[PATCH 2/2] jbd: Refine commit writeout logic

[Jan Kara]

Currently we write out all journal buffers in WRITE_SYNC mode. This improves
performance for fsync heavy workloads but hinders performance when writes
are mostly asynchronous. So add possibility for callers starting a transaction
commit to specify whether they are going to wait for the commit and submit
journal writes in WRITE_SYNC mode only in that case.

Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 fs/ext3/fsync.c      |    2 +-
 fs/ext3/super.c      |    2 +-
 fs/jbd/checkpoint.c  |    2 +-
 fs/jbd/commit.c      |    4 ++--
 fs/jbd/journal.c     |   19 ++++++++++---------
 fs/jbd/transaction.c |    9 ++++-----
 include/linux/jbd.h  |   21 ++++++++++++---------
 7 files changed, 31 insertions(+), 28 deletions(-)

diff --git a/fs/ext3/fsync.c b/fs/ext3/fsync.c
index 09b13bb..5396dd6 100644
--- a/fs/ext3/fsync.c
+++ b/fs/ext3/fsync.c
@@ -81,7 +81,7 @@ int ext3_sync_file(struct file *file, int datasync)
 	if (test_opt(inode->i_sb, BARRIER) &&
 	    !journal_trans_will_send_data_barrier(journal, commit_tid))
 		needs_barrier = 1;
-	log_start_commit(journal, commit_tid);
+	log_start_commit(journal, commit_tid, true);
 	ret = log_wait_commit(journal, commit_tid);
 
 	/*
diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 85c8cc8..58a4424 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2497,7 +2497,7 @@ static int ext3_sync_fs(struct super_block *sb, int wait)
 {
 	tid_t target;
 
-	if (journal_start_commit(EXT3_SB(sb)->s_journal, &target)) {
+	if (journal_start_commit(EXT3_SB(sb)->s_journal, &target, true)) {
 		if (wait)
 			log_wait_commit(EXT3_SB(sb)->s_journal, target);
 	}
diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c
index e4b87bc..26ca2c3 100644
--- a/fs/jbd/checkpoint.c
+++ b/fs/jbd/checkpoint.c
@@ -297,7 +297,7 @@ static int __process_buffer(journal_t *journal, struct journal_head *jh,
 
 		spin_unlock(&journal->j_list_lock);
 		jbd_unlock_bh_state(bh);
-		log_start_commit(journal, tid);
+		log_start_commit(journal, tid, true);
 		log_wait_commit(journal, tid);
 		ret = 1;
 	} else if (!buffer_dirty(bh)) {
diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
index 34a4861..ac188cb 100644
--- a/fs/jbd/commit.c
+++ b/fs/jbd/commit.c
@@ -294,7 +294,7 @@ void journal_commit_transaction(journal_t *journal)
 	int first_tag = 0;
 	int tag_flag;
 	int i;
-	int write_op = WRITE_SYNC;
+	int write_op = WRITE;
 
 	/*
 	 * First job: lock down the current transaction and wait for
@@ -332,7 +332,7 @@ void journal_commit_transaction(journal_t *journal)
 	 * we unplug the device. We don't do explicit unplugging in here,
 	 * instead we rely on sync_buffer() doing the unplug for us.
 	 */
-	if (commit_transaction->t_synchronous_commit)
+	if (tid_geq(journal->j_commit_waited, commit_transaction->t_tid))
 		write_op = WRITE_SYNC_PLUG;
 	spin_lock(&commit_transaction->t_handle_lock);
 	while (commit_transaction->t_updates) {
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index da1b5e4..5743b4c 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -434,7 +434,7 @@ int __log_space_left(journal_t *journal)
 /*
  * Called under j_state_lock.  Returns true if a transaction commit was started.
  */
-int __log_start_commit(journal_t *journal, tid_t target)
+int __log_start_commit(journal_t *journal, tid_t target, bool will_wait)
 {
 	/*
 	 * Are we already doing a recent enough commit?
@@ -444,7 +444,8 @@ int __log_start_commit(journal_t *journal, tid_t target)
 		 * We want a new commit: OK, mark the request and wakeup the
 		 * commit thread.  We do _not_ do the commit ourselves.
 		 */
-
+		if (will_wait && !tid_geq(journal->j_commit_waited, target))
+			journal->j_commit_waited = target;
 		journal->j_commit_request = target;
 		jbd_debug(1, "JBD: requesting commit %d/%d\n",
 			  journal->j_commit_request,
@@ -455,12 +456,12 @@ int __log_start_commit(journal_t *journal, tid_t target)
 	return 0;
 }
 
-int log_start_commit(journal_t *journal, tid_t tid)
+int log_start_commit(journal_t *journal, tid_t tid, bool will_wait)
 {
 	int ret;
 
 	spin_lock(&journal->j_state_lock);
-	ret = __log_start_commit(journal, tid);
+	ret = __log_start_commit(journal, tid, will_wait);
 	spin_unlock(&journal->j_state_lock);
 	return ret;
 }
@@ -483,7 +484,7 @@ int journal_force_commit_nested(journal_t *journal)
 	spin_lock(&journal->j_state_lock);
 	if (journal->j_running_transaction && !current->journal_info) {
 		transaction = journal->j_running_transaction;
-		__log_start_commit(journal, transaction->t_tid);
+		__log_start_commit(journal, transaction->t_tid, true);
 	} else if (journal->j_committing_transaction)
 		transaction = journal->j_committing_transaction;
 
