This patch fixes performance regression of dbench reported by
Alex <hbx7d@yandex.com>.
This issue was revealed by Phoronix tests results:
http://www.phoronix.com/scan.php?page=article&item=linux_314_ssdfs&num=2
It turns out that we need to assign WRITE_SYNC to the node writes, if
fsync is triggered.
The performance numbers are like below, which is measured by Alex.
1. 355MB/s ext4
2. 225MB/s f2fs : WRITE for node writes
3. 525MB/s f2fs : WRITE_SYNC for node writes
Reported-And-Tested-by: Alex <hbx7d@yandex.com>.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
c81bf1c84f