STABLE14-STABLE12-implement-vpeek-for-listvol-20041211

STABLE14-STABLE12-implement-vpeek-for-listvol-20041211

FIXES 16765

 All of AFSVolListOneVolume, AFSVolXListOneVolume, AFSVolListVolumes,
 AFSVolXListVolumes currrently attach each volume to be listed with
 V_READONLY.  This makes the fileserver update and sync the volume header
 before releasing the volume to the volserver.  The result is that volume
 list operations are slow, and generate lots of fileserver load, as Jimmy
 pointed out during his talk this afternoon.

 The attached patch introduces a new attach mode, V_PEEK, which is like a
 cross between V_READONLY and V_SECRETLY.  It can be used for read-only
 operations on the volume header, where it is not necessary to inform the
 fileserver that the volume is being accessed.  The patch also changes
 the above-named RPC's to use the new mode.