From: Ted Ts'o <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
ocfs2-devel@oss.oracle.com, John Stultz <johnstul@us.ibm.com>,
Keith Maanthey <kmannth@us.ibm.com>,
Eric Whitney <eric.whitney@hp.com>
Subject: Re: [PATCH -v2 1/3] jbd2: Use atomic variables to avoid taking t_handle_lock in jbd2_journal_stop
Date: Mon, 9 Aug 2010 15:05:13 -0400 [thread overview]
Message-ID: <20100809190513.GF3635@thunk.org> (raw)
In-Reply-To: <20100809170216.GB31969@atrey.karlin.mff.cuni.cz>
On Mon, Aug 09, 2010 at 07:02:16PM +0200, Jan Kara wrote:
> spin_lock(&journal->j_state_lock);
> spin_lock(&transaction->t_handle_lock);
> - transaction->t_outstanding_credits -= handle->h_buffer_credits;
> - transaction->t_updates--;
> -
> - if (!transaction->t_updates)
> + atomic_sub(handle->h_buffer_credits,
> + &transaction->t_outstanding_credits);
> + if (atomic_dec_and_test(&transaction->t_updates))
>
> After this a transaction can disappear so subsequent
> __jbd2_log_start_commit shouldn't dereference transaction->t_tid,
> right?
I think it should be ok because we're holding j_state_lock(), so the
transaction can't disappear until we release the j_state_lock.
- Ted
WARNING: multiple messages have this Message-ID (diff)
From: Ted Ts'o <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
ocfs2-devel@oss.oracle.com, John Stultz <johnstul@us.ibm.com>,
Keith Maanthey <kmannth@us.ibm.com>,
Eric Whitney <eric.whitney@hp.com>
Subject: [Ocfs2-devel] [PATCH -v2 1/3] jbd2: Use atomic variables to avoid taking t_handle_lock in jbd2_journal_stop
Date: Mon, 9 Aug 2010 15:05:13 -0400 [thread overview]
Message-ID: <20100809190513.GF3635@thunk.org> (raw)
In-Reply-To: <20100809170216.GB31969@atrey.karlin.mff.cuni.cz>
On Mon, Aug 09, 2010 at 07:02:16PM +0200, Jan Kara wrote:
> spin_lock(&journal->j_state_lock);
> spin_lock(&transaction->t_handle_lock);
> - transaction->t_outstanding_credits -= handle->h_buffer_credits;
> - transaction->t_updates--;
> -
> - if (!transaction->t_updates)
> + atomic_sub(handle->h_buffer_credits,
> + &transaction->t_outstanding_credits);
> + if (atomic_dec_and_test(&transaction->t_updates))
>
> After this a transaction can disappear so subsequent
> __jbd2_log_start_commit shouldn't dereference transaction->t_tid,
> right?
I think it should be ok because we're holding j_state_lock(), so the
transaction can't disappear until we release the j_state_lock.
- Ted
next prev parent reply other threads:[~2010-08-09 19:05 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-04 16:39 [PATCH -v2 0/3] jbd2 scalability patches Theodore Ts'o
2010-08-04 16:39 ` [Ocfs2-devel] " Theodore Ts'o
2010-08-04 16:39 ` [PATCH -v2 1/3] jbd2: Use atomic variables to avoid taking t_handle_lock in jbd2_journal_stop Theodore Ts'o
2010-08-04 16:39 ` [Ocfs2-devel] " Theodore Ts'o
2010-08-09 17:02 ` Jan Kara
2010-08-09 17:02 ` [Ocfs2-devel] " Jan Kara
2010-08-09 19:05 ` Ted Ts'o [this message]
2010-08-09 19:05 ` Ted Ts'o
2010-08-09 19:45 ` Jan Kara
2010-08-09 19:45 ` [Ocfs2-devel] " Jan Kara
2010-08-10 16:30 ` Ted Ts'o
2010-08-10 16:30 ` [Ocfs2-devel] " Ted Ts'o
2010-08-11 22:16 ` Jan Kara
2010-08-11 22:16 ` [Ocfs2-devel] " Jan Kara
2010-08-04 16:39 ` [PATCH -v2 2/3] jbd2: Change j_state_lock to be a rwlock_t Theodore Ts'o
2010-08-04 16:39 ` [Ocfs2-devel] " Theodore Ts'o
2010-08-04 16:39 ` [PATCH -v2 3/3] jbd2: Remove t_handle_lock from start_this_handle() Theodore Ts'o
2010-08-04 16:39 ` [Ocfs2-devel] " Theodore Ts'o
2010-08-05 1:58 ` [PATCH -v2 0/3] jbd2 scalability patches john stultz
2010-08-05 1:58 ` [Ocfs2-devel] " john stultz
2010-08-05 5:42 ` Ted Ts'o
2010-08-05 5:42 ` [Ocfs2-devel] " Ted Ts'o
2010-08-05 17:42 ` john stultz
2010-08-05 17:42 ` [Ocfs2-devel] " john stultz
2010-08-09 16:06 ` Joel Becker
2010-08-09 16:06 ` Joel Becker
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