exofs: Avoid using file_fsync()

The use of file_fsync() in exofs_file_sync() is not necessary since it
does some extra stuff not used by exofs. Open code just the parts that
are currently needed.

TODO: Farther optimization can be done to sync the sb only on inode
update of new files, Usually the sb update is not needed in exofs.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
diff --git a/fs/exofs/super.c b/fs/exofs/super.c
index e47b38e..a343b4e 100644
--- a/fs/exofs/super.c
+++ b/fs/exofs/super.c
@@ -198,7 +198,7 @@
 /*
  * Write the superblock to the OSD
  */
-static int exofs_sync_fs(struct super_block *sb, int wait)
+int exofs_sync_fs(struct super_block *sb, int wait)
 {
 	struct exofs_sb_info *sbi;
 	struct exofs_fscb *fscb;