Re: [fuse-devel] Patches for FIEMAP support in fuse and ntfs-3g

[Miklos S. <mi...@sz...>]

On Sun, Feb 23, 2014 at 12:29 PM, Vitaliy Filippov <vi...@yo...> wrote:
> Hi!
>
> I've written some simple patches for FIEMAP support in fuse and ntfs-3g, via
> a separate FUSE opcode (not a generic ioctl). I wanted this feature to be
> able to play with in-place filesystem conversion, but discovered it wasn't
> there - even current fuse versions don't support it...
>
> The patches are attached, can you review them? There are patches for all
> parts: fuse kernel driver (for 3.12.x branch), fuse library and ntfs-3g
> implementation (including fuse-lite). All fiemap API constants are 'copied'
> into fuse. I've done some testing and it seems to work for both lowntfs-3g
> and ntfs-3g, both normal fuse and fuse-lite; 32-bit compat ioctl is also
> passed-through correctly.
>
> What do you think about this feature? :) and what's the process of getting
> it merged in general? This is especially interesting because this requires
> changes to different subsystems.

The implementation looks OK.

The issue I have with the interface is: why reinvent a new API on each
of the interfaces?  Yes, we do that for most requests, but here's a
request that is already in a flat structure format, exactly what the
kernel API needs.  So I suggest that we mirror the fiemap structures
there.  On the library API you can also just pass a "struct fiemap *"
pointer to the fiemap method and be done with that.

Thanks,
Miklos