kernfs_mount
#define VFSTOKERNFS(mp) ((struct kernfs_mount *)((mp)->mnt_data))
struct kernfs_mount *fmp;
fmp = kmem_zalloc(sizeof(struct kernfs_mount), KM_SLEEP);
kmem_free(fmp, sizeof(struct kernfs_mount));
kmem_free(mp->mnt_data, sizeof(struct kernfs_mount));
.vfs_mount = kernfs_mount,