From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Monakhov Subject: Re: [PATCH 1/2] jbd: Provide function to check whether transaction will issue data barrier Date: Tue, 27 Apr 2010 07:42:49 +0400 Message-ID: <87eii1d0hy.fsf@openvz.org> References: <1272312659-16468-1-git-send-email-jack@suse.cz> <1272312659-16468-2-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Jan Kara Return-path: Received: from mail-bw0-f219.google.com ([209.85.218.219]:56544 "EHLO mail-bw0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753027Ab0D0Dmy (ORCPT ); Mon, 26 Apr 2010 23:42:54 -0400 Received: by bwz19 with SMTP id 19so109817bwz.21 for ; Mon, 26 Apr 2010 20:42:52 -0700 (PDT) In-Reply-To: <1272312659-16468-2-git-send-email-jack@suse.cz> (Jan Kara's message of "Mon, 26 Apr 2010 22:10:58 +0200") Sender: linux-ext4-owner@vger.kernel.org List-ID: Jan Kara 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 > --- > 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 *);