ext4: use sync_inode_metadata() when syncing inode metadata

We have a dedicated interface to sync inode metadata.  Use it to
simplify ext4's code some.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>

fs/ext4/fsync.c

@@ -44,7 +44,6 @@
  */
 static int ext4_sync_parent(struct inode *inode)
 {
-	struct writeback_control wbc;
 	struct dentry *dentry = NULL;
 	struct inode *next;
 	int ret = 0;
@@ -66,10 +65,7 @@ static int ext4_sync_parent(struct inode *inode)
 		ret = sync_mapping_buffers(inode->i_mapping);
 		if (ret)
 			break;
-		memset(&wbc, 0, sizeof(wbc));
-		wbc.sync_mode = WB_SYNC_ALL;
-		wbc.nr_to_write = 0;         /* only write out the inode */
-		ret = sync_inode(inode, &wbc);
+		ret = sync_inode_metadata(inode, 1);
 		if (ret)
 			break;
 	}