Re: [PATCH] lockd: Fix comment about NLMv3 backwards compatibility

[NeilBrown]

On Fri, 13 Sep 2024, Pali Rohár wrote:
> NLMv2 is completely different protocol than NLMv1 and NLMv3, and in
> original Sun implementation is used for RPC loopback callbacks from statd
> to lockd services. Linux does not use nor does not implement NLMv2.
> 
> Hence, NLMv3 is not backward compatible with NLMv2. But NLMv3 is backward
> compatible with NLMv1. Fix comment.
> 
> Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
> ---
>  fs/lockd/clntxdr.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/lockd/clntxdr.c b/fs/lockd/clntxdr.c
> index a3e97278b997..81ffa521f945 100644
> --- a/fs/lockd/clntxdr.c
> +++ b/fs/lockd/clntxdr.c
> @@ -3,7 +3,9 @@
>   * linux/fs/lockd/clntxdr.c
>   *
>   * XDR functions to encode/decode NLM version 3 RPC arguments and results.
> - * NLM version 3 is backwards compatible with NLM versions 1 and 2.
> + * NLM version 3 is backwards compatible with NLM version 1.
> + * NLM version 2 is different protocol used only for RPC loopback callbacks
> + * from statd to lockd and is not implemented on Linux.
>   *
>   * NLM client-side only.
>   *

Reviewed-by: NeilBrown <neilb@xxxxxxx>

Do you have a reference for that info about v2?  I hadn't heard of it
before.

NeilBrown