vfs_checkexp
if (vfsops->vfs_checkexp == NULL) {
vfsops->vfs_checkexp = vfs_stdcheckexp;
error = (mp->mnt_op->vfs_checkexp)(mp, nam, extflagsp, credanonp);
int vfs_checkexp(struct mount *mp, struct sockaddr *nam,
vfs_checkexp_t *vfs_checkexp;
vfs_checkexp(MP, NAM, EXFLG, CRED)
.vfs_checkexp = dirfs_checkexp
.vfs_checkexp = ext2_check_export,
.vfs_checkexp = hammer_vfs_checkexp
.vfs_checkexp = hammer2_vfs_checkexp,
.vfs_checkexp = hpfs_checkexp,
.vfs_checkexp = cd9660_checkexp,
.vfs_checkexp = ufs_check_export,
.vfs_checkexp = msdosfs_checkexp,
.vfs_checkexp = ntfs_checkexp,
.vfs_checkexp = nullfs_checkexp,
.vfs_checkexp = tmpfs_checkexp,
.vfs_checkexp = ufs_check_export,