The statfs man page is out of date with the current statfs structure, in
particular, f_fsize & f_bsize became f_bsize & f_iosize.

Also, <sys/param.h> is required to be included by user code to use struct
statfs, because NGROUPS is needed via <sys/ucred.h> to define another
struct in <sys/mount.h>.

Perhaps param.h should be included with ucred.h in mount.h, or else the
need for it documented in stat(2).

FYI,
Jaime

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