Re: [PATCH v2 5/5] staging: lustre: headers: use proper byteorder functions in lustre_idl.h

From: Dilger, Andreas
Date: Mon Dec 12 2016 - 19:55:08 EST

On Dec 12, 2016, at 13:00, James Simmons <jsimmons@xxxxxxxxxxxxx> wrote:
>> On Sat, Dec 10, 2016 at 01:06:01PM -0500, James Simmons wrote:
>>> In order for lustre_idl.h to be usable for both user
>>> land and kernel space it has to use the proper
>>> byteorder functions.
>> Why would userspace need/want all of these inline functions? A uapi
>> header file should just have a the structures that are passed
>> user/kernel and any needed ioctls. Why would they ever care about
>> strange byte flip functions and a ton of inline functions?
>> I don't think this is needed, of if it is, I really don't want to see
>> your crazy userspace code...
> Sigh. More cleanups were done based on the idea this was okay. The
> reason this was does was when you look at the headers in
> include/uapi/linux you see a huge number of headers containing a bunch
> of inline function. To an outside project looking to merge their work
> into the kernel they would think this is okay. Hopefully all those
> broken headers will be cleaned up in the near future.
> Alright I will look to fixing up our tools to handle this requirement.

These accessor functions are used by both the kernel and userspace
tools, and keeping them in the lustre_idl.h header avoids duplication
of code. Similar usage exists in other filesystem related uapi headers
(e.g. auto_fs4.h, bcache.h, btrfs_tree.h, nilfs2_ondisk.h, swab.h, etc.).

That said, if there is an objection to keeping these macros/inline funcs
in the uapi headers, they still need to exist in the kernel and should
be kept in the lustre/include/lustre directory and we'll keep a separate
copy of the macros for userspace.

Cheers, Andreas