UBIFS: remove manual O_SYNC handling

generic_file_aio_write already calls into ->fsync to handle O_SYNC/O_DSYNC.
Remove the duplicate call to ubifs_sync_wbufs_by_inode which is already
covered by ubifs_fsync.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

fs/ubifs/file.c

@@ -1389,7 +1389,6 @@ static ssize_t ubifs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 			       unsigned long nr_segs, loff_t pos)
 {
 	int err;
-	ssize_t ret;
 	struct inode *inode = iocb->ki_filp->f_mapping->host;
 	struct ubifs_info *c = inode->i_sb->s_fs_info;
 
@@ -1397,17 +1396,7 @@ static ssize_t ubifs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	if (err)
 		return err;
 
-	ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
-	if (ret < 0)
-		return ret;
-
-	if (ret > 0 && (IS_SYNC(inode) || iocb->ki_filp->f_flags & O_SYNC)) {
-		err = ubifs_sync_wbufs_by_inode(c, inode);
-		if (err)
-			return err;
-	}
-
-	return ret;
+	return generic_file_aio_write(iocb, iov, nr_segs, pos);
 }
 
 static int ubifs_set_page_dirty(struct page *page)