The issue has to do with how flags are defined in mount.h.
Specifically there are the flags that are externally visible
(prefixed with MNT_) and those that are for internal use
(prefixed with MNTK_, the K standing for KERNEL). If it
is desirable to have MNTK_NULL_NOCACHE visible, then it
should be renamed to MNT_NULL_CACHE, added to MNT_VISFLAGMASK,
and listed in MNTOPT_NAMES. It probably belongs in the set
described as `Flags set by internal operations, but visible
to the user.' With this change, it will be displayed by
the mount command and show up in the statfs flags.
Kirk McKusick
