Re: [PATCH v1 2/3] NFSD: Clear TIME_DELEG in the suppattr_exclcreat bitmap

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2025-11-14 at 15:29 -0500, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> From RFC 8881:
> 
> 5.8.1.14. Attribute 75: suppattr_exclcreat
> 
> > The bit vector that would set all REQUIRED and RECOMMENDED
> > attributes that are supported by the EXCLUSIVE4_1 method of file
> > creation via the OPEN operation. The scope of this attribute
> > applies to all objects with a matching fsid.
> 
> There's nothing in RFC 8881 that states that suppattr_exclcreat is
> or is not allowed to contain bits for attributes that are clear in
> the reported supported_attrs bitmask. But it doesn't make sense for
> an NFS server to indicate that it /doesn't/ implement an attribute,
> but then also indicate that clients /are/ allowed to set that
> attribute using OPEN(create) with EXCLUSIVE4_1.
> 
> The FATTR4_WORD2_TIME_DELEG attributes are also not to be allowed
> for OPEN(create) with EXCLUSIVE4_1. It doesn't make sense to set
> a delegated timestamp on a new file.
> 
> Fixes: 7e13f4f8d27d ("nfsd: handle delegated timestamps in SETATTR")
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  fs/nfsd/nfs4xdr.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 51ef97c25456..8f12dee4c3b5 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3379,6 +3379,8 @@ static __be32 nfsd4_encode_fattr4_suppattr_exclcreat(struct xdr_stream *xdr,
>  		supp[0] &= ~FATTR4_WORD0_ACL;
>  	if (!args->contextsupport)
>  		supp[2] &= ~FATTR4_WORD2_SECURITY_LABEL;
> +	supp[2] &= ~FATTR4_WORD2_TIME_DELEG_ACCESS;
> +	supp[2] &= ~FATTR4_WORD2_TIME_DELEG_MODIFY;
>  

Why not just clear those bits in NFSD_SUPPATTR_EXCLCREAT_WORD2 ?

>  	supp[0] &= NFSD_SUPPATTR_EXCLCREAT_WORD0;
>  	supp[1] &= NFSD_SUPPATTR_EXCLCREAT_WORD1;


-- 
Jeff Layton <jlayton@kernel.org>