[PATCH 5/6] jbd2: use WRITE_SYNC for journal I/O

[Jeff Moyer <jmoyer@redhat.com>]

In my fsync testing, journal I/O most definitely was sync I/O, since
another process was blocked waiting for the results.  By marking all
journal I/O as WRITE_SYNC, I can get better performance with CFQ.

If there is a way to mark this only for cases where it is blocking progress
in a dependent process, then that would be preferrable.  Is there such a
means for determining and flagging this?

Cheers,
Jeff

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
---
 fs/jbd2/commit.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 75716d3..a078744 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -369,7 +369,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	int tag_bytes = journal_tag_bytes(journal);
 	struct buffer_head *cbh = NULL; /* For transactional checksums */
 	__u32 crc32_sum = ~0;
-	int write_op = WRITE;
+	int write_op = WRITE_SYNC;
 
 	/*
 	 * First job: lock down the current transaction and wait for
-- 
1.6.5.2