track-more-dependencies-on-transaction-commit

   1 jbd2: track more dependencies on transaction commit
   2
   3 From: Jan Kara <jack@suse.cz>
   4
   5 So far we were tracking only dependency on transaction commit due to
   6 starting a new handle (which may require commit to start a new
   7 transaction). Now add tracking also for other cases where we wait for
   8 transaction commit. This way lockdep can catch deadlocks e. g. because we
   9 call jbd2_journal_stop() for a synchronous handle with some locks held
  10 which rank below transaction start.
  11
  12 Signed-off-by: Jan Kara <jack@suse.cz>
  13 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  14 ---
  15  fs/jbd2/journal.c     | 1 +
  16  fs/jbd2/transaction.c | 4 ++++
  17  include/linux/jbd2.h  | 6 ++++++
  18  3 files changed, 11 insertions(+)
  19
  20 diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
  21 index 208e4058040b..fc1d7a39b082 100644
  22 --- a/fs/jbd2/journal.c
  23 +++ b/fs/jbd2/journal.c
  24 @@ -691,6 +691,7 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
  25  {
  26         int err = 0;
  27
  28 +       jbd2_might_wait_for_commit(journal);
  29         read_lock(&journal->j_state_lock);
  30  #ifdef CONFIG_JBD2_DEBUG
  31         if (!tid_geq(journal->j_commit_request, tid)) {
  32 diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
  33 index c0065040c5be..b5bc3e249163 100644
  34 --- a/fs/jbd2/transaction.c
  35 +++ b/fs/jbd2/transaction.c
  36 @@ -182,6 +182,8 @@ static int add_transaction_credits(journal_t *journal, int blocks,
  37         int needed;
  38         int total = blocks + rsv_blocks;
  39
  40 +       jbd2_might_wait_for_commit(journal);
  41 +
  42         /*
  43          * If the current transaction is locked down for commit, wait
  44          * for the lock to be released.
  45 @@ -695,6 +697,8 @@ void jbd2_journal_lock_updates(journal_t *journal)
  46  {
  47         DEFINE_WAIT(wait);
  48
  49 +       jbd2_might_wait_for_commit(journal);
  50 +
  51         write_lock(&journal->j_state_lock);
  52         ++journal->j_barrier_count;
  53
  54 diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
  55 index f6232b28eadc..64f8b594dd5a 100644
  56 --- a/include/linux/jbd2.h
  57 +++ b/include/linux/jbd2.h
  58 @@ -1045,6 +1045,12 @@ struct journal_s
  59  #endif
  60  };
  61
  62 +#define jbd2_might_wait_for_commit(j) \
  63 +       do { \
  64 +               rwsem_acquire(&j->j_trans_commit_map, 0, 0, _THIS_IP_); \
  65 +               rwsem_release(&j->j_trans_commit_map, 1, _THIS_IP_); \
  66 +       } while (0)
  67 +
  68  /* journal feature predicate functions */
  69  #define JBD2_FEATURE_COMPAT_FUNCS(name, flagname) \
  70  static inline bool jbd2_has_feature_##name(journal_t *j) \
  71 --
  72 2.6.6
  73
  74