Re: [PATCH 2/2] jbd2: remove all t_handle_lock statements

[Yongqiang Yang <xiaoqiangnk@gmail.com>]

On Thu, Dec 22, 2011 at 8:00 PM, Toshiyuki Okajima
<toshi.okajima@jp.fujitsu.com> wrote:
> Remove all t_handle_lock statements because they are not necessary anymore.
>
> Because there is read_lock(&journal->j_state_lock) or
> write_lock(&journal->j_state_lock) on all the forward codes beyond the place
> which needs a spin_lock(&transaction->t_handle_lock).
>
> Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
> Cc:
> ---
>  fs/jbd2/commit.c      |    4 ----
>  fs/jbd2/transaction.c |   18 +++---------------
>  include/linux/jbd2.h  |    8 --------
>  3 files changed, 3 insertions(+), 27 deletions(-)
>
> diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
> index 68d704d..1030d47 100644
> --- a/fs/jbd2/commit.c
> +++ b/fs/jbd2/commit.c
> @@ -364,22 +364,18 @@ void jbd2_journal_commit_transaction(journal_t *journal)
>        stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
>                                              stats.run.rs_locked);
>
> -       spin_lock(&commit_transaction->t_handle_lock);
>        while (atomic_read(&commit_transaction->t_updates)) {
>                DEFINE_WAIT(wait);
>
>                prepare_to_wait(&journal->j_wait_updates, &wait,
>                                        TASK_UNINTERRUPTIBLE);
>                if (atomic_read(&commit_transaction->t_updates)) {
> -                       spin_unlock(&commit_transaction->t_handle_lock);
>                        write_unlock(&journal->j_state_lock);
>                        schedule();
>                        write_lock(&journal->j_state_lock);
> -                       spin_lock(&commit_transaction->t_handle_lock);
>                }
>                finish_wait(&journal->j_wait_updates, &wait);
>        }
> -       spin_unlock(&commit_transaction->t_handle_lock);
>
>        J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
>                        journal->j_max_transaction_buffers);
> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index 76f2eca..7f84e3f 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -56,7 +56,6 @@ jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
>        transaction->t_start_time = ktime_get();
>        transaction->t_tid = journal->j_transaction_sequence++;
>        transaction->t_expires = jiffies + journal->j_commit_interval;
> -       spin_lock_init(&transaction->t_handle_lock);
>        atomic_set(&transaction->t_updates, 0);
>        atomic_set(&transaction->t_outstanding_credits, 0);
>        atomic_set(&transaction->t_handle_count, 0);
> @@ -100,10 +99,8 @@ static inline void update_t_max_wait(transaction_t *transaction,
>        if (jbd2_journal_enable_debug &&
>            time_after(transaction->t_start, ts)) {
>                ts = jbd2_time_diff(ts, transaction->t_start);
> -               spin_lock(&transaction->t_handle_lock);
>                if (ts > transaction->t_max_wait)
>                        transaction->t_max_wait = ts;
> -               spin_unlock(&transaction->t_handle_lock);
Hi Toshiyuki,

     I think you removed too much.  t_handle_lock is needed here to
protect t_max_wait.   I meant just removing t_handle_lock from where I
commented in your patch post out last time.

Yongqiang.
>        }
>  #endif
>  }
> @@ -401,19 +398,18 @@ int jbd2_journal_extend(handle_t *handle, int nblocks)
>                goto error_out;
>        }
>
> -       spin_lock(&transaction->t_handle_lock);
>        wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks;
>
>        if (wanted > journal->j_max_transaction_buffers) {
>                jbd_debug(3, "denied handle %p %d blocks: "
>                          "transaction too large\n", handle, nblocks);
> -               goto unlock;
> +               goto error_out;
>        }
>
>        if (wanted > __jbd2_log_space_left(journal)) {
>                jbd_debug(3, "denied handle %p %d blocks: "
>                          "insufficient log space\n", handle, nblocks);
> -               goto unlock;
> +               goto error_out;
>        }
>
>        handle->h_buffer_credits += nblocks;
> @@ -421,8 +417,6 @@ int jbd2_journal_extend(handle_t *handle, int nblocks)
>        result = 0;
>
>        jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
> -unlock:
> -       spin_unlock(&transaction->t_handle_lock);
>  error_out:
>        read_unlock(&journal->j_state_lock);
>  out:
> @@ -464,12 +458,10 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)
>        J_ASSERT(journal_current_handle() == handle);
>
>        read_lock(&journal->j_state_lock);
> -       spin_lock(&transaction->t_handle_lock);
>        atomic_sub(handle->h_buffer_credits,
>                   &transaction->t_outstanding_credits);
>        if (atomic_dec_and_test(&transaction->t_updates))
>                wake_up(&journal->j_wait_updates);
> -       spin_unlock(&transaction->t_handle_lock);
>
>        jbd_debug(2, "restarting handle %p\n", handle);
>        tid = transaction->t_tid;
> @@ -516,14 +508,10 @@ void jbd2_journal_lock_updates(journal_t *journal)
>                if (!transaction)
>                        break;
>
> -               spin_lock(&transaction->t_handle_lock);
> -               if (!atomic_read(&transaction->t_updates)) {
> -                       spin_unlock(&transaction->t_handle_lock);
> +               if (!atomic_read(&transaction->t_updates))
>                        break;
> -               }
>                prepare_to_wait(&journal->j_wait_updates, &wait,
>                                TASK_UNINTERRUPTIBLE);
> -               spin_unlock(&transaction->t_handle_lock);
>                write_unlock(&journal->j_state_lock);
>                schedule();
>                finish_wait(&journal->j_wait_updates, &wait);
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index 2092ea2..55f7a8c 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -440,9 +440,6 @@ struct transaction_chp_stats_s {
>  *    ->j_list_lock
>  *
>  *    j_state_lock
> - *    ->t_handle_lock
> - *
> - *    j_state_lock
>  *    ->j_list_lock                    (journal_unmap_buffer)
>  *
>  */
> @@ -538,11 +535,6 @@ struct transaction_s
>        struct list_head        t_inode_list;
>
>        /*
> -        * Protects info related to handles
> -        */
> -       spinlock_t              t_handle_lock;
> -
> -       /*
>         * Longest time some handle had to wait for running transaction
>         */
>        unsigned long           t_max_wait;
> --
> 1.5.5.6



-- 
Best Wishes
Yongqiang Yang
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