simplify-code-flow-in-do_get_write_access

   1 jbd2: simplify code flow in do_get_write_access()
   2
   3 From: Jan Kara <jack@suse.cz>
   4
   5 needs_copy is set only in one place in do_get_write_access(), just move
   6 the frozen buffer copying into that place and factor it out to a
   7 separate function to make do_get_write_access() slightly more readable.
   8
   9 Signed-off-by: Jan Kara <jack@suse.cz>
  10 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  11 ---
  12  fs/jbd2/transaction.c | 49 +++++++++++++++++++++++++------------------------
  13  1 file changed, 25 insertions(+), 24 deletions(-)
  14
  15 diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
  16 index 5f09370c90a8..2b75f0f109be 100644
  17 --- a/fs/jbd2/transaction.c
  18 +++ b/fs/jbd2/transaction.c
  19 @@ -763,6 +763,30 @@ static void warn_dirty_buffer(struct buffer_head *bh)
  20                bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
  21  }
  22
  23 +/* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
  24 +static void jbd2_freeze_jh_data(struct journal_head *jh)
  25 +{
  26 +       struct page *page;
  27 +       int offset;
  28 +       char *source;
  29 +       struct buffer_head *bh = jh2bh(jh);
  30 +
  31 +       J_EXPECT_JH(jh, buffer_uptodate(bh), "Possible IO failure.\n");
  32 +       page = bh->b_page;
  33 +       offset = offset_in_page(bh->b_data);
  34 +       source = kmap_atomic(page);
  35 +       /* Fire data frozen trigger just before we copy the data */
  36 +       jbd2_buffer_frozen_trigger(jh, source + offset, jh->b_triggers);
  37 +       memcpy(jh->b_frozen_data, source + offset, bh->b_size);
  38 +       kunmap_atomic(source);
  39 +
  40 +       /*
  41 +        * Now that the frozen data is saved off, we need to store any matching
  42 +        * triggers.
  43 +        */
  44 +       jh->b_frozen_triggers = jh->b_triggers;
  45 +}
  46 +
  47  /*
  48   * If the buffer is already part of the current transaction, then there
  49   * is nothing we need to do.  If it is already part of a prior
  50 @@ -782,7 +806,6 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
  51         journal_t *journal;
  52         int error;
  53         char *frozen_buffer = NULL;
  54 -       int need_copy = 0;
  55         unsigned long start_lock, time_lock;
  56
  57         WARN_ON(!transaction);
  58 @@ -940,7 +963,7 @@ repeat:
  59                         }
  60                         jh->b_frozen_data = frozen_buffer;
  61                         frozen_buffer = NULL;
  62 -                       need_copy = 1;
  63 +                       jbd2_freeze_jh_data(jh);
  64                 }
  65                 jh->b_next_transaction = transaction;
  66         }
  67 @@ -961,28 +984,6 @@ repeat:
  68         }
  69
  70  done:
  71 -       if (need_copy) {
  72 -               struct page *page;
  73 -               int offset;
  74 -               char *source;
  75 -
  76 -               J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
  77 -                           "Possible IO failure.\n");
  78 -               page = jh2bh(jh)->b_page;
  79 -               offset = offset_in_page(jh2bh(jh)->b_data);
  80 -               source = kmap_atomic(page);
  81 -               /* Fire data frozen trigger just before we copy the data */
  82 -               jbd2_buffer_frozen_trigger(jh, source + offset,
  83 -                                          jh->b_triggers);
  84 -               memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
  85 -               kunmap_atomic(source);
  86 -
  87 -               /*
  88 -                * Now that the frozen data is saved off, we need to store
  89 -                * any matching triggers.
  90 -                */
  91 -               jh->b_frozen_triggers = jh->b_triggers;
  92 -       }
  93         jbd_unlock_bh_state(bh);
  94
  95         /*
  96 --
  97 2.1.4