xfs_getfsmap_dev
struct xfs_getfsmap_dev handlers[XFS_GETFSMAP_DEVS];
xfs_sort(handlers, XFS_GETFSMAP_DEVS, sizeof(struct xfs_getfsmap_dev),
const struct xfs_getfsmap_dev *d1 = p1;
const struct xfs_getfsmap_dev *d2 = p2;