xfs: add missing cmap->br_state = XFS_EXT_NORM update

COW extents are already converted into written real extents after
xfs_reflink_convert_cow_locked(), therefore cmap->br_state should
reflect it.

Otherwise, there is another necessary unwritten convertion
triggered in xfs_dio_write_end_io() for direct I/O cases.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/xfs/xfs_reflink.c

@@ -425,7 +425,10 @@ xfs_reflink_allocate_cow(
 	if (!convert_now || cmap->br_state == XFS_EXT_NORM)
 		return 0;
 	trace_xfs_reflink_convert_cow(ip, cmap);
-	return xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
+	error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
+	if (!error)
+		cmap->br_state = XFS_EXT_NORM;
+	return error;
 
 out_trans_cancel:
 	xfs_trans_cancel(tp);