Re: [PATCH v2] NFSD: Rework encoding and decoding of nfsd4_deviceid

[Chuck Lever]

On 7/22/25 1:36 AM, Christoph Hellwig wrote:
> On Mon, Jul 21, 2025 at 05:48:55PM +0300, Sergey Bashirov wrote:
>> Compilers may optimize the layout of C structures,
> 
> By interpreting the standard in the most hostile way: yes.
> In practice: no.

Earnest question: Is NFSD/XDR properly insulated against the "randomize
structure layout" option?


> Just about every file system on-disk format and every network wire
> protocol depends on the compiler not "optimizing" properly padded
> C structures.
It's an intrinsic assumption that is not documented in the code or
anywhere else. IMO that is a latent banana peel.

While not urgent, this is a defensive change and it improves code
portability amongst compilers and languages (eg, Rust).


-- 
Chuck Lever