Description of problem: This can be implemented using 'xfs_admin -L newlabel /dev/sdX' (Requested by: Bo Fan).
Fixed/implemented upstream: https://github.com/libguestfs/libguestfs/commit/091d22f49e7fcb53fb3bb23e2ba94ca12eb88eab https://github.com/libguestfs/libguestfs/commit/8580ef7d0f2aac2118fa7b4055f3eb28cd127093 https://github.com/libguestfs/libguestfs/commit/df02c2471f3fe94c691c389c17a5d23d052848dd https://github.com/libguestfs/libguestfs/commit/8965368eb89532ac1613fffb0a3a661f005bae81