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Date: Thu, 22 Dec 2011 22:07:32 +0800
From: Yongqiang Yang <xiaoqiangnk@...il.com>
To: Toshiyuki Okajima <toshi.okajima@...fujitsu.com>
Cc: tytso@....edu, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] jbd2: remove all t_handle_lock statements
On Thu, Dec 22, 2011 at 8:00 PM, Toshiyuki Okajima
<toshi.okajima@...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@...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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