aneesh-6-call-journal-commit-without-holding-j_list_lock

   1 jbd2: Call journal commit callback without holding j_list_lock
   2
   3 From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
   4
   5 Avoid freeing the transaction in __jbd2_journal_drop_transaction() so
   6 the journal commit callback can run without holding j_list_lock, to
   7 avoid lock contention on this spinlock.
   8
   9 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  10 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  11 ---
  12  fs/jbd2/checkpoint.c |    2 +-
  13  fs/jbd2/commit.c     |   13 ++++++++-----
  14  include/linux/jbd2.h |    4 ++--
  15  3 files changed, 11 insertions(+), 8 deletions(-)
  16
  17 diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
  18 index 1c10ce5..ad1d2d9 100644
  19 --- a/fs/jbd2/checkpoint.c
  20 +++ b/fs/jbd2/checkpoint.c
  21 @@ -682,6 +682,7 @@ int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
  22            safely remove this transaction from the log */
  23
  24         __jbd2_journal_drop_transaction(journal, transaction);
  25 +       kfree(transaction);
  26
  27         /* Just in case anybody was waiting for more transactions to be
  28             checkpointed... */
  29 @@ -756,5 +757,4 @@ void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transact
  30         J_ASSERT(journal->j_running_transaction != transaction);
  31
  32         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
  33 -       kfree(transaction);
  34  }
  35 diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
  36 index b3bcb26..5befb2d 100644
  37 --- a/fs/jbd2/commit.c
  38 +++ b/fs/jbd2/commit.c
  39 @@ -340,7 +340,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
  40         int space_left = 0;
  41         int first_tag = 0;
  42         int tag_flag;
  43 -       int i;
  44 +       int i, to_free = 0;
  45         int tag_bytes = journal_tag_bytes(journal);
  46         struct buffer_head *cbh = NULL; /* For transactional checksums */
  47         __u32 crc32_sum = ~0;
  48 @@ -988,12 +988,10 @@ void jbd2_journal_commit_transaction(journal_t *journal)
  49                 journal->j_average_commit_time = commit_time;
  50         spin_unlock(&journal->j_state_lock);
  51
  52 -       if (journal->j_commit_callback)
  53 -               journal->j_commit_callback(journal, commit_transaction);
  54 -
  55         if (commit_transaction->t_checkpoint_list == NULL &&
  56             commit_transaction->t_checkpoint_io_list == NULL) {
  57                 __jbd2_journal_drop_transaction(journal, commit_transaction);
  58 +               to_free = 1;
  59         } else {
  60                 if (journal->j_checkpoint_transactions == NULL) {
  61                         journal->j_checkpoint_transactions = commit_transaction;
  62 @@ -1012,11 +1010,16 @@ void jbd2_journal_commit_transaction(journal_t *journal)
  63         }
  64         spin_unlock(&journal->j_list_lock);
  65
  66 +       if (journal->j_commit_callback)
  67 +               journal->j_commit_callback(journal, commit_transaction);
  68 +
  69         trace_mark(jbd2_end_commit, "dev %s transaction %d head %d",
  70 -                  journal->j_devname, journal->j_commit_sequence,
  71 +                  journal->j_devname, commit_transaction->t_tid,
  72                    journal->j_tail_sequence);
  73         jbd_debug(1, "JBD: commit %d complete, head %d\n",
  74                   journal->j_commit_sequence, journal->j_tail_sequence);
  75 +       if (to_free)
  76 +               kfree(commit_transaction);
  77
  78         wake_up(&journal->j_wait_done_commit);
  79  }
  80 diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
  81 index fdbd0bf..4932b34 100644
  82 --- a/include/linux/jbd2.h
  83 +++ b/include/linux/jbd2.h
  84 @@ -1170,8 +1170,8 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
  85  int jbd2_log_do_checkpoint(journal_t *journal);
  86
  87  void __jbd2_log_wait_for_space(journal_t *journal);
  88 -extern void    __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
  89 -extern int     jbd2_cleanup_journal_tail(journal_t *);
  90 +extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
  91 +extern int jbd2_cleanup_journal_tail(journal_t *);
  92
  93  /* Debugging code only: */
  94
  95 --
  96 1.6.0.3.514.g2f91b
  97
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