1. 09 Feb, 2013 8 commits
    • Theodore Ts'o's avatar
      ext4: start handle at the last possible moment when creating inodes · 1139575a
      Theodore Ts'o authored
      
      
      In ext4_{create,mknod,mkdir,symlink}(), don't start the journal handle
      until the inode has been succesfully allocated.  In order to do this,
      we need to start the handle in the ext4_new_inode().  So create a new
      variant of this function, ext4_new_inode_start_handle(), so the handle
      can be created at the last possible minute, before we need to modify
      the inode allocation bitmap block.
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      1139575a
    • Theodore Ts'o's avatar
      ext4: fix the number of credits needed for acl ops with inline data · 95eaefbd
      Theodore Ts'o authored
      
      
      Operations which modify extended attributes may need extra journal
      credits if inline data is used, since there is a chance that some
      extended attributes may need to get pushed to an external attribute
      block.
      
      Changes to reflect this was made in xattr.c, but they were missed in
      fs/ext4/acl.c.  To fix this, abstract the calculation of the number of
      credits needed for xattr operations to an inline function defined in
      ext4_jbd2.h, and use it in acl.c and xattr.c.
      
      Also move the function declarations used in inline.c from xattr.h
      (where they are non-obviously hidden, and caused problems since
      ext4_jbd2.h needs to use the function ext4_has_inline_data), and move
      them to ext4.h.
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Reviewed-by: default avatarTao Ma <boyu.mt@taobao.com>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      95eaefbd
    • Theodore Ts'o's avatar
      ext4: fix the number of credits needed for ext4_unlink() and ext4_rmdir() · 64044abf
      Theodore Ts'o authored
      
      
      The ext4_unlink() and ext4_rmdir() don't actually release the blocks
      associated with the file/directory.  This gets done in a separate jbd2
      handle called via ext4_evict_inode().  Thus, we don't need to reserve
      lots of journal credits for the truncate.
      
      Note that using too many journal credits is non-optimal because it can
      leading to the journal transmit getting closed too early, before it is
      strictly necessary.
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      64044abf
    • Theodore Ts'o's avatar
      ext4: fix the number of credits needed for ext4_ext_migrate() · 4b217630
      Theodore Ts'o authored
      
      
      The migration ioctl creates a temporary inode.  Since this inode is
      never linked to a directory, we don't need to reserve journal credits
      required for modifying the directory.
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      4b217630
    • Theodore Ts'o's avatar
      ext4: start handle at the last possible moment in ext4_rmdir() · 8dcfaad2
      Theodore Ts'o authored
      
      
      Don't start the jbd2 transaction handle until after the directory
      entry has been found, to minimize the amount of time that a handle is
      held active.
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      8dcfaad2
    • Theodore Ts'o's avatar
      ext4: start handle at the last possible moment in ext4_unlink() · 931b6864
      Theodore Ts'o authored
      
      
      Don't start the jbd2 transaction handle until after the directory
      entry has been found, to minimize the amount of time that a handle is
      held active.
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      931b6864
    • Theodore Ts'o's avatar
      ext4: grab page before starting transaction handle in write_begin() · 47564bfb
      Theodore Ts'o authored
      
      
      The grab_cache_page_write_begin() function can potentially sleep for a
      long time, since it may need to do memory allocation which can block
      if the system is under significant memory pressure, and because it may
      be blocked on page writeback.  If it does take a long time to grab the
      page, it's better that we not hold an active jbd2 handle.
      
      So grab a handle on the page first, and _then_ start the transaction
      handle.
      
      This commit fixes the following long transaction handle hold time:
      
      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>
      Reviewed-by: default avatarJan Kara <jack@suse.cz>
      47564bfb
    • 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
  2. 08 Feb, 2013 2 commits
  3. 07 Feb, 2013 2 commits
  4. 04 Feb, 2013 1 commit
    • Theodore Ts'o's avatar
      ext4: optimize mballoc for large allocations · 40ae3487
      Theodore Ts'o authored
      
      
      The ext4 block allocator only maintains buddy bitmaps for chunks which
      are less than or equal to one quarter of a block group.  That is, for
      a file aystem with a 1k blocksize, and where the number of blocks in a
      block group is 8192 blocks, the largest chunk size tracked by buddy
      bitmaps is 2048 blocks.
      
      For a file system with a 4k blocksize, and where the number of blocks
      in a block group is 32768 blocks, the largest chunk size tracked by
      buddy bitmaps is 8192 blocks.
      
      To work around this code, mballoc.c before this commit would truncate
      allocation requests to the number of blocks in a block group minus 10.
      Why 10?  Aside from being a completely arbitrary number, it avoids
      block allocation to be a power of two larger than 25% of the block
      group.  If you try to explicitly fallocate 50% of the block group
      size, this will demonstrate the problem; the block allocation code
      will scan the all of the blocks in the file system with cr==0 (since
      the request is for a natural power of two), but then completely fail
      for all blocks groups, since the buddy bitmaps don't track chunk sizes
      of 50% of the block group.
      
      To fix this, in these we use ext4_mb_complex_scan_group() instead of
      ext4_mb_simple_scan_group().
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Cc: Andreas Dilger <adilger@dilger.ca>
      40ae3487
  5. 03 Feb, 2013 4 commits
  6. 02 Feb, 2013 4 commits
  7. 30 Jan, 2013 2 commits
  8. 29 Jan, 2013 8 commits
  9. 28 Jan, 2013 8 commits
  10. 25 Jan, 2013 1 commit