@@ -503,7 +504,7 @@ int journal_force_commit_nested(journal_t *journal)
  * if a transaction is going to be committed (or is currently already
  * committing), and fills its tid in at *ptid
  */
-int journal_start_commit(journal_t *journal, tid_t *ptid)
+int journal_start_commit(journal_t *journal, tid_t *ptid, bool will_wait)
 {
 	int ret = 0;
 
@@ -511,7 +512,7 @@ int journal_start_commit(journal_t *journal, tid_t *ptid)
 	if (journal->j_running_transaction) {
 		tid_t tid = journal->j_running_transaction->t_tid;
 
-		__log_start_commit(journal, tid);
+		__log_start_commit(journal, tid, will_wait);
 		/* There's a running transaction and we've just made sure
 		 * it's commit has been scheduled. */
 		if (ptid)
@@ -1439,7 +1440,7 @@ int journal_flush(journal_t *journal)
 	/* Force everything buffered to the log... */
 	if (journal->j_running_transaction) {
 		transaction = journal->j_running_transaction;
-		__log_start_commit(journal, transaction->t_tid);
+		__log_start_commit(journal, transaction->t_tid, true);
 	} else if (journal->j_committing_transaction)
 		transaction = journal->j_committing_transaction;
 
@@ -1573,7 +1574,7 @@ static void __journal_abort_hard(journal_t *journal)
 	journal->j_flags |= JFS_ABORT;
 	transaction = journal->j_running_transaction;
 	if (transaction)
-		__log_start_commit(journal, transaction->t_tid);
+		__log_start_commit(journal, transaction->t_tid, false);
 	spin_unlock(&journal->j_state_lock);
 }
 
diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c
index 5b2e4c3..a12c0a3 100644
--- a/fs/jbd/transaction.c
+++ b/fs/jbd/transaction.c
@@ -178,7 +178,7 @@ repeat_locked:
 		spin_unlock(&transaction->t_handle_lock);
 		prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
 				TASK_UNINTERRUPTIBLE);
-		__log_start_commit(journal, transaction->t_tid);
+		__log_start_commit(journal, transaction->t_tid, false);
 		spin_unlock(&journal->j_state_lock);
 		schedule();
 		finish_wait(&journal->j_wait_transaction_locked, &wait);
@@ -411,7 +411,7 @@ int journal_restart(handle_t *handle, int nblocks)
 	spin_unlock(&transaction->t_handle_lock);
 
 	jbd_debug(2, "restarting handle %p\n", handle);
-	__log_start_commit(journal, transaction->t_tid);
+	__log_start_commit(journal, transaction->t_tid, false);
 	spin_unlock(&journal->j_state_lock);
 
 	lock_map_release(&handle->h_lockdep_map);
@@ -1431,8 +1431,6 @@ int journal_stop(handle_t *handle)
 		}
 	}
 
-	if (handle->h_sync)
-		transaction->t_synchronous_commit = 1;
 	current->journal_info = NULL;
 	spin_lock(&journal->j_state_lock);
 	spin_lock(&transaction->t_handle_lock);
@@ -1463,7 +1461,8 @@ int journal_stop(handle_t *handle)
 		jbd_debug(2, "transaction too old, requesting commit for "
 					"handle %p\n", handle);
 		/* This is non-blocking */
-		__log_start_commit(journal, transaction->t_tid);
+		__log_start_commit(journal, transaction->t_tid,
+			handle->h_sync && !(current->flags & PF_MEMALLOC));
 		spin_unlock(&journal->j_state_lock);
 
 		/*
diff --git a/include/linux/jbd.h b/include/linux/jbd.h
index e069650..c38f73e 100644
--- a/include/linux/jbd.h
+++ b/include/linux/jbd.h
@@ -541,12 +541,6 @@ struct transaction_s
 	 * How many handles used this transaction? [t_handle_lock]
 	 */
 	int t_handle_count;
-
-	/*
-	 * This transaction is being forced and some process is
-	 * waiting for it to finish.
-	 */
-	unsigned int t_synchronous_commit:1;
 };
 
 /**
@@ -594,6 +588,8 @@ struct transaction_s
  *  transaction
  * @j_commit_request: Sequence number of the most recent transaction wanting
  *     commit
+ * @j_commit_waited: Sequence number of the most recent transaction someone
+ *     is waiting for to commit.
  * @j_uuid: Uuid of client object.
  * @j_task: Pointer to the current commit thread for this journal
  * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
@@ -762,6 +758,13 @@ struct journal_s
 	tid_t			j_commit_request;
 
 	/*
+	 * Sequence number of the most recent transaction someone is waiting
+	 * for to commit.
+	 * [j_state_lock]
+	 */
+	tid_t                   j_commit_waited;
+
+	/*
 	 * Journal uuid: identifies the object (filesystem, LVM volume etc)
 	 * backed by this journal.  This will eventually be replaced by an array
 	 * of uuids, allowing us to index multiple devices within a single
@@ -985,9 +988,9 @@ extern void	journal_switch_revoke_table(journal_t *journal);
  */
 
 int __log_space_left(journal_t *); /* Called with journal locked */
-int log_start_commit(journal_t *journal, tid_t tid);
-int __log_start_commit(journal_t *journal, tid_t tid);
-int journal_start_commit(journal_t *journal, tid_t *tid);
+int log_start_commit(journal_t *journal, tid_t tid, bool will_wait);
+int __log_start_commit(journal_t *journal, tid_t tid, bool will_wait);
+int journal_start_commit(journal_t *journal, tid_t *tid, bool will_wait);
 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);
-- 
1.7.1


--DocE+STaALJfprDB--
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