> > >
> > > Why doesn't this function just call fiemap_fill_kernel_extent to fill
> > > out the onstack @extent structure? We've now implemented "fill out out
> > > a struct fiemap_extent" twice.
> >
> > fiemap_fill_{user, kernel}_extent() have different purposes, and the big
> > difference is one handles a userspace pointer memory and the other don't. IIRC
> > the original proposal was some sort of sharing a single function, but then
> > Christoph suggested a new design, using different functions as callbacks.
>
> It's harder for me to tell when I don't have a branch containing the
> final product to look at,
Good, I though I was the only one having issues with it :)
You can see the work here:
https://github.com/cmaiolino/linux/commits/FIEMAP_V5
^ This already includes changes addressing your concerns as we discussed int
this thread btw.
> but I'd have thought that _fill_kernel fills
> out an in-kernel fiemap extent; and then _fill_user would declare one on
> the stack, call _fill_kernel to set the fields, and then copy_to_user?
None of those functions will declare a fiemap_extent, the fiemap extent will be
declared before (in ioctl_fiemap() or bmap_fiemap()) calling either function and
then passed to the proper callback via fieinfo.fi_cb_data. This will be a user
or a kernel memory address, and the callbacks will handle the memory accordingly.
Cheers
--
Carlos
