
        e2fsck -fy /dev/loop0
        losetup -d /dev/loop0
      Signed-off-by: default avatarAndy Leiserson <andy@leiserson.org>
      Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
      Cc: stable@vger.kernel.org
      904dad47
  14. 17 Oct, 2015 1 commit
  15. 03 May, 2015 1 commit
    • Jan Kara's avatar
      ext4: fix growing of tiny filesystems · 2c869b26
      Jan Kara authored
      
      
      The estimate of necessary transaction credits in ext4_flex_group_add()
      is too pessimistic. It reserves credit for sb, resize inode, and resize
      inode dindirect block for each group added in a flex group although they
      are always the same block and thus it is enough to account them only
      once. Also the number of modified GDT block is overestimated since we
      fit EXT4_DESC_PER_BLOCK(sb) descriptors in one block.
      
      Make the estimation more precise. That reduces number of requested
      credits enough that we can grow 20 MB filesystem (which has 1 MB
      journal, 79 reserved GDT blocks, and flex group size 16 by default).
      Signed-off-by: default avatarJan Kara <jack@suse.cz>
      Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
      Reviewed-by: default avatarEric Sandeen <sandeen@redhat.com>
      2c869b26
  16. 27 Dec, 2014 1 commit
  17. 20 Nov, 2014 1 commit
  18. 30 Oct, 2014 1 commit
  19. 13 Oct, 2014 1 commit
  20. 03 Sep, 2014 1 commit
  21. 13 May, 2014 1 commit
  22. 18 Apr, 2014 1 commit
  23. 16 Feb, 2014 2 commits
    • Theodore Ts'o's avatar
      ext4: fix online resize with a non-standard blocks per group setting · 3d2660d0
      Theodore Ts'o authored
      
      
      The set_flexbg_block_bitmap() function assumed that the number of
      blocks in a blockgroup was sb->blocksize * 8, which is normally true,
      but not always!  Use EXT4_BLOCKS_PER_GROUP(sb) instead, to fix block
      bitmap corruption after:
      
      mke2fs -t ext4 -g 3072 -i 4096 /dev/vdd 1G
      mount -t ext4 /dev/vdd /vdd
      resize2fs /dev/vdd 8G
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Reported-by: default avatarJon Bernard <jbernard@tuxion.com>
      Cc: stable@vger.kernel.org
      3d2660d0
    • Theodore Ts'o's avatar
      ext4: fix online resize with very large inode tables · b93c9535
      Theodore Ts'o authored
      
      
      If a file system has a large number of inodes per block group, all of
      the metadata blocks in a flex_bg may be larger than what can fit in a
      single block group.  Unfortunately, ext4_alloc_group_tables() in
      resize.c was never tested to see if it would handle this case
      correctly, and there were a large number of bugs which caused the
      following sequence to result in a BUG_ON:
      
      kernel bug at fs/ext4/resize.c:409!
         ...
      call trace:
       [<ffffffff81256768>] ext4_flex_group_add+0x1448/0x1830
       [<ffffffff81257de2>] ext4_resize_fs+0x7b2/0xe80
       [<ffffffff8123ac50>] ext4_ioctl+0xbf0/0xf00
       [<ffffffff811c111d>] do_vfs_ioctl+0x2dd/0x4b0
       [<ffffffff811b9df2>] ? final_putname+0x22/0x50
       [<ffffffff811c1371>] sys_ioctl+0x81/0xa0
       [<ffffffff81676aa9>] system_call_fastpath+0x16/0x1b
      code: c8 4c 89 df e8 41 96 f8 ff 44 89 e8 49 01 c4 44 29 6d d4 0
      rip  [<ffffffff81254fa1>] set_flexbg_block_bitmap+0x171/0x180
      
      
      This can be reproduced with the following command sequence:
      
         mke2fs -t ext4 -i 4096 /dev/vdd 1G
         mount -t ext4 /dev/vdd /vdd
         resize2fs /dev/vdd 8G
      
      To fix this, we need to make sure the right thing happens when a block
      group's inode table straddles two block groups, which means the
      following bugs had to be fixed:
      
      1) Not clearing the BLOCK_UNINIT flag in the second block group in
         ext4_alloc_group_tables --- the was proximate cause of the BUG_ON.
      
      2) Incorrectly determining how many block groups contained contiguous
         free blocks in ext4_alloc_group_tables().
      
      3) Incorrectly setting the start of the next block range to be marked
         in use after a discontinuity in setup_new_flex_group_blocks().
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Cc: stable@vger.kernel.org
      b93c9535
  24. 01 Jul, 2013 1 commit
  25. 17 Jun, 2013 1 commit
  26. 06 Jun, 2013 1 commit
  27. 22 Apr, 2013 2 commits
  28. 04 Apr, 2013 1 commit
    • Lukas Czerner's avatar
      ext4: introduce ext4_get_group_number() · bd86298e
      Lukas Czerner authored
      
      
      Currently on many places in ext4 we're using
      ext4_get_group_no_and_offset() even though we're only interested in
      knowing the block group of the particular block, not the offset within
      the block group so we can use more efficient way to compute block
      group.
      
      This patch introduces ext4_get_group_number() which computes block
      group for a given block much more efficiently. Use this function
      instead of ext4_get_group_no_and_offset() everywhere where we're only
      interested in knowing the block group.
      Signed-off-by: default avatarLukas Czerner <lczerner@redhat.com>
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      bd86298e
  29. 12 Mar, 2013 1 commit
  30. 02 Mar, 2013 1 commit
  31. 09 Feb, 2013 1 commit
    • Theodore Ts'o's avatar
      ext4: pass context information to jbd2__journal_start() · 9924a92a
      Theodore Ts'o authored
      
      
      So we can better understand what bits of ext4 are responsible for
      long-running jbd2 handles, use jbd2__journal_start() so we can pass
      context information for logging purposes.
      
      The recommended way for finding the longer-running handles is:
      
         T=/sys/kernel/debug/tracing
         EVENT=$T/events/jbd2/jbd2_handle_stats
         echo "interval > 5" > $EVENT/filter
         echo 1 > $EVENT/enable
      
         ./run-my-fs-benchmark
      
         cat $T/trace > /tmp/problem-handles
      
      This will list handles that were active for longer than 20ms.  Having
      longer-running handles is bad, because a commit started at the wrong
      time could stall for those 20+ milliseconds, which could delay an
      fsync() or an O_SYNC operation.  Here is an example line from the
      trace file describing a handle which lived on for 311 jiffies, or over
      1.2 seconds:
      
      postmark-2917  [000] ....   196.435786: jbd2_handle_stats: dev 254,32 
         tid 570 type 2 line_no 2541 interval 311 sync 0 requested_blocks 1
         dirtied_blocks 0
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      9924a92a
  32. 13 Jan, 2013 1 commit
  33. 12 Jan, 2013 2 commits