f2fs: drop any block plugging

In f2fs, we don't need to keep block plugging for NODE and DATA writes, since
we already merged bios as much as possible.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 7b58bfb..eff046a 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -379,13 +379,8 @@
 			excess_prefree_segs(sbi) ||
 			excess_dirty_nats(sbi) ||
 			(is_idle(sbi) && f2fs_time_over(sbi, CP_TIME))) {
-		if (test_opt(sbi, DATA_FLUSH)) {
-			struct blk_plug plug;
-
-			blk_start_plug(&plug);
+		if (test_opt(sbi, DATA_FLUSH))
 			sync_dirty_inodes(sbi, FILE_INODE);
-			blk_finish_plug(&plug);
-		}
 		f2fs_sync_fs(sbi->sb, true);
 		stat_inc_bg_cp_count(sbi->stat_info);
 	}