Re: [PATCH v6 18/20] nfsd: properly track requested child attributes

["Chuck Lever" <cel@kernel.org>]

On Thu, Jun 11, 2026, at 1:50 PM, Jeff Layton wrote:
> Track the union of requested and supported child attributes in the
> delegation, and only encode the attributes in that union when sending
> add/remove/rename updates.
>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/nfsd/nfs4proc.c  |  2 ++
>  fs/nfsd/nfs4state.c | 18 ++++++++++++++++++
>  fs/nfsd/nfs4xdr.c   | 15 ++++++---------
>  fs/nfsd/state.h     |  3 +++
>  4 files changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 29f7339dc220..caec82e77081 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -2577,6 +2577,8 @@ nfsd4_get_dir_delegation(struct svc_rqst *rqstp,
> 
>  	gdd->gddrnf_status = GDD4_OK;
>  	memcpy(&gdd->gddr_stateid, &dd->dl_stid.sc_stateid, 
> sizeof(gdd->gddr_stateid));
> +	gdd->gddr_child_attributes[0] = dd->dl_child_attrs[0];
> +	gdd->gddr_child_attributes[1] = dd->dl_child_attrs[1];
>  	nfs4_put_stid(&dd->dl_stid);
>  	return nfs_ok;
>  }
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index aa99783ce901..0e6e008c121e 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -9930,6 +9930,21 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst 
> *rqstp, struct dentry *dentry,
>  	return status;
>  }
> 
> +#define GDD_WORD0_CHILD_ATTRS	(FATTR4_WORD0_TYPE |		\
> +				 FATTR4_WORD0_CHANGE |		\
> +				 FATTR4_WORD0_SIZE |		\
> +				 FATTR4_WORD0_FILEID |		\
> +				 FATTR4_WORD0_FILEHANDLE)
> +
> +#define GDD_WORD1_CHILD_ATTRS	(FATTR4_WORD1_MODE |		\
> +				 FATTR4_WORD1_NUMLINKS |	\
> +				 FATTR4_WORD1_RAWDEV |		\
> +				 FATTR4_WORD1_SPACE_USED |	\
> +				 FATTR4_WORD1_TIME_ACCESS |	\
> +				 FATTR4_WORD1_TIME_METADATA |	\
> +				 FATTR4_WORD1_TIME_MODIFY |	\
> +				 FATTR4_WORD1_TIME_CREATE)
> +
>  /**
>   * nfsd_get_dir_deleg - attempt to get a directory delegation
>   * @cstate: compound state
> @@ -9998,6 +10013,9 @@ nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
>  		dp->dl_stid.sc_export =
>  			exp_get(cstate->current_fh.fh_export);
> 
> +	dp->dl_child_attrs[0] = gdd->gdda_child_attributes[0] & 
> GDD_WORD0_CHILD_ATTRS;
> +	dp->dl_child_attrs[1] = gdd->gdda_child_attributes[1] & 
> GDD_WORD1_CHILD_ATTRS;
> +
>  	/*
>  	 * NB: gddr_notification[0] represents the notifications that
>  	 * will be granted to the client
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 15ccd54ffdb6..1e3c360c06cd 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -4271,18 +4271,15 @@ nfsd4_setup_notify_entry4(struct notify_entry4 
> *ne, struct xdr_stream *xdr,
> 
>  	args.change_attr = nfsd4_change_attribute(&args.stat);
> 
> -	attrmask[0] = FATTR4_WORD0_TYPE | FATTR4_WORD0_CHANGE |
> -		      FATTR4_WORD0_SIZE | FATTR4_WORD0_FILEID;
> -	attrmask[1] = FATTR4_WORD1_MODE | FATTR4_WORD1_NUMLINKS | 
> FATTR4_WORD1_RAWDEV |
> -		      FATTR4_WORD1_SPACE_USED | FATTR4_WORD1_TIME_ACCESS |
> -		      FATTR4_WORD1_TIME_METADATA | FATTR4_WORD1_TIME_MODIFY;
> +	attrmask[0] = dp->dl_child_attrs[0];
> +	attrmask[1] = dp->dl_child_attrs[1];
>  	attrmask[2] = 0;
> 
> -	if (setup_notify_fhandle(dentry, fi, nf, &args))
> -		attrmask[0] |= FATTR4_WORD0_FILEHANDLE;
> +	if (!setup_notify_fhandle(dentry, fi, nf, &args))
> +		attrmask[0] &= ~FATTR4_WORD0_FILEHANDLE;
> 
> -	if (args.stat.result_mask & STATX_BTIME)
> -		attrmask[1] |= FATTR4_WORD1_TIME_CREATE;
> +	if (!(args.stat.result_mask & STATX_BTIME))
> +		attrmask[1] &= ~FATTR4_WORD1_TIME_CREATE;
> 
>  	ne->ne_attrs.attrmask.count = 2;
>  	ne->ne_attrs.attr_vals.data = (u8 *)xdr->p;
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index d912e3d04dd7..0763893bfd48 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -297,6 +297,9 @@ struct nfs4_delegation {
>  	struct timespec64	dl_atime;
>  	struct timespec64	dl_mtime;
>  	struct timespec64	dl_ctime;
> +
> +	/* For dir delegations */
> +	uint32_t		dl_child_attrs[2];
>  };
> 
>  static inline bool deleg_is_read(u32 dl_type)
>

When a client requests any supported child attribute in word 1, this can
make gddr_child_attributes[1] non-zero, so nfsd4_encode_bitmap4() emits a
two-word bitmap. nfsd4_get_dir_delegation_rsize() still budgets only the
old one-word child-attribute bitmap before executing this non-idempotent
op, so a compound near the reply/slot limit can grant a directory
delegation and then fail encoding with NFS4ERR_RESOURCE/REP_TOO_BIG,
leaving the client without the returned stateid.


-- 
Chuck Lever