MNTK_DRAINING
mp->mnt_kern_flag |= MNTK_DRAINING;
MNT_KERN_FLAG(MNTK_DRAINING);
MPASS((mp->mnt_kern_flag & MNTK_DRAINING) == 0);
MPASS((mp->mnt_kern_flag & MNTK_DRAINING) == 0);
MPASS((mp->mnt_kern_flag & MNTK_DRAINING) == 0);
if (c == 0 && (mp->mnt_kern_flag & MNTK_DRAINING) != 0) {
mp->mnt_kern_flag &= ~MNTK_DRAINING;