Re: [PATCH v6 16/20] nfsd: add a fi_connectable flag to struct nfs4_file

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

On Thu, Jun 11, 2026, at 1:50 PM, Jeff Layton wrote:
> When encoding a filehandle for a CB_NOTIFY, there is no svc_export
> available, but the server needs to know whether to encode a connectable
> filehandle. Add a flag to the nfs4_file that tells whether the
> svc_export under which a directory delegation was acquired has subtree
> checking enabled, in which case it needs connectable filehandles.
>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/nfsd/nfs4state.c | 1 +
>  fs/nfsd/state.h     | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 513cbc1a583f..aa99783ce901 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -5231,6 +5231,7 @@ static void nfsd4_file_init(const struct svc_fh 
> *fh, struct nfs4_file *fp)
>  	memset(fp->fi_access, 0, sizeof(fp->fi_access));
>  	fp->fi_aliased = false;
>  	fp->fi_inode = d_inode(fh->fh_dentry);
> +	fp->fi_connectable = !(fh->fh_export->ex_flags & 
> NFSEXP_NOSUBTREECHECK);
>  #ifdef CONFIG_NFSD_PNFS
>  	INIT_LIST_HEAD(&fp->fi_lo_states);
>  	atomic_set(&fp->fi_lo_recalls, 0);
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index f8457e0f2b57..d912e3d04dd7 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -761,6 +761,7 @@ struct nfs4_file {
>  	int			fi_delegees;
>  	struct knfsd_fh		fi_fhandle;
>  	bool			fi_had_conflict;
> +	bool			fi_connectable;
>  #ifdef CONFIG_NFSD_PNFS
>  	struct list_head	fi_lo_states;
>  	atomic_t		fi_lo_recalls;
>

When two clients use exports of the same directory root that
differ only in subtree_check/no_subtree_check, the root filehandle
is the same and nfsd4_file_hash_insert() can reuse the same
nfs4_file. This makes fi_connectable depend on whichever export
first initialized the shared object, so a later directory
delegation acquired under the other export can encode CB_NOTIFY
child filehandles with the wrong connectability.

Therefore, the delegation's sc_export is the per-export state to
derive connectability from, and the export is already available
via dp->dl_stid.sc_export.


-- 
Chuck Lever