[OpenAFS-devel] afs_syscall_pioctl

[Nickolai Zeldovich]

> I'm looking at afs_syscall_pioctl and I can't figure out how it could
> possibly work, except by accident.  I think all calls to afs_HandlePioctl
> require a VTOAFS() on the first arg.  That's what the old Transarc code did.

It looks like you're absolutely correct -- we should call VTOAFS() on
the first arg of afs_HandlePioctl.  However, it's pretty simple to see
why it worked all this time:

  #define VTOAFS(V) ((struct vcache *)(V))

which is #ifndef AFS_OBSD_ENV.  I looked back over various versions of
Transarc AFS from 3.1b to 3.6p1, and didn't find any version that called
VTOAFS() or equivalent in afs_syscall_pioctl.  They did have a special
case for Ultrix, as far back as 3.1b, where they called afs_gntovn()
beforehand.  But the VTOAFS() macro was only added in OpenAFS (in delta
convert-vcache-casts-to-macros-20020325), which explains why it's not
used everywhere it should be.

-- kolya