VFS - ENOTSUP vs ENOSYS

[Ira Cooper]

Hello,

I've hit a bug that I'm working on fixing involving kernel share modes,
and vfs modules that don't implement them.

But I realized, returning ENOSYS was wrong, because in this case
kernel_flock will implement it on XFS.  But Gluster doesn't support
kernel_flock.  So it should return ENOTSUP not ENOSYS, IMHO.  This
brings up a larger question... how many times are we returning ENOSYS
from the VFS where we mean ENOTSUP?

Just looking for thoughts on this one before I do a larger audit and
clean it up, in the VFS.  What do we want here?

Thanks,

-Ira