On Wed, Oct 24, 2018 at 12:47:57PM +1100, NeilBrown wrote: > > I doubt it was copied - more likely independent evolution. > But on reflection, I see that it is probably reasonable that it > shouldn't be used this way - or at all in this context. > I'll try to understand what the issues really are and see if I can > find a solution that doesn't depend on this interface. > Thanks for your help.
At least for ext4, the primary problem is that we want to use a 64-bit telldir/seekdir cookie if all 64-bits will make it to user space, and a 32-bit telldir cookie if only 32 bits will make it userspace. This impacts NFS as well because if there are people who are still using NFSv2, which has 32-bit directory offsets, we need to constrain the telldir/seekdir cookies we give to NFS to be a 32 has as opposed to a 64-bit hash. - Ted