Jan Kara <jack@xxxxxxx> writes:
> Provide a function which returns whether a transaction with given tid
> will send a barrier to the filesystem device. The function will be used
> by ext3 to detect whether fsync needs to send a separate barrier or not.
Agree. Except the fact that in case of j_dev != j_fs_dev jbd is still
broken. I'm plan to post back-port from jbd2 which makes
journal_trans_will_send_data_barrier() more complex. It have to analyze
commit_transaction->t_flushed_data_blocks.
>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/jbd/commit.c | 8 +++++++-
> fs/jbd/journal.c | 33 +++++++++++++++++++++++++++++++++
> include/linux/jbd.h | 3 ++-
> 3 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
> index ecb44c9..28a9dda 100644
> --- a/fs/jbd/commit.c
> +++ b/fs/jbd/commit.c
> @@ -786,6 +786,12 @@ wait_for_iobuf:
>
> jbd_debug(3, "JBD: commit phase 6\n");
>
> + /* All metadata is written, now write commit record and do cleanup */
> + spin_lock(&journal->j_state_lock);
> + J_ASSERT(commit_transaction->t_state == T_COMMIT);
> + commit_transaction->t_state = T_COMMIT_RECORD;
> + spin_unlock(&journal->j_state_lock);
> +
> if (journal_write_commit_record(journal, commit_transaction))
> err = -EIO;
>
> @@ -923,7 +929,7 @@ restart_loop:
>
> jbd_debug(3, "JBD: commit phase 8\n");
>
> - J_ASSERT(commit_transaction->t_state == T_COMMIT);
> + J_ASSERT(commit_transaction->t_state == T_COMMIT_RECORD);
>
> commit_transaction->t_state = T_FINISHED;
> J_ASSERT(commit_transaction == journal->j_committing_transaction);
> diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
> index bd224ee..99c7194 100644
> --- a/fs/jbd/journal.c
> +++ b/fs/jbd/journal.c
> @@ -565,6 +565,38 @@ int log_wait_commit(journal_t *journal, tid_t tid)
> }
>
> /*
> + * Return 1 if a given transaction has not yet sent barrier request
> + * connected with a transaction commit. If 0 is returned, transaction
> + * may or may not have sent the barrier. Used to avoid sending barrier
> + * twice in common cases.
> + */
> +int journal_trans_will_send_data_barrier(journal_t *journal, tid_t tid)
> +{
> + int ret = 0;
> + transaction_t *commit_trans;
> +
> + if (!(journal->j_flags & JFS_BARRIER))
> + return 0;
> + spin_lock(&journal->j_state_lock);
> + /* Transaction already committed? */
> + if (tid_geq(journal->j_commit_sequence, tid))
> + goto out;
> + /*
> + * Transaction is being committed and we already proceeded to
> + * writing commit record?
> + */
> + commit_trans = journal->j_committing_transaction;
> + if (commit_trans && commit_trans->t_tid == tid &&
> + commit_trans->t_state >= T_COMMIT_RECORD)
> + goto out;
> + ret = 1;
> +out:
> + spin_unlock(&journal->j_state_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL(journal_commit_will_send_barrier);
> +
> +/*
> * Log buffer allocation routines:
> */
>
> @@ -1157,6 +1189,7 @@ int journal_destroy(journal_t *journal)
> {
> int err = 0;
>
> +
> /* Wait for the commit thread to wake up and die. */
> journal_kill_thread(journal);
>
> diff --git a/include/linux/jbd.h b/include/linux/jbd.h
> index 516a2a2..e069650 100644
> --- a/include/linux/jbd.h
> +++ b/include/linux/jbd.h
> @@ -427,9 +427,9 @@ struct transaction_s
> enum {
> T_RUNNING,
> T_LOCKED,
> - T_RUNDOWN,
> T_FLUSH,
> T_COMMIT,
> + T_COMMIT_RECORD,
> T_FINISHED
> } t_state;
>
> @@ -991,6 +991,7 @@ int journal_start_commit(journal_t *journal, tid_t *tid);
> int journal_force_commit_nested(journal_t *journal);
> int log_wait_commit(journal_t *journal, tid_t tid);
> int log_do_checkpoint(journal_t *journal);
> +int journal_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
>
> void __log_wait_for_space(journal_t *journal);
> extern void __journal_drop_transaction(journal_t *, transaction_t *);
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