Re: [PATCH v2 11/11] nfsd: wire up GET_DIR_DELEGATION handling

[Chuck Lever]

On 10/17/25 7:32 AM, Jeff Layton wrote:
> Add a new routine for acquiring a read delegation on a directory. These
> are recallable-only delegations with no support for CB_NOTIFY. That will
> be added in a later phase.
> 
> Since the same CB_RECALL/DELEGRETURN infrastrure is used for regular and
> directory delegations, a normal nfs4_delegation is used to represent a
> directory delegation.

s/infrastrure/infrastructure/


> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
>  fs/nfsd/nfs4proc.c  |  21 ++++++++++-
>  fs/nfsd/nfs4state.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfsd/state.h     |   5 +++
>  3 files changed, 125 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 7f7e6bb23a90d9a1cafd154c0f09e236df75b083..527f8dc52159803770964700170473509ec328ed 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -2342,6 +2342,13 @@ nfsd4_get_dir_delegation(struct svc_rqst *rqstp,
>  			 union nfsd4_op_u *u)
>  {
>  	struct nfsd4_get_dir_delegation *gdd = &u->get_dir_delegation;
> +	struct nfs4_delegation *dd;
> +	struct nfsd_file *nf;
> +	__be32 status;
> +
> +	status = nfsd_file_acquire_dir(rqstp, &cstate->current_fh, &nf);
> +	if (status != nfs_ok)
> +		return status;
>  
>  	/*
>  	 * RFC 8881, section 18.39.3 says:
> @@ -2355,7 +2362,19 @@ nfsd4_get_dir_delegation(struct svc_rqst *rqstp,
>  	 * return NFS4_OK with a non-fatal status of GDD4_UNAVAIL in this
>  	 * situation.
>  	 */
> -	gdd->gddrnf_status = GDD4_UNAVAIL;
> +	dd = nfsd_get_dir_deleg(cstate, gdd, nf);
> +	if (IS_ERR(dd)) {
> +		int err = PTR_ERR(dd);
> +
> +		if (err != -EAGAIN)
> +			return nfserrno(err);
> +		gdd->gddrnf_status = GDD4_UNAVAIL;
> +		return nfs_ok;
> +	}

These error flows might leak the nf acquired just above.


> +
> +	gdd->gddrnf_status = GDD4_OK;
> +	memcpy(&gdd->gddr_stateid, &dd->dl_stid.sc_stateid, sizeof(gdd->gddr_stateid));
> +	nfs4_put_stid(&dd->dl_stid);
>  	return nfs_ok;
>  }
>  
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index b06591f154aa372db710e071c69260f4639956d7..a63e8c885291fc377163f3255f26f5f693704437 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -9359,3 +9359,103 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
>  	nfs4_put_stid(&dp->dl_stid);
>  	return status;
>  }
> +
> +/**
> + * nfsd_get_dir_deleg - attempt to get a directory delegation
> + * @cstate: compound state
> + * @gdd: GET_DIR_DELEGATION arg/resp structure
> + * @nf: nfsd_file opened on the directory
> + *
> + * Given a GET_DIR_DELEGATION request @gdd, attempt to acquire a delegation
> + * on the directory to which @nf refers. Note that this does not set up any
> + * sort of async notifications for the delegation.
> + */
> +struct nfs4_delegation *
> +nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
> +		   struct nfsd4_get_dir_delegation *gdd,
> +		   struct nfsd_file *nf)
> +{
> +	struct nfs4_client *clp = cstate->clp;
> +	struct nfs4_delegation *dp;
> +	struct file_lease *fl;
> +	struct nfs4_file *fp, *rfp;
> +	int status = 0;
> +
> +	fp = nfsd4_alloc_file();
> +	if (!fp)
> +		return ERR_PTR(-ENOMEM);
> +
> +	nfsd4_file_init(&cstate->current_fh, fp);
> +
> +	rfp = nfsd4_file_hash_insert(fp, &cstate->current_fh);
> +	if (unlikely(!rfp)) {
> +		put_nfs4_file(fp);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	if (rfp != fp) {
> +		put_nfs4_file(fp);
> +		fp = rfp;
> +	}
> +
> +	/* if this client already has one, return that it's unavailable */
> +	spin_lock(&state_lock);
> +	spin_lock(&fp->fi_lock);
> +	/* existing delegation? */
> +	if (nfs4_delegation_exists(clp, fp)) {
> +		status = -EAGAIN;
> +	} else if (!fp->fi_deleg_file) {
> +		fp->fi_deleg_file = nf;
> +		fp->fi_delegees = 1;
> +	} else {
> +		++fp->fi_delegees;

The new nf is unused in this arm. Does it need to be released?


> +	}
> +	spin_unlock(&fp->fi_lock);
> +	spin_unlock(&state_lock);
> +
> +	if (status) {
> +		put_nfs4_file(fp);
> +		return ERR_PTR(status);
> +	}
> +
> +	/* Try to set up the lease */
> +	status = -ENOMEM;
> +	dp = alloc_init_deleg(clp, fp, NULL, NFS4_OPEN_DELEGATE_READ);
> +	if (!dp)
> +		goto out_delegees;
> +
> +	fl = nfs4_alloc_init_lease(dp);
> +	if (!fl)
> +		goto out_put_stid;
> +
> +	status = kernel_setlease(nf->nf_file,
> +				 fl->c.flc_type, &fl, NULL);
> +	if (fl)
> +		locks_free_lease(fl);
> +	if (status)
> +		goto out_put_stid;
> +
> +	/*
> +	 * Now, try to hash it. This can fail if we race another nfsd task
> +	 * trying to set a delegation on the same file. If that happens,
> +	 * then just say UNAVAIL.
> +	 */
> +	spin_lock(&state_lock);
> +	spin_lock(&clp->cl_lock);
> +	spin_lock(&fp->fi_lock);
> +	status = hash_delegation_locked(dp, fp);
> +	spin_unlock(&fp->fi_lock);
> +	spin_unlock(&clp->cl_lock);
> +	spin_unlock(&state_lock);
> +
> +	if (!status)
> +		return dp;
> +
> +	/* Something failed. Drop the lease and clean up the stid */
> +	kernel_setlease(fp->fi_deleg_file->nf_file, F_UNLCK, NULL, (void **)&dp);
> +out_put_stid:
> +	nfs4_put_stid(&dp->dl_stid);
> +out_delegees:
> +	put_deleg_file(fp);
> +	return ERR_PTR(status);
> +}
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index 1e736f4024263ffa9c93bcc9ec48f44566a8cc77..b052c1effdc5356487c610db9728df8ecfe851d4 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -867,4 +867,9 @@ static inline bool try_to_expire_client(struct nfs4_client *clp)
>  
>  extern __be32 nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp,
>  		struct dentry *dentry, struct nfs4_delegation **pdp);
> +
> +struct nfsd4_get_dir_delegation;
> +struct nfs4_delegation *nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
> +						struct nfsd4_get_dir_delegation *gdd,
> +						struct nfsd_file *nf);
>  #endif   /* NFSD4_STATE_H */
> 


-- 
Chuck Lever