optimize-block-allocations-on-grow-indepth

   1 ext4: optimize block allocation on grow indepth
   2
   3 From: Dmitry Monakhov <dmonakhov@openvz.org>
   4
   5 It is reasonable to prepend newly created index to older one.
   6
   7 [ Dropped no longer used function parameter newext. -tytso ]
   8
   9 Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
  10 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  11 ---
  12  fs/ext4/extents.c | 20 ++++++++++++++------
  13  1 file changed, 14 insertions(+), 6 deletions(-)
  14
  15 diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
  16 index 8170b32..c3ed9af2 100644
  17 --- a/fs/ext4/extents.c
  18 +++ b/fs/ext4/extents.c
  19 @@ -1263,16 +1263,24 @@ cleanup:
  20   *   just created block
  21   */
  22  static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
  23 -                                unsigned int flags,
  24 -                                struct ext4_extent *newext)
  25 +                                unsigned int flags)
  26  {
  27         struct ext4_extent_header *neh;
  28         struct buffer_head *bh;
  29 -       ext4_fsblk_t newblock;
  30 +       ext4_fsblk_t newblock, goal = 0;
  31 +       struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
  32         int err = 0;
  33
  34 -       newblock = ext4_ext_new_meta_block(handle, inode, NULL,
  35 -               newext, &err, flags);
  36 +       /* Try to prepend new index to old one */
  37 +       if (ext_depth(inode))
  38 +               goal = ext4_idx_pblock(EXT_FIRST_INDEX(ext_inode_hdr(inode)));
  39 +       if (goal > le32_to_cpu(es->s_first_data_block)) {
  40 +               flags |= EXT4_MB_HINT_TRY_GOAL;
  41 +               goal--;
  42 +       } else
  43 +               goal = ext4_inode_to_goal_block(inode);
  44 +       newblock = ext4_new_meta_blocks(handle, inode, goal, flags,
  45 +                                       NULL, &err);
  46         if (newblock == 0)
  47                 return err;
  48
  49 @@ -1373,7 +1381,7 @@ repeat:
  50                         err = PTR_ERR(path);
  51         } else {
  52                 /* tree is full, time to grow in depth */
  53 -               err = ext4_ext_grow_indepth(handle, inode, mb_flags, newext);
  54 +               err = ext4_ext_grow_indepth(handle, inode, mb_flags);
  55                 if (err)
  56                         goto out;
  57